Enzymes are biological catalysts produced by living organisms that speed up chemical reactions without being consumed. They are proteins that contain an active site that binds to specific substrates to catalyze reactions. Enzymes can be classified based on the type of reaction they catalyze or their site of action. Common digestive enzymes include pepsin in the stomach, trypsin in the small intestine, and enzymes from papaya and pineapple such as papain and bromelain which are used to tenderize meat and reduce inflammation.

1. Enzymes
• Enzymes are the organic catalysts produced by living
organisms.
• They are biological catalyst and increase the rate of
chemical reaction.
• They make possible the many complex chemical
reactions that make up life processes. Although
produced by living organisms, enzyme are lifeless.
When isolated, they still exert their characteristic
catalytic effect.

2. • Are specific for
what they will
catalyze
• Are Reusable
• End in –ase
-Sucrase
-Lactase
-Maltase

3. General properties of enzymes
1. Enzyme are colloids and are soluble in water and
dilute alcohol, but are precipitated by concentrated
alcohol.
2. Most enzyme act best at temperature between 35-
40°C, temperature above 65°C, especially in the
presence of moisture, usually completely destroy
them, where as their activity is negligible at 0°C.
3. Certain heavy metals, formaldehydes and free iodine
retard the enzyme activity. Their activity is markedly
affected by the pH of the medium in which they act or
by the presence of other substances in this medium.
4. They are highly selective in their action.

4. 5.The enzyme are proteins that range in molecular
weight from about 13,000 to as much as 8,40,000
Dalton.
6.Minute quantities of enzymes are required to complete
a chemical reaction.

5. Chemical nature of enzymes
• Many enzymes are inactive when first
produced. Such enzymes in inactive form are
called pro-enzymes or zymogens.
• They are inactive because the active site is not
exposed and unable to bind with substrate.
Later by the action of essential coenzymes or
activator they made active.

7. • Enzymes often occur in combination with
inorganic and organic substances that have an
important part in the catalytic action. If these
are non protein organic compounds known as
coenzymes. If they are inorganic ions, they are
referred as activator.
• Coenzymes are integral part of enzyme
system. Several vitamins, thiamine chloride,
riboflavin, nicotinic acid are recognized as
having a co-enzymatic function.

8. • Both are collectively called cofactors. The cofactors
bound to the protein part of enzyme tightly. In this
case cofactor is termed as prosthetic cofactor or
prosthetic group.
• In globular structure of enzymes, one or more
polypeptide chains twist and fold, brining together a
small number of amino acids to form active site.
• Active site is that location on the enzyme where the
substrate binds. Enzyme and substrate fails to bind if
there shape does not match exactly.

9. Enzyme energy activation
Without Enzyme
With Enzyme
Free
Energy
Progress of the reaction
Reactants
Products
Free energy of activation

10. Enzyme-Substrate Complex
The substance
(reactant) an
enzyme acts
on is the
substrate
SUBSTRATE JOINS Enzyme

11. Enzyme-lock and key theory
• first postulated in 1894 by Emil Fischer.

12. Induced Fit Theory:
• determining the final shape of the enzyme and
that the enzyme is partially flexible.
• This explains why certain compounds can bind
to the enzyme but do not react because the
enzyme has been distorted too much.
• Only the proper substrate is capable of
inducing the proper alignment of the active
site.

13. • The substrate is
represented by the
magenta molecule,
the enzyme protein is
represented by the
green colour.
• The protein chains are
flexible and fit around
the substrate.

14. Classification of enzymes
There are several methods for classification of
enzymes few are given below.
• Classification on the basis of reaction they
control
• Classification on the basis of site of action
• Classification on the basis of nature of
substrate

15. 1. Classification on the basis of
reaction they control
• Six major classes are recognized
1. Oxido-reductases
2. Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases

16. 1. Oxido-reductases: Catalyzing oxido-reductions
between two substances.
e.g. peroxides, glucose 6-phosphate
2. Transferases: Catalyzing a transfer of group,
other than hydrogen, between a pair of
substrates. e.g. transmethylase, transaminase
3. Hydrolases: Catalyzing hydrolysis of esters, ether,
peptide, glycosyl, acid-anhydride, C-C, C-halide or
P-N bonds. e.g. carbohydrases, lipases,
proteinases

