This document details the definition and functions of enzymes, explaining their role as biological catalysts in biochemical reactions across various organisms. It describes the types of enzymes, their classification based on substrates and reactions, and the importance of cofactors and coenzymes in enzyme activity. Additionally, the document covers enzyme properties, specificity, mechanisms of action, and theories explaining how enzymes interact with substrates.

1. WELCOME TO ENZYMOLOGY

2. Presented by
Dr. N. Sannigrahi, Associate Professor,
Department of Botany,
Nistarini College, Purulia(W.B) India.

3. WHAT IS ENZYME
 The term-Enzyme comes from ‘en=in & zyme’=Yeast coined by F.W Kuhn (1878)
 Enzymes are a biological substance that accelerates the rate of various biochemical
reactions in a living organism without being used up in the reaction. The actions of
enzymes are specific and biodegradable. Enzymes are involved in most of the
biochemical reactions going on in microorganisms, plants, animals, and human
beings. Even though enzymes are produced inside living cells, they can work
actively in vitro, making them useful in industrial processes.
 The assimilation of enzymes in food processing is well known, and devoted research
continues consistently to solve the worldwide food crisis
 Enzymes are catalysts that, within the mild conditions of temperature, pH, and
pressure of the cells, carry out chemical reactions at amazing high rate. They are
characterized by a remarkable efficiency and specificity.
 Unequivocally called-an orderly function of enzymes

4. ENZYME

5. HISTORY OF ENZYME

6. NATURE OF ENZYMES
 All enzymes are globular proteins with the exception of recently discovered RNA
enzymes( Ribozymes). Some enzymes may additionally contain a non-protein group.
Accordingly there are two types of enzymes, simple and conjugate.
 Simple Enzyme: It is an enzyme which is wholly made up of protein. Active site is
formed by specific grouping of its own amino acids. Additional substance or group
is absent, e.g., pepsin, trypsin, unease.
 Apoenzyme + Cofactor= Holoenzyme, Cofactor either Coenzyme, Prosthetic group
or Metal activator
 It is an enzyme(Complex protein enzyme) which is formed of two parts— a protein
part called apoenzyme (e.g., flavoprotein) and a non-protein part named cofactor.
The complete conjugate enzyme, consisting of an apoenzyme and a cofactor, is
called holoenzyme. Active site is formed jointly by apoenzyme and cofactor.
 Cofactor is small, heat stable and dialyzable part of conjugate enzyme. It may be
inorganic or organic in nature. Organic cofactors are of two types, coenzymes and
prosthetic groups.

7. APOENZYME, COENZYME, HOLOENZYME
 Coenzymes are easily separable non-protein organic cofactors. Prosthetic groups are
non-protein organic cofactors firmly attached to apoenzymes, e.g., heme (= haem),
biotin, pyridoxal phosphate. Heme (= haem) is iron containing prosthetic group in
cytochromes, hemoglobin, myoglobin, catalase and peroxidase.
 The last two cause breakdown of hydrogen peroxide to water and oxygen. FMN and
FAD are considered prosthetic groups by some workers while others consider them
to be coenzymes.
 Both coenzyme and prosthetic group take part in group transfer reactions. Prosthetic
group requires a single apoenzyme for picking up the group and transferring the
same. Coenzyme requires two Apo enzymes, one for picking up the group and the
second for transferring the group, e.g., NAD+, NADP+, CoA
 . (a) Coenzyme is essential for bringing the substrate in contact with the enzyme,
 (b) It picks up a product of the reaction, e.g., hydrogen in case of NAD+
(nicotinamide adenine dinucleotide) or NADP+.
 (

8. CLASSIFICATION OF ENZYME
The continuous increase in our knowledge of enzymology needs the proper classification of
These biomolecules for its application. Different approaches have been taken into account
For this classification. Different approaches in this regard as follows:
i. Substrate acted upon enzyme- Duclaux ( 1883) named enzyme by adding suffix –ase
Upon the substrate catalyzed. For carbohydrate, carbohydrases, protein for proteases
And lipase for lipid like this. Maltase for maltose, sucrase for sucrose etc for some
Specific cases.
ii. Type of reaction catalyzed- According to the nature of the reaction catalyzed, suffix –ase
Is added for the same. Hydrolyses for hydrolysis, oxidases for oxidation, dehyrogenases
For dehydrogenation etc.
iii. Substrate acted upon and the type of reaction catalyzed- It can give the clues both for
Substrate utilized and the type of the reaction catalyzed. Succnic dehydrogenase catalyses
Both for the dehydrogenation and Scuccinic acid.

