Good morning students. Today I will be talking to you about new macro a molecule which plays
a very significant and important role in most of the cellular activities of the cell.
And that macro molecule is called protein. Now, the protein the term protein is derived
from the Greek word, which is proteios means it holding it is holding the first place.
Protein occurs in every part of the cell and it constitutes 50 percent of the cellular
dry weight. Now, proteins are the most abundant organic molecule of the living system. Now,
if we see the different protein molecules the most commonly found proteins in the animal
system is the collagen. Collagen is the most abundant protein in the animal world whereas,
RUBISCO Ribulose bisphosphate Carboxylase-Oxygenase this is one of the protein molecule enzyme
protein which is available plenty in the plant system.
So, if we see the function of a protein molecule we can broadly group the function of this
protein into two basic structure divisions. One is the static or the structural function
another is the dynamic function. Now, as far as the structural function is concerned the
name itself indicates that it gives the structural and the strength of the body. Collagen Elastin
etcetera are the protein molecules which are found in bone matrix and alpha keratin in
the epidermal tissues of the cell.
Whereas, the dynamic function it is the protein that diversified which are diversified in
nature and they play different catalytic role like enzymes. Enzymes are the biocatalyst
and they play different catalytic role in the cell. Similar to that hormones, immunoglobulins,
blood clotting factors, membrane receptor storage lipid etcetera, are coming under these
categories.
Now, in my earlier lecture I have told you that there are certain molecules which constitute
This macro molecular structure and if we see that carbon, hydrogen, oxygen, nitrogen and
sulfur are the basic constituent of this protein molecule. If we see the percentage of carbon
it varies from 50 to 55 percent whereas, nitrogen 6 to 7 percent, oxygen 19 to 24 percent, nitrogen
13 to 19 percent and sulfur 0 to 4 percent. That means if, we see the major constituent
we can find that that carbon, hydrogen, oxygen, nitrogen and sulfur are the basic constituent
of the protein molecule.
Besides these above molecules protein contains some elements such as phosphorous, ferrous,
copper, iodine, magnesium, manganese, zinc etcetera. With within it the content of this
nitrogen and essential component of the protein varies on an average to 16 percent.
Now, this is the basic constituent of the molecules which constitute the protein.
Now, when we are talking about these amino acids, amino acids are the basic building
block of protein molecule. Now, proteins are the macro molecules which are polymers in
nature polymeric in nature. And the basic constituent of this polymers are the alpha
amino acid there are more than 300 amino acids, which are there in this nature.
But, only 20 amino acids are considered to be the standard amino acid and with it is
permutation and combinations protein structure is made amino acid consist of two fundamental
groups. That means if we see the structure of amino acid we can find that this amino
acid.
Has got one carboxyl end amino acid has got one amino end and one amino acid is different
from the another amino acid with it is R group. So, this is the side chain and this side chain
varies from one amino acid to the another amino acid. So, this is the fundamental basic
structure of any amino acid and as this is the first carbon then this functional carbon
this is the alpha carbon and this is this is the basic structure of amino acid. So,
if we see the structure one hydrogen is present one carboxyl end is there carboxylic acid
and C O O H group is there, one amino group is there and the side chain R group is present
in the basic core structure of amino acid.
Now, if we divide this 20 standard amino acid based on it is characteristics or based on
the properties of this R group. It can be categorized into 4 different divisions. One
is called the non polar or the hydrophobic amino acid, second group is the polar or hydrophilic
amino acid, third is the acidic amino acid and fourth group is the basic amino acid.
Now, whatever is there the 20 standard amino acids has been divided into these 4 different
categories. So, this 20 standard amino acid has been divided into 4 different categories
some are non polar, some are polar, some are acidic and some are basic in nature. Now,
let us come to the non polar amino acid. Alanine, proline, valine, phenylalanine, tyrosine,
tryptophan, methionine, isoleucine and leucine are the non polar or the hydrophobic amino
acid. What is the basic nature of this type of amino acid they are insoluble mostly or
sparingly soluble in water. Now, these are the R group so, when I am talking to you this
is the R group and this is the core moieties of the amino acid, these core moieties are
same in most of the amino acids. .
