Papain, also known as papaya proteinase I, Is a cysteine protease enzyme present in papaya (Carica papaya) and mountain papaya.

1. Papain
By
Junaid ikram

2. Papain:-
Papain, also known as papaya proteinase I,
Is a cysteine protease enzyme present in papaya
(Carica papaya) and mountain papaya.

3. STRUCTURE:
The globular protein, the papain is
a single chain protein with molecular
weight of 23,406 DA and consists of
212 amino acid with four disulphide
bridges.

5. Papain family:-
Papain belongs to a family of related proteins with a
wide variety of activities, including endopeptidases,
aminopeptidases, dipeptidyl peptidases and enzymes
with both exo- and endo-peptidase activity.
 Members of the papain family are widespread, found
in baculoviruses, eubacteria, yeast, and practically all
protozoa, plants and mammals.

6. The proteins are typically lysosomal or secreted, and
proteolytic cleavage of the propeptide is required for
enzyme activation, although bleomycin hydrolase is
cytosolic in fungi and mammals.
Papain-like cysteine proteinases are essentially
synthesised as inactive proenzymes (zymogens) with
N-terminal propeptide regions.

7. The activation process of these enzymes includes
the removal of propeptide regions, which serve a
variety of functions in vivo and in vitro.

8. Amino acid residues within the pro-region mediate
their membrane association, and play a role in the
transport of the proenzyme to lysosomes.
Among the most notable features of propeptides is
their ability to inhibit the activity of their cognate
enzymes and that certain propeptides exhibit high
selectivity for inhibition of the peptidases from which
they originate.

9. Isolation of papain
The full grown but unripe fruit is subjected to shallow
incisions on the four 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
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 alchohol.

11. Chemical constituents:
Papain contain several enzymes
Peptidase: capable of converting into dipeptides
and poly piptides.
A renin like coagulation enzyme that acts on the
casein of milk
An amylolytic enzyme which converts
carbohydrates molecules into simple units.

12. Function:-
The mechanism by which papain breaks peptide
involves the use of a catalytic triad with a
cystine.
This cysteine then performs a nucleophilic attack on
the carbonyl carbon of a peptide backbone.
This forms a covalent acyl-enzyme intermediate and
frees the amino terminus of the peptide

13.  The enzyme is deacylated by a water molecule and
releases the carboxy terminal portion of the peptide.
Papain is a relatively heat-resistant enzyme, with an
optimal temperature range of 60 and 70 °C.

14. Developed the technical knowhow for the product.
The process flow chart is as under.
Collection
of latex
Cleaning
and sieving
Mixing and
drying
Packing

15. Uses:-
Papain breaks down tough meat fibres.
Papain can be used to dissociate cells in the first step
of cell culture preparations.

16. A ten-minute treatment of small tissue pieces (less than 1
mm cubed) will allow papain to begin cleaving the
extracellular matrix molecules holding the cells together.
After ten minutes, the tissue should be treated with a
protease inhibitor solution to stop the protease action.
 Left untreated, papain activity will lead to complete lysis of
the cells.
The tissue must then be triturated (passed quickly up and
down through a Pasteur pipette) to break up the pieces of
tissue into a single cell suspension.

17. Papain is the main ingredient of Papacarie, a gel used
for chemomechanical dental caries removal.
It does not require drilling and does not interfere in the
bond strength of restorative materials to dentin.
Papain has been known to interfere with urine drug
tests for cannabinoids.
 It is found in some drug detox products.

18. Production;-
Papain is usually produced as a crude, dried
material by collecting the latex from the fruit of
the papaya tree.
The latex is collected after scoring the neck of
the fruit, where it may either dry on the fruit or
drip into a container.
This latex is then further dried. It is now
as a dried, crude material.

19. A purification step is necessary to remove
contaminating substances.
This purification consists of the
solubilization and extraction of the active
papain enzyme system through a
government-registered process.
This purified papain may be supplied as
powder or as liquid.