9. iv. Substance that is synthesized- A few enzymes have been named by adding the suffix – ase
To the name of the substance synthesized. Rhodonase that forms rhodonate irreversibly from
Hydrocyanic acid and Sodium thiosulphate .
v. On the basis of the chemical composition of the Enzyme- Based on the chemical compos
-ition, it has been named as follows-
Enzyme molecule being protein only like pepsin, trypsin, Urease, Papain , etc.
Enzyme molecule with protein & cation - Carbonic anhydrase with Zn +2 as cation,
Enzyme molecule with a protein & non-protein organic compound- Iron porphyrin enzymes
Cytochrome C, Flavoprotein enzyme like glycine oxidase, Diphosphothiamin like β-carboxy
lase, Enzymes requiring other coenzymes like amino acid decarboxylase etc.
VI. Overall chemical reaction taken into consideration: According to IUB, precise, descriptive
And informative classification has been offered comprising of two parts in enzyme along with
The additional information regarding the nature of the reaction followed by a distinctive serial
4 digit Numbers to denote the same.

10. i. A recommended name usually short and appropriate for every day use,
ii. A systematic name that identifies the reaction catalyses by it,
iii. A classification number which is used where accurate and unambiguous identification of
Enzyme is required . For example-
The classification number of enzyme , ATP: Creatine Phosphotransferase is EC 2.7.3.2
Where EC= Enzyme Commission,
First number 2 for class name –Transferase,
Second number, 7 for subclass name Phosphotransferase,
Third number , 3 for sub-class name – Phosphotransferase with nitrogen group as acceptor,
Fourth number, 2 for cardinal number of the enzyme within in sub subclass in question.
6 major classes with some examples can have the pleasure of understanding in this regard-
1. Oxidoreductases- It brings about the oxidation and reduction between the two substrates –S
& S′
S (Reduced) + S′ ( Oxidized ) →S ( Oxidized ) + S′ ( Reduced), it may be Oxidases like Cyto
Chrome oxidize or Reductases like Succinate dehydrogenase.

11. Transerfase - Enzyme catalyzed the transfer of a group G , other than Hydrogen between a
Pair of substrate. S & S′ are called transferases.
S-G + S′----- S + S′-G ,
In these are included the enzyme catalyzing the transfer of one-carbon groups, aldehydes or
Ketonic residues, and acyl, glycosyl, alkyl, phosphorous or sulpher containing groups. Some
Important subclasses are Aceyltransaferase. Glycosyltransferases etc.
Acetl-CoA + Choline- CoA + O-Acetylcholine.
Hydrolyses- these catalyses the hydrolysis of their substrates by adding constituents of water
Cross the bond they split. The substrates include ester, glycosyl, ether, peptide, P-N bonds etc.
Different enzymes like Lipase, β- galactosidase are some of the examples.
L- arginine +H2o---- L- ornithine + Urea
Lyases- These are those enzymes that catalyses the removal of groups from substrates by
Mechanisms other than the hydrolysis, leaving double bonds. Form double bonds by the
Elimination of a chemical group or catalyses cleavage by electronic rearrangement.
Carboxylase, Fumarase, PEPcarboxylase, PEPcarboxykinase etc.

12. Isomerases - These catalyze the interconversions of optical, geometric or positional isomers by
Intramolecular rearrangement of atoms or groups. This rearrangement atoms or molecule to
To form a structural isomer is the key aspect of this reaction. Some examples in this regard are
Isomerase, Epimerase, Mutase etc.
L-alanine---------D-alanine in presence of alanine racemase
Ligases or Synthetase- These are the enzymes catalyzing the linking together of two compounds
The energy made available due to simultaneous breaking of a pyrophosphate bond in ATP or
Similar compounds. This category includes enzymes catalyzing reactions forming C-O, C-S
And C-C bonds.
Polymerase is such type of enzymes that link monomers or sub-groups into a polymer such as
RNA or DNA. Glutamine synthetase, Asparagine synthetase, DNA polymerase etc are some of
the Enzymes deserve mentioning in this regard.
In addition to the classification of enzymes, there are different other attributes as far as
Enzyme classification is concerned.