Now, when we are coming to the polar R group then we can find that serine threonine, cysteine,
glycine, asparagines, glutamine are the polar amino acid, where glycine is the amino acid
which is placed on the transition phase of polar and non polar amino acid. Now, this
is the only amino acid where this carbon is not an asymmetric carbon atom that means here
this R group is also another hydrogen H. So, as this is H this glycine is not having this
chiral carbon within it when we are coming to the basic amino acid. It is otherwise known
as positively charged amino acid and here. We can find that in case of lysine here that
additional amino containing groups are there arginine has got guanidini group and histidine
has got imidazolium group within it. And here they have this additional amino containing
group within it and that is the reason why it is called the basic amino acid, whereas
the negatively charged amino acids are the aspartic acid and the glutamic acid.
Now, here I would like to tell you that amino acid if, we see the core structure of this
amino acid as I have already discussed.
That it has got the carboxyl end and another is that amino end. So, besides this carboxylic
group and the within the core structure of this particular amino acid and additional
C O O H group is present in both these amino acid. That aspartic acid and glutamic acid
resulting the nature of this amino acid acidic in nature. So, these are the broad classification
of this amino acid amino acid can also be classified based on this aromatic ring some
groups can be also once again taken which contain the aromatic amino acid such as this
phenylalanine tyrosine tryptophan and so on so based on the it is structure the twenty
standard amino acid has been classified.
Now this amino acids are playing a very important role as far as the mechanism the cell functionality
is concerned and that is the reason this amino acids has been classified or symbolized with
either three letter digit or with one letter digit say for example, now glycine if we considered
glycine as one of the amino acid it can be denoted by G l y that is the three letter
symbol and in single letter it is G alanine is A or A l a and A valine is V a l or V leucine
is L e u or L. So, in this way these 20 standard amino acids
are classified with the 3 letter and single letter symbol. The significant of this single
letter and 3 digit symbol you will be understanding gradually when we will be going little bit
in depth of and you will be learning the role of other macro molecular structure and functionality
of that particular macro molecule in the cell system. So, these are the 3 letters and single
letter symbol of amino acid.
Now, as I have told you this is the basic ionic form of amino acid this is the carboxyl
end and this is the amino end and this R group. So, as I have already told you that R group
of each standard 20 standard amino acid varies from each other and which makes one amino
acid different from another amino acid
Now, if we go for this classification of amino acid, then amino acids are classified based
on the structure and the chemical nature. That is the nutritional requirement and the
metabolic activities of any living cell. Now, based on the nutritional requirement
then this amino acids has been classified into two types. One is called the essential
amino acid another is the non essential amino acid. Now, what is essential amino acid this
essential amino acids.
Which cannot be synthesized by our body system? That means for the supplementation of these
amino acids, we have to supplement these amino acids through diet and what are those amino
acids, which are which cannot be synthesized by the body. They are arginine, Valine, Histidine,
Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, threonine and tryptophan. So, these are the
amino acids which cannot be synthesized within the body system. And that is the reason it
these amino acids are replaced or it is the demand is meet through diet or food. Arginine
and histidines are the amino acids which are synthesized by the adult. But, it cannot be
it is not present in the growing children.
In case of non essential amino acid that means those amino acids which can be synthesized
by the body system itself. That means glycine, alanine, serine, cysteine, aspartic acid,
asparagine glutamic acid, glutamine, tyrosine and proline these are the amino acid body
can synthesize these amino acid by itself. So, supplementations of these amino acids
are not that essential.
Now, when we are coming to the properties of this amino acid, now amino acid can be
denoted by a proton or it can donate proton or accept proton due to the presence of the
C O O H group. And amino group present within it Zwitterionic form it is a hybrid molecule
containing a positively charged as well as a negatively charged ionic group within it.