17. 4. Lyases: catalyzing removal of groups from
substrates by mechanisms other than
hydrolysis, leaving double bond. e.g. Fumerase
5. Isomerases: catalyzing inter conversion of
optic, geometric or positional isomers. e.g.
G-6-phosphate isomerase
6. Ligases: Catalyzing linkage of 2 compounds
coupled to the breaking of a pyrophosphate
bond in ATP or a similar compound. e.g.
Acetyl Co-A carboxylase.

18. • Because the nomenclature of enzymes was
rather well established prior to the
promulgation of this system, the well known
trivial names are still ordinarily employed in
the pharmaceutical literature. Those
encountered with some frequency are:
1. Esterases: including lipase, phospholipase,
acety cholinesterase and others

19. 2.Carbohydrases: including diastase, lactase,
maltase, invertase, cellulase, lysozyme etc.
3.Nucleases: including ribonuclease,
desoxyribonuclease, nucleophosphatase etc.
4.Nuclein deaminases: including adenase,
adenosine deaminase etc.
5.Amidases: including arginase, urease etc.
6.Proteolytic enzymes: including pepsin, trypsin,
chymotrypsin, papin, fibrinolysin,
streptokinase, urokinase etc.

20. 2. Classification on the basis of site of
action
• Enzyme are classified into two groups
1. Endo-enzymes: these enzymes act inside the
cells also called intracellular enzymes. These
enzyme are responsible for synthesis of cell
components, production of energy and
metabolism. Examples are synthetase,
isomerase and phosphorylase

21. 2. Ex-oenzyme:
• They act out side the cell and called
extracellular enzymes.
• Such enzymes are digestive in their function
i.e. break down complex molecule into small
units. Examples proteases, lypases, amylases.

22. 3. Classification on the basis of nature
of substrate
I) The amylolytic Enzyme or carbohydrates :
Examples:
• Diastase and amylase: term applied to 2 well
known amylolytic enzymes salivary diastase or
ptyalin and pancreatic diastase or amylopsin are
found in digestive tract of animals
• Malt diastase: it is formed during the germination
of barley grains and converts starch into lactose.
• Invertase or sucrase: found in yeast and intestinal
juices. It brings hydrolysis of sucrose into glucose
and fructose.

23. • Maltase: cause conversion of maltose into
glucose.
• Zymase: fermentation enzyme cause
conversion of mono-saccharides into alcohol
and carbon dioxide.

24. II) The esterases:
Examples:
• Lipase: it is a lipolytic enzyme widely distributed
in animal and vegetable kingdoms. Found in
pencreatic juice of animals and oily seeds.
• Pectase: splits pectin into pectic acid and methyl
alcohol.
• Steapsin: it is lipolytic enzyme capable of methyl
alcohol.
• Urease: obtained from soybeans and used in
laboratory reagent for converting urea to
ammonia.

25. III) The protolytic enzymes:
Examples:
• Pepsin: is protolytic enzyme found in the
gastric juice and active at pH 1.8.
• Trypsin: it is formed when the proenzyme
trypsinogen is acted on by the enterokinase of
the intestinal juice. It is more active than
pepsin and converting proteoses and
peptones into polypeptides and amino acids.
It is active at pH 8.

26. • Erepsin: it is found in intestinal juices. It converts
proteoses and peptones into amino acids.
• Rennin: it is a coagulating enzyme present in the
mucous membrane of the stomach of mammals.
It curdles the soluble casein of milk.
• Papain: it is a mixture of active proteolytic
enzymes found in the unripe fruit of the papaya
tree.
• Bromelain: protein digesting and milk-clotting
enzyme obtained from the juice of the pineapple
plant.

27. IV) The oxidizing enzymes:
Examples:
• Peroxides: are widely distributed in plants,
they bring about the oxidation reactions that
cause the discoloration of bruised fruits.
• Thrombin: converts the fibrinogen of the
circulating blood into the insoluble fibrin of
the blood clot.
• Zymase: splitting of mono-saccharides by
oxidation.