13. PROPERITIES OF ENZYME
 c) The product picked up by a coenzyme is transferred to another reactant.
 Certain workers use the term cofactor for any loosely bound non-protein group.
The organic cofactor is called coenzyme
 Most of the coenzymes are made of water soluble vitamins, В and C, e.g.,
thiamine, riboflavin, nicotinamide, pyridoxine. Inorganic cofactors include ions
of a variety of minerals e.g., calcium, iron, copper, zinc, magnesium,
manganese, potassium, nickel, molybdenum, selenium, cobalt.
 They usually function as activators by forming one or more coordination bonds
with both the substrate and active site of enzyme. Fe2+ is cofactor for catalase.
Chloride ion stimulates activity of salivary amylase. Zinc is required for
carboxypeptidase NAD+ and NADP+ activity.

14. 3D STRUCTURE OF ENZYME

15. PROPERITIES OF ENZYME
 1. Catalytic Property-Extraordinary catalytic power; a small amount of enzyme is
enough to convert large quantity of substrate into products, having turnover
number(Number of substrate molecules converted by one enzyme molecule
/Second) 0.5-600000
 2.Specificity-Specific in their action which may be
 Bond specificity,(Peptide bond)
 Group specificity,(specific bond like peptide bond by pepsin as endopeptidase)
 Substrate specificity,(absolute specificity acts on a particular substrate)
 Cofactor specificity(Specific to cofactor)
 Geometric specificity(Act on similar geometric structure)
 3.Reversibility-Most of the enzymes catalysed reactions are reversible
 4.Temperature sensitive- Increases with the increase of temperature

16. TURN OVER NUMBER OF ENZYMES

17. PROPERITIES OF ENZYME AT A GLANCE

18. PROPERITIES OF ENZYMES
 5. Sensitive to pH-Some enzymes active on low pH(Pepsin Surcease) while other
are high pH(Trypsin, Lipase) but the correct pH is called optimum pH
 6.Colloidal nature-High molecular weight with large surface area, hydrophilic in
nature.
 7. Inhibition of enzyme activity either by Competitive, Non-competitive &
uncompetitive inhibitors reversibly or irreversibly.
 8.Accleration of enzyme activity by ions like Mn, Ni, Cl, Mg etc needed in low
concentration called metal activators-either anti-inhibitors or protectors.
 9.Isoenzymes-more than one enzyme form that can act on the same substrate and
convert into the same product having multiple forms.e.g Malate dehydrogenase
 10. Regulatory enzymes-Sense various metabolic signals and change their
catalytic rates accordingly
 Slowest enzymes- Lysozyme, Fastest enzyme-Carbonic anhydrase

19. ACTIVE SITES
 The enzymes have specific catalytic sites known as active sites or active
centres or catalytic sites or substrate sites. The tertiary or quaternary structure
of the enzymatic proteins are produced due to the folding of the polypeptide
chain(tertiary) or chains(quaternary structure) in such a way or ways to create
active site or sites having correct molecular dimensions and appropriate
topology to accommodate and bind with the specific substrate or substrates.
 The active centre of the enzymes include cofactors.
 The number of the active centres in oligometric enzymes(those possessing a
quaternary structure) may be equal to the number of sub units , i.e. one centre
per unit
 The active sites has two parts-contact site for binding a substrate and a
catalytic site at which the conversion of the bound substrate take place
 Usually, active centre is made up of 12-16 amino acids residue of a polypeptide
chain but it may be larger.

20. IMAGE OF ACTIVE SITE OF ENZYME

21. FUNCTIONAL GROUPS OF ENZYME ACTIVE CENTRE
 In simple enzymes, the role of the functional groups at the contact and catalytic
side sites is assigned to the side chain radicals of amino acids only. But in
conjugated enzymes, the leading part is the Co-factors.
 The following functional enzyme groups take part in catalysis:
 COOH groups of dicaboxylic amino acids and terminal group of the
polypeptide chain,
 NH2 group of lysine and terminal NH2 groups of polypeptide chain
 Guanidine group of arginine.
 Indole group of tryptophan.
 Imidazole groups of histidine.
 OH groups of serine and threonine.
 SH groups of cysteine and disulphide group of cysteine.
 Thioester group of methionine.
 Phenol group of tyrosine.