That means if we see this structure it has got positive charge as well as negative charge
resulting charge in the Zwitterionic condition is 0.That means no net charge is present on
the surface of the amino acid. Isoelectric point it is isoelectric p H is
that p H where a molecule exist as a Zwitterionic condition that means no net charge is there.
So, positive charge is equal to the negative charge that means when we are passing this
protein molecule or this amino acid in a electrical field. There will be no movement because of
the net charge as it is 0 or neutral.
Now, this amino acid can be seen by the Fischer projection all amino acids except glycine.
I have already mentioned that in glycine the R group is simply H and that is the reason.
It is not the chiral molecule amino acids have stereoisomer and in biological system
only L form of amino acids are used in the protein molecule and not the D form this is
the L form and this is the D form. So, this L form of amino acid is present in
the protein molecule but, in D form this is found in the larvae and pupae of the insect.
So, these are not playing any role as far as the protein is concerned now.
When we are talking about the D and L form of amino acid, we can find that every amino
acid has a similar basic structure that means one amino terminal another carboxy terminals
are there except for glycine. Where R is H all amino acids have at least one asymmetric
carbon atom and exist as two stereoisomer. That is either the D form or the L form this
is the D form or the L form. So, why this is the chiral carbon and it is the amino group
is present here and in the D form the amino group is present on the right hand side.
So, this is the D form and L form of these amino acid. So, stereoisomeric character is
one of the very important properties which determine the L form or D form of this amino
acid.
Now, amino acid when it is acting as acid in solution more basic than the p I. That
p I what is the p I it is the isoelectric point where there is no net charge, which
is present on this amino acid the amino NH 3 plus in the amino acid donate a proton to
this and it forms. This ionic structure so, this is the Zwitterionic at the neutral p
H, p I and here under the basic condition where hydroxyl group are there. So, in higher
P H this P I is having this it can donate a proton to these and making this structure
N H 2 C H 2 and C O O minus.
Similarly when the solution is more acidic than the p I the C O O minus that carboxyl
group in the amino acid accept a proton. And this is the structure of this and it becomes
N H 3 C H 2 and C O O H and this is the characteristics or the behavioral properties of amino acid.
Now, coming to the little complex structure of this amino acid, I have already mention
you that this amino acids are the basic building block of protein molecule.
That means this amino acid constitutes the protein molecule. So, how it is that means
it is joining together and when one amino acid is joining with another amino acid. The
joining it forms the amide bond now, what is that now if we see.
The structure of one amino acid now see this is the structure of one amino acid this is
the R 1 this is C H this is the amino terminal and this is the carboxy terminal.
Now, when one amino acid is joining with the another amino acid that means I have already
mention you that amino acid has got two terminal one is the amino end another is the carboxyl
end. So, one carboxyl end of one amino acid when it joins with the amino terminal of the
second amino acid they form the amide bond. Now, when C O O H is coming in contact with
this N H 2 they form they release a molecule of water from these and this bond is called
the amide bond. Now, in this way when it forms a chain like structure it is the called the
peptide bonding. So, peptide bond is the amide bond.
Between the carboxyl group of one amino acid this is the first amino acid, this is the
Second amino acid, this is the third amino acid and this is the fourth amino acid, so
this when this amino acids are joining together and making a chain like structure.
Then it is called the peptide bonding.
Now, classification and they form. The protein structure now, when we are coming to this
protein. Now, let us come to this classification of protein. Now, based on the amino acid composition
structure shape and solubility properties of the protein are broadly classified into
3 major groups. First group is called the simple protein they are composed of only the
amino acid residues. It consists of the globular and the fibrous protein example is albumin,
globulin, histone, collagen etcetera.
Now, when we are coming to this globular protein it is usually water soluble compact and roughly
spherical in nature hydrophobic interior and hydrophilic surface. Now, globular protein
includes the enzyme carrier and the regulatory protein. That means if we see the nature of
this amino acid I told based on the characteristics of this amino acids. That means hydrophilic
amino acids are present on the surface of the protein whereas, hydrophobic moieties
because hydrophobic are water heating. Water is not a very suitable environment for
them they try to put it inside where is which is covered by the hydrophilic moieties.