28. Pepsin
• Biological Source:
Pepsin is obtained from
the stomach of the ox
(Bos taurus), the sheep
(Ovis aries), or the hog
(Sus scrofa), the
mucous membrane
being the part used.

29. PREPARATION
• Pepsin is prepared by digesting the minced
stomach linings with HCl acid. This solution is
clarified, partially evaporated, dialyzed,
concentrated and either poured on glass
plates to dry, thus forming scales papsin, or
carefully evaporated in a vacuum, forming
spongy pepsin.

30. Description:
• Its a yellowish-white amorphous powder or
thin, pale yellowish, somewhat transparent
scales, with faint odour and slight saline or
acidulous taste, but no indication of
decomposition; should not be hygroscopic. It
invariably contains some rennin; its solutions,
therefore, will coagulate milk. Incompatible
with alkalis, alcohol, and heat renders it inert.

31. Applications
• Pepsin is administered to assist gastric digestion.
It is a proteolytic enzyme and should preferably
be given after meals and followed by a dose of
HCl acid. Usually dose is 500mg. It is often
combined with pancreatin in product
formulations.
• Pepsin has a long history of use in medicine, but
its actual beneficial contribution is poorly
documented.
• Pepsin may be given to help gastric digestion in
those in whom from old age or long illness the
secretion of gastric juice is deficient.

33. PAPAIN
Biological source:
Papain is the dried and purified
latex of the fruit of Carica
papaya Linne (Family.
Caricaceae).
• Papain is a substance which
contains a mixture of proteolytic
enzymes found in the unripe
fruit of papaya tree.
• It is also referred to as
papaya proteinase

34. DISTRIBUTION:
• The papaya tree is indigenous to tropical
America and is cultivated in Sri Lanka,
Tanzania, Hawaii, and Florida.

35. PHYSICAL DESCRIPTION
• It attains a height of about 5
or 6 meters. The fruit grows
to a length of about 30 cm
and a weight of 5 kg. The
epicarp adheres to the
orange-colored, fleshy sarco
carp, which surrounds the
central Cavity. This cavity
contains a mass of nearly
black seeds.

36. Isolation of papain
• The full grown but unripe fruit is subjected to
shallow incisions on the 4 sides. The latex
flows freely for a few seconds, but soon
coagulates. After collection, the coagulated
lumps are shredded and dried by the sun or by
the use of artificial heat. Incisions and
collections are made at weekly intervals as
long as the fruit exudes the latex. The crude
papin is purified by dissolving in the water and
precipitating with alcohol.

38. Chemical constituents
• Papain acts in acid, neutral, or alkaline media.
• Papain contains several enzymes such as
Peptidase, capable of converting proteins into
dipeptides and polypeptides.
• A rennin like, coagulating enzyme that acts on
the casein of milk.
• An amylolytic enzyme; pectase, which
converts carbohydrates molecules into simple
units i.e. monosaccharide.

39. Uses
• Papain is used as a digestant for proteins because
it has an action much like that of pepsin. The best
grade of papain digests 300 times its own weight
of egg albumin.
• It is employed to relieve the symptoms of
episiotomy
• It is used to tenderize meats. In the meat packing
industry, papain is used extensively for
tenderizing beef.
• PROPRIETARY PRODUCTS. Caroid and Papase.

41. BROMELIN
• Biological source:
Bromelain or bromelin is a protein
digesting and milk-clotting enzyme
obtained from the juice of the pineapple
plant, Ananas comosus (Linne) Merr
(Family. Bromeliaceae). Although this
enzyme can appear in the juice of the fruit,
it can also occur in the stem of the plant. It
differs from papain because it is obtained
from both the ripe and unripe fruits.

44. Extraction

45. Uses:
• Bromelain is used as adjunctive therapy to reduce
inflammation and edema and to accelerate tissue
repair, especially following episiotomy.
• Bromelain is also employed in the production of
protein hydrolysates,
• In tenderizing meats in the leather industry.
• PRESCRIPTION PRODUCT: ‘’Ananase’’.