22. SUBSTRATE SPECIFICITY

23. CONTINUATION-------

24. ABSOLUTE VS GROUP SPECIFICITY
 We have already learnt that the enzymes are specific in their action. Their specificity
 Lies in the fact that they may act- on one specific type of substrate molecule or on a
 Group of structurally –related compounds or on only one of the two optical isomers of
a compound or only one of the two geometrical isomers. According to the four
patterns of enzyme specificity, absolute specificity and group specificity is important.
 ABSOLUTE SPECIFICITY: Some enzymes are capable of acting on only one
substrate. For example, Carbonic anhydrase brings about the union of carbon-di-oxide
with water to form carbonic acid.
H2O + CO2--------H2CO3 ( enzyme, Carbonic anhydrase)
 GROUP SPECIFICITY: Some enzymes are capable of catalyzing the reaction of
Structurally related group of compounds. For example, lactic anhydrase (LDH)
catalyses the interconversions of pyruvic acid or lactic acid and also some other
Structurally related compounds .
CH3 CO.COOH + NADH +H+------ CH3CHOH.COOH
+ NAD+ ( Lactic dehydrogenase)

25. HOW ENZYME WORKS
 In course of action, enzyme must temporarily form a chemical bond or enters
into a transient complex with the substrate whose reaction it catalyses. This
specificity of substrate recognition in both formation of the complex and
catalytic chemical transformation is due to the presence of a special domain on
the surface of the enzyme-active sites.
 A group of amino acids constitute the active site and their side chains form
weak chemical bonds with substrate.
 The nature of the enzyme substrate transformation takes place a paramount
importance & this has been explored by a number of theories-
 Lowering the activation energy of substrates by enzymes-the energy barrier
called activation energy -”extra amount of energy which is a free average
molecule must obtain from some source, so that it can require the activated
state to react with the reactants”

26. ACTIVATION ENERGY

27. SOME EXAMPLES
 1.Activation energy for acid hydrolysis of sucrose is 26Kcal/mole but in
presence of Invertase, its activation energy is -11.5 Kcal/mol . Thus, the
activation energy is lowered by 37.5 Kcal/mol because of 26-(-11.5)=37.5
kcal/mol.
 2.Energy of activation for decomposition of H2O2 is 18.0 Kcal/mol but in the
presence of catalyse, its activation energy is 2.0Kcal/mol . Thus activation
energy is lowered by 16.0 kcal/mol.
 3.In the living cell dynamo of energy production, both the phosphorylation and
dephosphorylation , in presence of ATPase, 10 millions of ATP are converted
to ADP or vice versa every second due to presence of enzyme catalysed
biochemical reactions.

28. MECHANISM ACTION OF ENZYMES

29. ENZYME-SUBSTRATE REACTION

30. ENZYME SUBSTRATE FORMATION
 Two main theories proposed in this regard-
 1. Lock-Key Hypothesis
 2.Induced fit hypothesis
 3.Multisubstrate Reactions
 a. Ordered mechanism
 b. Random mechanism
 c. Ping pong Mechanism
 d. Theorell Mechanism
 LOCK & KEY HYPOTHESIS
 The specific action of an enzyme with a single substrate can be explained using
a Lock and Key analogy first postulated in 1894 by Emil Fischer. In this
analogy, the lock is the enzyme and the key is the substrate. Only the correctly
sized key (substrate) fits into the key hole (active site) of the lock (enzyme).

31. LOCK-KEY THEORY

32. MODE OF LOCK--KEY THEORY
 1.The enzymes temporarily form weak chemical bonds with the substrate.
 2. A group of 3 dimensional amino acid residues constitutes the active site and
their side chains form weak chemical bonds with the substrate.
 3.The conformation of active site is such that it is exactly complementary to the
substrate and so catalyses just as a key fits only its lock not the others.
 4.This theory is supported from the study of competitive inhibition of enzymes
activity. The competitive inhibitors have structural similarity with the substrate
molecules both of which compete for the same active site on the enzyme
molecule. If the active site is rigid and specific for the given substrate ,
reversibility of the reaction would not occur because the structure of the product
is different from that of the substrate and would not fit well.
 This model fails to explain the backward reaction and the stabilization of the
transition state the enzyme achieve.