So, these type of protein this combinations it forms the protein structure and it is forming
the globular protein.
When we are coming to this fibrous protein it provides the mechanical support of an assembled
in a large cable or thread like structure alpha keratin, which is a major component
of hairs nails etcetera are the example of alpha keratin, which are insoluble in water.
Collagens are the major component of the tendon skin, bones, teeth etcetera. Where these collagen
proteins are there so you can understand that all this biomolecules, which we are carrying,
are insoluble proteins that fibrous protein molecule.
The conjugated proteins are besides this amino acid these proteins contain non protein moieties
along with it which is called the prosthetic group. Nucleoprotein, glycoprotein are some
of the example of this conjugated protein. Now, in case of nucleoprotein nucleic acid
is there as the prosthetic group for the functionality of that particular protein, whereas carbohydrate
moieties are present sometimes as a prosthetic group in the protein molecule for it functionality
like mucin which is present in the saliva.
Sometimes a and it is categorized as a derived protein these are the denatured or degraded
products of the simple and conjugated protein. Examples are the coagulated albumin that is
the egg white fibrin which is formed from the fibrinogen and proteases etcetera are
the example.
Of the derived protein now, when we are I have given you enough example of this protein.
Now, if we see the organization level of this protein then we can categorize the structure
of this protein molecule into different groups, which is called the primary structure, secondary
structure of the protein, tertiary structure of the protein and the quaternary structure
of the protein molecule. Now, if we see the basis of this structure primary structure
is the amino acid sequencing and it is the simple amino acid what I have told you.
I have shown you here that one amino acid one carboxy terminal of this amino acid is
joining with the amino terminal of another amino acid. And in this way they are forming
a big chain resulting one amino terminal free and another carboxy terminal free of this
chain. When we are coming to the secondary structure
it is the folding into the alpha helix and beta sheet or random coil. That means here
besides this primary structure there are additional bonding, which is called the hydrogen bonding
is present. When we are talking about the tertiary structure here 3d folding of a single
polypeptides are there which may be hydrogen or disulfide bond electrostatic or hydrophobic
interactions are also present within this tertiary structure.
And when we are talking about this quaternary structure it is considered to be the more
complex and here the association of different peptide bonds sub units is there and they
are folded within it. And it is having the more complexity and bonding pattern is same
as that of the tertiary structure.
So, if we see the primary structure this is the simple structure secondary structure it
is trying to form a coil, then tertiary structure it is the globular protein and trying to make
more complex structure. And quaternary is the most complex structure which is there
within the protein molecule.
Now, coming to this primary structure I have already discussed this primary structure.
It is the simple peptide bond which is having a very straight chain.
Coming to this secondary structure, Secondary structure of protein indicates the arrangement
of the peptide chain in a space.
Now, see here this is the chain peptide chain and here it tries to be a coil like structure,
when it is trying to be a coil like structure additional this amine containing group has
got some hydrogen bonding with the carboxy end of any another amino acid. And they are
trying to form little bit complex structure and they try to associate the coil within
this confirmation. And that is this coil shape of this alpha helix is held in it is place
by hydrogen bond between the amide group and the carbonyl group of the amino acid.
Now, if this is the black is the carbon, red is the oxygen, nitrogen is the violet R group
is also the dark violet and pale blue is the hydrogen. Then we can find that say this bonding
has got this carboxyl this oxygen is getting bonded with hydrogen. And they are associated
with each other and these amino containing group has got linked with the carboxyl end
with the amide bonding and this way.
They are associating they are making the link when we are talking about the secondary structure
it is called the beta pleated sheet. Now, here the it holds the protein in a parallel
arrangement. So, these are the peptide linking and they are just trying to hold themselves
in the parallel arrangement and it looks like a matrix like structure it has a R group that
extend above and below the sheet. This above and below the sheet it is a typical fibrous
protein such as silk. So, this is one of the examples of the beta pleated protein.
