This document discusses proteases, which are enzymes that catalyze the breakdown of proteins. It describes the seven main classes of proteases based on their catalytic residue: serine, cysteine, threonine, aspartic, glutamic, metallo, and asparagine peptide lyases. Each class is explained along with examples. The document also covers protease structure, classification based on pH, mechanisms of action, and various industrial and medical uses of proteases.

1. Industrial fungal metabolites
Enzymes-Proteases
V.S.Patil
Associate Professor, Department of Botany
Shri Shivaji College of Arts, Commerce,& Science
Akola

2. •A protease (also called a peptidase or proteinase) is
an enzyme that catalyzes (increases the rate of) proteolysis,
the breakdown of proteins into smaller polypeptides or
single amino acids. They do this by cleaving the peptide
bonds within proteins by hydrolysis, a reaction where water
breaks bonds.
•Proteases are involved in many biological functions,
including digestion of ingested proteins, protein
catabolism (breakdown of old proteins), and cell signaling.
•Proteases can be found in all forms of life and viruses.
•Without additional helping mechanisms, proteolysis would be
very slow, taking hundreds of years.

3. Structure

4. Classification-
1.Serine proteases - (using a serine alcohol)- Serine proteases (or serine
endopeptidases) are enzymes that cleave peptide bonds in proteins, in
which serine serves as the nucleophilic amino acid at the (enzyme's) active site. They
are found ubiquitously in both eukaryotes and prokaryotes. Serine proteases fall into
two broad categories based on their structure: chymotrypsin-like (trypsin-like)
or subtilisin-like.
Uses-1.Coagulation factor levels may be required in the diagnosis of hemorrhagic or
thrombotic conditions.2.Fecal elastase is employed to determine the exocrine activity of
the pancreas, e.g., in cystic fibrosis or chronic pancreatitis.3.Serum prostate-specific
antigen is used in prostate cancer screening, risk stratification, and post-treatment
monitoring.4.Serine protease, as released by mast cells, is an important diagnostic
marker for type 1 hypersensitivity reactions (e.g. anaphylaxis). More useful than
e.g. histamine due to the longer half-life, meaning it remains in the system for a
clinically useful length of time.

5. 2.Cysteine proteases - (using a cysteine thiol) It is also known as thiol
proteases. They are enzymes that degrade proteins.
These proteases share a common catalytic mechanism that involves
a nucleophilic cysteine thiol in a catalytic triad or dyad. They are found
in fruits including the papaya, pineapple, fig and kiwifruit. The
proportion of protease tends to be higher when the fruit is unripe.
Cysteine proteases are used as an ingredient in meat tenderizers.
This protease classification system counts 14 superfamilies.
Uses- 1.In plants they are important in growth and development and in
accumulation and mobilization of storage proteins such as in seeds.
2. they are involved in signalling pathways and in the response
to biotic and abiotic stresses.
3. They are responsible for senescence and apoptosis (programmed cell
death), MHC class II immune responses, prohormone processing,
and extracellular matrix remodeling important to bone development.
4. They may also lead to accelerated collagen and elast in degradation at
sites of inflammation in diseases such as atherosclerosis and emphysema.

6. 5. They are resistance to acid digestion, allowing possible oral
administration.
6. They are used as a feed additives for livestock to improve the
digestibility of proteins and nucleic acids.
7. In several traditional medicines, the fruits or latex of the papaya,
pineapple and fig are widely used for treatment of intestinal
worm infections both in humans and livestock.

7. 3.Threonine proteases - (using a threonine secondary alcohol)-
Threonine proteases are a family of proteolytic enzymes harbouring
a threonine (Thr) residue within the active site. The prototype members
of this class of enzymes are the catalytic subunits of the proteasome,
however the acyltransferases convergently evolved the same active
site geometry and mechanism.
Five families belonging to two separate superfamilies are currently
recognised.

8. 4.Aspartic proteases - (using an aspartate carboxylic acid)
Aspartic proteases are a catalytic type
of protease enzymes that use an activated water molecule
bound to one or more aspartate residues for catalysis of their
peptide substrates. Eukaryotic aspartic proteases
include pepsins, cathepsins, and renins.
Five superfamilies (clans) of aspartic proteases are known,
each representing an independent evolution of the same active
site and mechanisms.

9. 5.Glutamic proteases - (using a glutamate carboxylic acid)
Glutamic proteases are a group
of proteolytic enzymes containing a glutamic acid residue
within the active site. This group of proteases are found
primarily in pathogenic fungi affecting plant and human.
Structure contain the active site of a catalytic dyad, glutamic
acid (E) and glutamine (Q), which give rise to the
name eqolisin. There are two independent families of glutamic
proteases (G1 and G2).

10. 6.Metalloproteases - (using a metal, usually zinc)
A metalloproteinase, or metalloprotease, is
any protease enzyme whose catalytic mechanism involves
a metal. It plays a significant role in the fusion of muscle cells
during embryo development, in a process known
as myogenesis.
Their are two types
1.Exopeptidases, metalloexopeptidases.
2. Endopeptidases, metalloendopeptidases

11. 7.Asparagine peptide lyases - using an asparagine to perform
an elimination reaction (not requiring water)
Asparagine peptide lyase are one of the seven groups in
which proteases, also termed proteolytic enzymes, peptidases,
or proteinases, are classified according to their catalytic
residue.
Types- Viral coat proteins
Autotransporter proteins
Intein-containing proteins

12. Classification based on optimal pH.
Alternatively, proteases may be classified by the optimal pH in
which they are active:
1.Acid proteases
2.Neutral proteases involved in type 1 hypersensitivity. Here,
it is released by mast cells and causes activation.
of complement and kinins. This group includes the calpains.
3.Basic proteases (or alkaline proteases)

13. Mechanisms:
1.Aspartic, glutamic and metallo- proteases activate a water
molecule which performs a nucleophilic attack on the peptide
bond to hydrolyse it.
2.Serine, threonine and cysteine proteases use a nucleophilic
residue (usually in a catalytic triad). That residue performs a
nucleophilic attack to covalently link the protease to the
substrate protein, releasing the first half of the product. This
covalent acyl-enzyme intermediate is then hydrolysed by
activated water to complete catalysis by releasing the second
half of the product and regenerating the free enzyme.

15. Uses
1.Proteases are involved in digesting long protein chains into shorter
fragments by splitting the peptide bonds that link amino acid residues.
Some detach the terminal amino acids from the protein chain
(exopeptidases, such as aminopeptidases, carboxypeptidase A); others
attack internal peptide bonds of a protein (endopeptidases, such
as trypsin, chymotrypsin, pepsin, papain, elastase).
2. laundry detergents.
3. in the bread industry in bread improver. for quicker preparation of
dough, its gluten is partially hydrolyzed by a heat-labile fungal protease
because of its early inactivation in subsequent baking.
4. A variety of proteases are used medically both for their native
function (e.g. controlling blood clotting) or for completely artificial
functions (e.g. for the targeted degradation of pathogenic proteins).
5. Highly specific proteases such as TEV protease and thrombin are
commonly used to cleave fusion proteins and affinity tags in a controlled
fashion.
ation

16. 6. In the food industry, proteases are utilized for modification,
palatability, and storage life of all available sources of proteins.
7. In meat tenderiz
8.Food and Feed Industry-During cheese production from
milk, proteases are added to hydrolyze kappa casein to prevent
coagulation by stabilizing micelle formation.
9. pharmaceutical drug formations.
10. fortification of soft drinks and juices
11. Waste Management
12. Leather Industry-in the soaking, bating, and dehairing phase of
preparing skin and hides.