33. INDUCED FIT HYPOTHESIS

34. INDUCED- FIT HYPOTHESIS
 The induced fit model is a model for enzyme-substrate interaction. It describes that
only the proper substrate is capable of inducing the proper alignment of the active
site that will enable the enzyme to perform its catalytic function. The induced fit
model suggested by Daniel Koshland in 1958.
 The active site of enzyme can be induced by close approach of the substrate (or
product) to undergo a change in conformation(shape) that allows a better
combination between the two(Enzyme and substrate or product).This is called
induced fit hypothesis and here the E-S complex may be ionic, hydrogen and Van der
waals force. The active site continues to change until the substrate is completely
bound, at which point the final shape and charge distribution is determined.
 According to the induced-fit model of enzyme activity, this binding changes the
conformation—or shape—of both the enzyme and the substrate. This brings the
substrate closer to the higher energy transition state needed for the reaction to occur,
for instance, by weakening its bonds so that it can more readily react. Enzymes may

35. CONTINUATION-------
 also speed up a reaction by creating conditions within the active site that are more
conducive for the reaction to proceed than the surrounding cellular environment.
 Once the products of the reaction are formed, they are released from the active site
and the enzyme can be used to catalyze reactions once again.
 An illustration of the competitive inhibitors or substrate analog may also be given.
On contact with the true substrate, all groups are brought into correct spatial
orientation. But attachment of a competitive inhibitor, which is either too “slim” or
too “bulky” induces incorrect alignment.
 As to the sequence of events during conformational changes, 3 possibilities exist.
 a. The enzyme may first undergo a conformational changes, then bind substrate.
 b. An alternative pathway is that the substrate may first be bound and then
conformational changes may occur.
 c. Both the processes may occur simultaneously with further isomerisation to the final
conformation.

36. MICHAELIS-MENTEN EQUATION

37. MICHAELIS-MENTEN EQUATION

38. CONTINUATION----------
 Leonor Michaelis & Maud L. Menten (1913), while studying the hydrolysis of
sucrose by the enzyme, invertase, proposed the theory based on the following
assumptions:
 Only a single substrate & single product is involved,
 The process proceeds essentially to completion,
 The concentration of the substrate is much greater than that of the enzyme of
the system,
 An intermediate ,Enzyme- Substrate complex is formed,
 The rate of decomposition of the substrate i.e proportional to the concentration
of the enzyme substrate complex.
 The theory postulates that the enzyme(E) forms a weakly-bonded complex(ES)
with the substrate (S). this Enzyme -Substrate complex, on hydrolysed,
decomposes to yield the reaction product(P) and the free enzyme(E). The
reaction can be symbolically represented: E＋S→ES→E+P(Reversible)

39. EQUATION

40. ENZYME INHIBITION & FACTORS AFFECT ON ENZYME
INHIBITION
 The interaction between the substrate and the enzyme takes place in a
particular region of the enzyme molecule called the active site.
 In many instances compounds other than the normal substrate for a particular
enzyme-catalyzed reaction may bind to the enzyme’s active site, and this has
a significant effect on the kinetics of the normal reaction.
 One possible consequence of this phenomenon is the inhibition of normal
enzyme activity, and such compounds are therefore called enzyme inhibitors.
 (Usually, the inhibitor is unaltered by its interaction with the enzyme.) In
some instances, the normal substrate (S) and the inhibitor (T) compete with
each other for the active site of the enzyme; the manner in which this affects
the normal kinetics of the reaction. Vmax is not altered by the presence of a
competitive inhibitor, but the KM is elevated.

41. ENZYME INHIBITION-TYPES
 Enzyme inhibition is the decreases in the rate of enzyme-catalysed reaction mediated
by the inhibitors. The inhibitors usually try to prevent the normal binding of enzyme
with the substrate, thus declining the rate of enzyme catalytic pathways. As per as
mode of execution, he inhibitors are of broadly two types-i. Irreversible Inhibition-
Occur by Irreversible inhibitors which combine or destroy a functional group of the
active site required for enzyme activity. Di-isopropyl fluro phosphate(DFP), Cyanide,
Penicillin, aspirin are some inhibitors act as irreversible inhibitions.
 ii. Reversible inhibition-Do not impart any permanent damage of the active site of the
functional groups of the enzyme molecule. If the inhibitors are withdrawn from the
system, enzymatic activities resume to be normal pathways.
 It may be three types-
 a. Competitive Inhibition
 b. Non-competitive inhibition
 c. Uncompetitive inhibition.

