Enzymes are proteins that speed up chemical reactions without being used up in the process. They have an active site that binds to specific substrates to catalyze reactions. Enzyme activity is affected by factors like temperature, pH, and substrate/product concentration. Enzymes play essential roles in digestion, cell signaling, movement, and other processes. They are also used clinically for treating digestive disorders, stopping bleeding, and diagnosing conditions like diabetes by testing for enzymes in the blood. Abnormal enzyme levels can indicate diseases of organs like the heart, liver, and pancreas.

1. ENZYMES

2. ENZYMES
 Are chemical substance which hastens chemical
reaction without being affected in the process.
 Are secreted by living cells, and are complex organic
chemical compounds with definite structure.
 Like the inorganic catalysts, enzymes have the
remarkable property of speeding up chemical reactions
without being themselves affected in the process. As a
result they can be use over and over again.

3.  Catalysts or enzymes are responsible for different
biological changes.
 They make up the largest and most highly specialized
class of proteins.
 The catalytic efficiency of enzyme is so high that per
mole is around 10,000 to 10,000,000 moles of
substrate per minute.
 The catalytic action of enzymes is the key to their
importance, for by facilitating chemical changes,
enzymes make possible the continuous replacement
and renewal processes of all living organisms.

4. NOMENCLATURE
 With the increasing number of known enzymes, it is
essential that a more systematic nomenclature be
adopted. Therefore, enzymes are now designated by
the suffix ase proceed by the term which indicates
the following:
1. General nature of the substrate ex. Lipase-acting
upon liquid.
2. Actual name of the subsrate ex. Sucrase- acting on
sucrose.
3. Type of reaction catalyzed ex. Oxidase-catalyzes
oxidation.
4. Combination of several of these designation ex.
Xanthine oxidase-catalyzes oxydation of xanthine.

5.  In case of the hydrolytic enzymes, the suffix
adjective lytic is used.
 amylolytic, lipolytic, proteolytic enzymes
 The inactive form of enzyme is the pro-enzyme or
zymogen. The suffix ogen is affixed to the name of
the active enzyme.
pestrinogen, trypsinogen, reninogen
-they exhibit the property of true enzyme only after
they are activated by suitable hydrogen ion
concentration or by an organic activator called kinase.

6. CLASSIFICATION
1. Oxido-reductases (cause oxidation
reduction reaction)
1.1– acts on –CH-OH (secondary alcohol)
1.2- acts on -C=O (ketone)
1.3- acts on –CH=C- (alkene)
1.4- acts on -CH-NH2 (primary amine
1.5- acts on -CH-NH- (secondary amine)
1.6- acts on NADH3 NADPH

7. 2. Transferases (transfer functional
group)
2.1- one carbon group
2.2- aldehyde or ketonic group
2.3- acyl group
2.4- glycerol groups
2.5- phosphate group
2.6- S-containing group

8. 3. Hydrolases (causes hydrolysis)
3.1- esters
3.2- glycosidic bonds
3.3- peptide bonds
3.4- other C-N bonds
3.5- acyl anhydrides

9. 4. Lyases (addition of double bonds)
4.1- C=C (alkene)
4.2 C=O (ketone)
4.3 C=N (cyanide)
5. Isomerases (isomerization reaction)
5.1- Racemases

10. 6. Ligases (formation of bonds with
ATP cleavage)
6.1- C-O
6.2- C-S
6.3- C-N
6.4- C-C

11. FUNCTIONS OF ENZYMES
Enzymes are indispensable for signal
transduction and cell regulation,
often via kinases and phosphatases.
Generate movement, with myosin
hydrolyzing ATP to generate muscle
contraction and also moving cargo
around the cell as part of the
cytoskeleton.

12. Enzymes are also involved in more
exotic functions, such as luciferase
generating light in fireflies.
Viruses can also contain enzymes for
infecting cells, such as the HIV
integrase and reverse transcriptase,
or for viral release from cells, like
the influenza virus neuraminidase.

13.  An important function of enzymes is in the
digestive systems of animals. Enzymes such as
amylases and proteases break down large
molecules (starch or proteins, respectively) into
smaller ones, so they can be absorbed by the
intestines. Starch molecules, for example, are
too large to be absorbed from the intestine, but
enzymes hydrolyze the starch chains into smaller
molecules such as maltose and eventually glucose,
which can then be absorbed. Different enzymes
digest different food substances.