The secondary structure but, we can also get the triple helix it consists of 3 alpha helical
chain it contains a large amount of glycine, proline, hydroxy proline this is a derivatized
product of proline hydroxy lysine. That contain the O H group for hydrogen bonding it is found
in collagen connective tissues skin tendon and the cartilage of the body. Now,
this is the tertiary structure of the protein molecule when we are talking about the tertiary
structure it it gives the specific or overall shape to a protein that involves the interaction
and cross links between the different part of the peptide chain. Hydrophobic and hydrophilic
interactions are there salt bridges are there hydrogen bonding and disulfide bonding that
is the system molecule. When system is the amino acid which is which contains sulphur,
methionine is also another example of sulphur containing amino acid. So, disulfides bridges
when such type of amino acids is present they form the disulfide bridges.
So, when we are talking about this tertiary structure, the secondary structure when it
is getting bent or folded into a more complex 3d structure. We call it as the tertiary structure
here besides this peptide and the hydrogen bonding. We can expect all possible of other
bonding like ionic disulfide Van der Waal hydrophobic and so on. Every reaction every
bonding are possible because it is more and more folded together to form this structure.
Now, here hydrophobic ionic hydrogen bond, disulfide bond etcetera are present for proper
aggregation of the individual protein molecule.
And it forms the tertiary structure. Now, when we are talking about this type of chain
the they are called the peptide chain. Now, in this tertiary structure it is the peptide
chain which is folded bent and they form the complex molecule. Now, in case of quaternary
structure it is more and more complex I have already told. Now, when such peptide more
than one peptide chains are getting associated with each other now say for example, hemoglobin
is one of the example of quaternary structure of the protein here. 2 beta chain and 2 alpha
chains are associated with each other and they are forming the very complex structure.
And when we are talking about this association obviously whatever bonding, whatever complexities
are there so all the peptides are linked together and they form a jumbled like structure. And
here this type of structure is complexities are found in quaternary structure of the protein.
So, quaternary structure is the interaction between the adjacent polypeptide that makeup
the single protein that is hemoglobin collagen etcetera are.
The example of the quaternary structure of the protein molecule. So, I wanted to give
you some idea about the structure and function of different protein. Now, how to quantify
how to know that what is the protein concentration in that particular environment now, we can
measure directly or indirectly. Now, kjeldahl method is one of the technique through which
we can quantify the total organic, nitrogen present in the system and then when we are
multiplying it with 6.25. We are getting the approximate quantification of this protein
molecule which is present in that particular solution.
When this is a dye binding method is also another technique where we are using some
specific dye. Suppose quasi brilliant blue is one of the dye, which is otherwise known
as Bradford method of protein quantification, which has got a direct link with this protein
more the concentration of protein more will be the binding of this dye to that particular
protein more will be the color intensity. And through this quantification standard quantification
method, we can determine the protein content of that unknown solution similarly, Biuret
method, Lowry’s methods are some of the standard quantification method of protein
estimation. And protein concentration determination ultraviolet
method is also one of the techniques where without using any dye any reaction medium.
If we are taking the protein solution colorless protein solution and if we are measuring the
optical density at 280 nano meter. Then we can find the we can quantify that what is
the protein concentration present in that particular solution. It is worth mentioning
that 260 nano meter is the optical density for nucleic acid and 280 nano meter is the
wave length. Where we can quantify the protein solution in any solution, unknown solution
colorless protein if it is presents we can quantify that.
Now, coming to the another important aspect of the protein molecule now, enzyme is one
of the important biocatalyst which is present in every living system. It is worth mentioning
that all enzymes are protein but, all proteins are not enzymes.
Now, here we can find that enzymes are the biocatalyst, which synthesize by the living
cell they are proteinaceous in nature some exception is there except ribozyme. That is
the one enzyme which is non proteinaceous in nature colloidal thermoastable and specific
in action kuhne used the word enzyme to indicate the catalysis of the biological system and
Buchner isolated the zymase enzyme from the yeast.