42. COMPETITIVE INHIBITION
 A classic example of this form of
inhibition is the competition between
succinic acid and malonic acid for the
enzyme succinic acid dehydrogenase.
In this instance, competition between
these two compounds for the active
site of the enzyme is understandable
in view of their marked chemical
similarity (Fig. 8-9). Succinic acid is
the normal substrate for the enzyme
and, in the absence of the inhibitor, is
converted to fumaric acid.
 (a) Chemical Function of a succinic
acid and malonic acid (b) Malonic
acid is a competitive inhibitor of
succinic acid dehydrogenase.

43. NON-COMPETIVE INHIBITION
 Enzyme inhibition can also be
noncompetitive in that the binding of
the inhibitor to the enzyme cannot be
reversed by increasing the
concentration of the normal substrate.
A common example of negative
inhibition is the action of heavy
metals such as mercury on the active
sites of enzymes containing a reactive
Sulf-hydryl (i.e., -SH) group. In
effect, the presence of the inhibitor
prevents some percentage of the
enzyme present from participating in
normal catalysis. As a result, the
maximum reaction velocity is
depressed, even though the Ku value
remains the same (Fig. 8- 10).

44. UNCOMPETITIVE INHIBITION
 This form of inhibition occur when the
inhibitor binds reversibly only with ES
complex to form ESI ( Enzyme-
Substrate- Inhibitor) complex . ESI is
unable to be converted to any product.
These type of inhibitors are most
effective at high concentration. It
inhibits enzyme catalysis. This type of
inhibition is of rare occurrence with
single substrate and often found in
reductions with 2 or more substrates.
Uncompetitive inhibition is not reversed
by increasing the substrate
concentration . Thus, it is the most
important one where the slope remains
constant but Km value will vary.

45. FACTORS AFFECTING ENZYME ACTIVITY
Different factors play a very important role as far as the enzyme activity is concerned.
The following factors can be addressed in this regard:
i. Substrate Concentration- The rate of enzymatic reaction is enhanced with the increase
of the substrate concentration but up to a certain point, the rate of the enzymatic
action does not change with the further increase of the substrate concentration. This
Point is called Vmax , the maximum velocity where the enzyme is fully saturated with
the substrate. The saturation effect is mostly visible in all cases. In some cases, the
Enzyme activity may decrease at higher substrate concentration called substrate inhibition.
2. Temperature- Enzymes are very sensitive to temperature –thermo labile being protein in
nature. With the increase of temperature, enzyme activity increases and it is maximum at
an optimum temperature ( about 40℃) but with the subsequent increase of temperature
the rate of the enzyme activity decreases and at a maximum temperature, it becomes zero.
The factor by which the velocity increases for a rise of 10 ℃ , called Q10 or temperature
Coefficient value. Both for the increase of 10℃ and decrease of 10℃, both the cases,
Q10 becomes 2. In rare cases, beyond 50-60℃, enzymes become operational except
Taq DNA polymerase.

46. 3.pH- Not only the temperature, enzymes are extremely sensitive to change in pH. Most of
the enzymes becomes functional within a range of 4-10.Very few enzymes becomes
functional above or below this value. Above or below the optimum pH value, the activity
of the enzyme decreases. The optimum pH of an enzyme depends upon the proton donating
groups of the active site of the enzyme. Extreme pH changes lead to enzyme denaturation
that may involve alterations in protein structure and binding of prosthetic group or other
Cofactors leading to their denaturation. Each enzyme have optimum pH like peroxidase has
pH optimum at 6.8
4. Inhibitors- Inhibitors are those substances which decrease the rate of enzyme catalyzed
reactions by combining with the enzyme and preventing the normal binding of enzyme and
Substrate molecule. The inhibitors may be normal or synthetic compounds or the products
Of the reaction itself. Anti-metabolites are the group of the same. Inhibitors may be
reversible or irreversible.
5. Redox Potential- Redox potential of the cell influences the enzyme activity. Oxidizing &
reducing enzymes alter the red ox potential of the cell. As a consequences, the enzymes are
Influenced. The enzyme having readily oxidisable Sulf-hydryl ( -SH) group in their active
Site may bear this property.