14. FACTORS AFFECTING THE RATE OF
ENZYME ACTION:
1. Concentration of Enzyme and its substrate: other
conditions being constant, the rate of reaction depends
on the concentration of enzyme and substrate.
2. The effect of Temperature: on enzyme reaction is
two. A region high temperature in which the rate
decreases with increased temperature due to the
thermal inactivation of the enzyme (denaturation).
Optimum temperature 37˚C-40˚C

15. 3. Effect of pH: most enzymes have a
characteristic pH at which the activity
is maximal. The pH activity profiles of
enzymes are not always shaped. They
may even be rectilinear.
4. The effect of Time: Time is
important element in defining other
conditions which regulate the rate of
enzyme motion.

16. 5. The products of Reaction: the rate
enzyme action decreases on the product
of reaction increases. This is due to the
reversibility off enzyme action.
Sucrase
Sucrose Glucose + Fructose

17. 6. Light and other physical agents: light rays
affect the activity of enzymes. Blue and red
lights increases the activity of salivary
amylase, while ultraviolet rays and radium
exert inhibitory effect. Violet shaking
destroys the enzymes by causing
denaturation.
7.Chemical agents: some chemical agents
accelerate enzyme action. Ex. If salivary
amylase is (freed from sodium chloride) it
becomes inactive.

18. PROPERTIES OF ENZYMES
1. Molecule composed from one or more
protein chains
2. Catalytic action; elevated catalytic power
3. Reduction of activation energy
4. Elevated specificity
5. Active site
6. Inhibition by specific molecules

19. Structure and Function of an Enzyme

20. Enzymes are large proteins that speed up
chemical reactions. In their globular structure,
one or more polypeptide chains twist and fold,
bringing together a small number of amino acids
to form the active site, or the location on the
enzyme where the substrate binds and the
reaction takes place. Enzyme and substrate fail
to bind if their shapes do not fit each other.
This ensures that the enzyme does not
participate in the wrong reaction. The enzyme
itself is unaffected by the reaction. When the
products have been released, the enzyme is
ready to bind with a new substrate.

21. CLINICAL APPLICATION OF ENZYMES
*Medical and clinical uses of enzymes:
1. Drugs for digestive disorders
-Some digestive enzymes such as amylases are often
used as s components of drugs to cure digestive disorders.
2. Deworming medicines
-The plant proteases like ‘papain’ (from papaya) and
‘ficin’ (from fig) lire used as deworming medicines for
humans and domestic animals.

22. These enzymes are not inhibited by the
secretions of the worms and cause digestion of
the worms.
3. Enzymes to stop bleeding
-The enzyme ‘thrombin’ obtained from beef
plasma is used topically to stop bleeding during
operations and after tooth extraction. The
enzyme converts fibrinogen to fibrin and small
peptides, which are then insolubilized causing
blood to clot.

23. 4. Enzymes as surface disinfectants
-‘Trypsin’ has been used in cleaning away
thick, purulent (full of pus) masses in surface
infections and in emphysema (enlargement of
vesicles of lungs) associated with pleural
pneumonia. The area cleaned by its digestive
action heals much more rapidly than
untreated area. The two other enzymes ‘ficin’
and ‘streptodornase’ are also used sometimes
as wound debridement.

24. 5. Diagnosis of diabetes
-‘Glucose oxidase’ in combination with
‘peroxidase’ is used for colorimetric
determination of glucose in blood. This test
generally conducted to determine the level
of blood sugar thus leading to diagnosis of
diabetes.

25. ENZYMES AND RELATED DISEASES
 Acid Phosphatase- some prostatic disease
 Alanine aminotransferase (ALT)- Liver, Heart
diseases
 Aldolase- some muscle diseases
 Alkaline Phosphate- Liver and Bone diseses
 Amylase- pancreatic diseases
 Angiotensin- Converting enzyme (ACE)- Active
sarcoidosis
 Aspartate aminotransferase (AST)- Heart, Liver
diseases

26.  Cholinesterase (psuedocholinesterase)-acute
organophosphorus poisoning
 Creatine Kibase (CK or CPK)- Heart, Muscle
disease
 Gamma-Glutamytransferase (GGT)- Liver
disease, alcohol rehabilitation
 LactateDehydrogenerase (LDH)- Heart,
Liver, Brain disease
 Lipase- Pancreatitis
 Lysozymes- some acute luekemias