Now, when we see the chemical nature of this enzyme, we can find that all the enzymes are
invariably proteinaceous in nature I have already told that except that ribozyme that
functional unit of enzyme is known as the holoenzyme. That means the functional unit
is called holoenzyme. Holoenzyme is made up of apoenzyme what is apoenzyme this is the
proteinaceous part of the enzyme and the coenzyme is the non proteinaceous part which is it
may be the organic other part of this body which is not proteinaceous in nature.
Besides this some co factor like prosthetic group coenzyme and metal ions are also playing
a significant role as far as the functionality or the characteristics of protein is concerned.
Now, when we are talking about the prosthetic group, prosthetic groups are the groups that
are tightly bound with the apoenzyme. Apoenzyme is that proteinaceous part of the enzyme.
Now, when we are talking about this coenzyme, coenzyme bound transiently to apoenzyme and
they are separable by dialysis example is vitamin Nicotinamide adenine dinucleotide
that is N A D contains niacin as the vitamin.
Metal ion forms a coordination bond with the side chain of active side concomitantly with
the substrate zinc is a co factor for carboxypeptidase that is the proteolytic enzyme.
Now, if we classify the enzymes based on it is catalytic behavior the entire enzyme can
be divided into 6 major classes. First group is called the oxidoreductases group of enzyme,
second group is the transferases, third group is the hydrolyses, fourth group is the lyases,
fifth group is the isomerases, sixth group is the ligases.
Now, suppose if anyone is talking to you about a particular number suppose 3.2.1.1 E C 3.2.1.1
what does it mean E C means enzyme commission. Now, three means this is the third group of
this enzyme that means that particular is talking about the enzyme which belongs to
this category of hydrolyses. Then it is further classified this enzyme hydrolyses is further
classified based on it is characteristics and the behavior.
And that is the reason this sequence is so important when someone is talking about one
point something that means it is he is talking about the first group of enzyme that is the
oxidoreductases group of enzyme.
Now, let us come to that when we are talking about the oxidoreductases group of enzyme
the name itself is indicating that different type of oxidation reduction reactions are
carried out by this particular enzyme. Most of the intra cellular enzymes belong to this
oxidoreductases group of enzyme. This enzyme involved in the oxidation reduction reaction
example is the succinate dehydrogenase which reduces F A D to F A D H 2 oxidizes succinate
in T C A cycle. I will be coming to this particular step in
some subsequent classes when I will be talking to you about citric acid cycle. So, this is
one of the examples of this oxidoreductases group of enzyme. Now, as a whole if any dehydrogenase
group of enzyme if any kinase group of enzyme are there they belongs to this oxidoreductases
group of enzyme. Now transferases is another group of enzyme
this is the second group of enzyme where this enzyme catalyses the transfer of the functional
group hexokinase. Now, hexokinase is one of the examples where glucose is getting converted
to glucose 6 phosphates with the help of the enzyme hexokinase. What it is doing it is
transferring that glucose that phosphate group from to the 6 position of this hexo. So, that
and it is called the transferases group of enzyme.
Now, when we are coming to this hydrolyses this hydrolyses brings the hydrolytic reaction
of the various compound say for example, the lipases proteases, amylases, cellulases etcetera
are the example of hydrolytic enzyme. Now, they breaks mainly this lipase they are
very specific to this ester bond proteases mainly break the peptide bond amylases and
cellulases. Mainly breaks the glycosidic linkages of the protein molecule. Mainly we are talking
about the lyases enzymes which are specialized in addition to the in addition to double bond
such as C double bond C, C double bond O, C double bond N etcetera. And it is also removes
the water from this reaction say this aconitase group of enzyme I will be talking to you this
group of enzyme when in the subsequent classes.
Coming to this isomerases any type of isomerisation reactions are carried out by this group of
enzyme say for example racemase, racemase is one of the example phosphohexose isomerase
is another example of which belongs to this particular two group of enzyme. And ligases
the formation of bond with A T P cleavage the enzymes catalyzing the synthetic reaction
where two molecules are joined together and one A T P is used that is the D N A ligase.