47. 6. Other forms- Enzyme activity may be activated by some ions especially cations
present around the active site like Ca+2, K+, Zn +2, Mn+2 etc. In some cases, they are
loosely bound with the enzymes and act as cofactors. In some other cases, not being a part
of the enzyme, in the enzymatic process by modifying either the substrate or the enzyme
molecules. Enzyme activity may also be activated by the anions like Cl- that enhances the
activity of the enzyme, salivary amylase.
MULTIENZYME SYSTEMS
A few examples of complex enzyme systems are known to exist. These are not independent
molecules but occur as aggregates in a mosaic pattern involving several different enzymes.
Pyruvic acid dehydrogenase of E.coli is one such example. The complex molecule has a
Molecular weight 4,800, 000 and consists of three enzymes: 24 molecules Pyruvate
decarboxylase, 24 moles of dihydrolipoic dehydrogenase and 8 subunits of lipoyl reductase
Transaceytylase . Each component of this enzyme complex is so arranged as to provide an
efficient coupling of the individual reactions catalyzed by these enzymes. In other words ,
the product of the first enzyme becomes the substrate of the second and so on.

48. BIOLOGICAL ROLES OF ENZYMES
Enzymes play a very important role in the applications of our daily life and the manifold
Applications of the enzymes are stated below:
i. Wine manufacturing- Enzymology has an opened a horizon in the wine industry like
papain is used in brewing industry as a stabilizer for chill-proof beer. It removes small
amounts of protein that causes the turbidity of the chilled beer.
ii. Cheese making- Since long the animal rennin is employed in making cheese. The enzyme
Rennet is obtained on a commercial scale from the fourth or the true stomach in
unweaned calves.
iii. Candy making- Invertase helps in preventing granulation of sugars in soft-centered candy.
Another enzyme, lactase prevents formation of lactose crystals in ice cream which would
otherwise not allowed the product seem sandy in texture.
iv. Bread whitening- Lipoxygenase is used for whitening the breads.
v. Tenderizing the meat- Hydroxyprolyl residues create bonds in collagen helices which
Contribute the tough and rubbery texture often associated with cooked meat. Protease prior
to cooking can help to overcome the issue.

49. VI .Correcting digestion-When the enzyme are present insufficiently in the body,
digestive disorders are issues. These may be corrected by supplying enzymes and Pepsin,
Papain, amylases like enzymes are helpful in this regard.
vii. Wound healing- Proteolytic enzymes from pig pancreas are used to alleviate skin
diseases like bed sores and sloughing wounds. These enzymes act by destroying proteolytic
enzymes of man, that prevent the healing of such wounds.
viii. Dissolving blood clot- The enzyme, urokinase is manufactured from urine is being
effectively used in the treatment of the blood clot in brain, artery and other circulatory
Diseases. The enzyme , Streptokinase id extensively used in preventing heart attacks as
clots are responsible for fatality in 9 out of 10 cases.
ix. Diagnosing hypertension- It is a kind of radioimmunoassay for diagnosing hypertension
by the activity of rennin which is indirectly calculates the angiotensin-I formed by the
action of rennin.
x. In addition to these, Breaking down the chemicals, destroying acids , amylyzing
bio-chemicals , syrup manufacturing like other products, enzymes are used extensively.

50. References:
1. Google for images,
2. Different open sources of information of WebPages
3. Biochemistry- Lehninger
2. Biomolecules & Cell Biology- Arun chandra Sahu,
3. A textbook of Botany (Vol. II) Ghosh, Bhattacharya, Hait
4. Fundamentals of Biochemistry- Jain, Jain, & Jain,
5.A Textbook of Genetics- Ajoy Paul
DISCLAIMER:
This presentation has been made to enrich open source of learning without any
financial interest. The presenter acknowledges Google for images and other
open sources of information to develop this PPT.

51. THANKS FOR YOUR VISIT