So, these are some of the example of the different classes and function of enzymes. Now, when
we are comparing what is the importance of this biocatalyst now, when we are comparing
this biocatalyst with any conventional catalyst then we can find that it works efficiently
at higher temperature and higher pressure. It that chemical any chemical catalyst can
work under any high temperature and high pressure. But, in case of biocatalyst it cannot because
it cannot cross the physiological condition of the living cell and living cell cannot
work at very high temperature or else it will collapse. So, slow catalytic reactions are
observed but, here the biocatalysts are highly specific towards it is targeted substrate
molecule and that is the reason the velocity of reaction is much much higher.
compared to any chemical catalyst. Now, say for example, when enzyme catalyses any reaction
at body normal body temperature say carbon dioxide and water in presence of carbonic
anhydrase. It is producing the H 2 C O 3 this in absence of the enzyme 200 molecules of
carbonic acid was formed in an hour in presence of enzyme carbonic anhydrase. This is the
enzyme when it catalysed this reaction 6 lakhs a molecule per second was formed within this.
You just compare and see how efficient this biocatalyst are and that is the reason why
this biocatalysts are occupying such a significant position as far as the living system is concerned
reaction rate accelerates by ten million times enzyme brings down the energy barrier and
facilitate the faster rates.
Now, what is that now a chemical reaction if we consider in any chemical reaction that
is giving the product p so, any chemical reaction.
Suppose a is giving the product p which takes place because of certain faction of the population
of a molecules which gives the instant process enough energy to attain the activation condition
called the transition state. And if we see this is the transition state of substrate
to product formation in absence of enzyme. Now, if we compare the transition state energy
barrier without enzyme and with enzyme then energy barrier with enzyme is very high compared
to the presence of catalyst for any product formation. This is the top of the energy barrier
and separating the reactant that is to the product which is p.
Now, when we are talking about these then we are obviously coming to these that how
a can produce this product this p. There are two ways in which this rate of chemical reactions
can be accelerated. One is that by increasing the heat of this reaction by increasing the
temperature to attain this transition state. Another is the addition of catalyst or biological
catalyst which works mainly on the physiological conditions.
And it is mainly working under and it is converting this substrate or the reactant to the product
molecule. Now, as this particular temperature which is there the transition state the energy
barrier is so high and in compared to this particular enzyme mediated reaction the activation
energy is so less obviously.
The Energy that is the energy barrier which is there for fascinating the energy this reaction
is much favorable and the rate of reaction can be accelerated with the addition of the
enzyme which lower down the activation energy of any process. And this is the reason why
these enzymes are so important and this enzyme how the specificity is so important.
There are several factors which play a very significant role as far as the enzyme reactions
are there are concerned that is the temperature, p H, substrate concentration, binding of specific
chemical that regulate the activity of the enzymes. And the factor alternating alters
the tertiary structure and eventually loss the biological activity of the particular
reaction. So, these are some of the factors which plays a very significant role as I have
told you that proteins are the biological molecules and sometimes depending upon the
nature. It may be heat level; it may be cold levels so depending upon the nature of the
protein catalytic reactions are designed.
Now, if we give some example of this protein, these proteins have a wide range of function,
which includes their role as enzymes hormone antibodies transporters muscle fibers the
lens protein of the eyes feather spider, web rhinoceros, horn, milk, proteins, antibiotics,
mushroom, poisons and myriads other substances having distinct biological activities among
these protein products the enzymes are the most varied.
And thus specialized by chemicals virtually all the cellular reactions are catalyzed by
the enzyme molecule. And with these I think I have tried to give you the overview of this
protein molecule how protein are proteins are formed what are the basic units of this
building block of this protein what are the different characteristics of the amino acids.
So, I have and this primary, secondary, tertiary and quaternary structure of the protein molecule
then I have also tried to give you some idea about this enzymes and how enzyme function.
What are the different parameters which govern the enzyme activity I think you have got some
idea about this protein and it is structure. So, in my next class I will be talking to
you about other macro molecules, which also play a very significant role in the cellular
activities. Thank you very much.