Chemical properties and specificity of Worthington Papain

Papain （Papain）, Also known as papain , It is a proteolytic enzyme . Papain is papaya （Carieapapaya） A low specific proteolytic enzyme contained in , Widely found in the roots of papaya 、 stem 、 In leaves and fruits , It is most abundant in immature milk . The active center of papain contains cysteine , It belongs to sulfhydryl protease , It has high enzyme activity 、 Good thermal stability 、 Natural health and safety , So in food 、 medicine 、 feed 、 chemicals for daily use 、 Leather and textile industries are widely used .

chemical property ：

Papain is a kind of protease in acid 、 Neutral 、 Protease that can decompose protein in alkaline environment . Its appearance is white to light yellow powder , Slightly hygroscopic ; Papain is soluble in water and glycerin , The aqueous solution is colorless or light yellow , Sometimes milky white ; Almost insoluble in B chun、lv Imitation and B mi And other organic solvents . Papain is a sulfhydryl group (-SH) Endopeptidase , It has the activity of protease and esterase , It has a wide range of specificity , For animal and plant proteins 、 Polypeptides 、 ester 、 Amides have strong hydrolysis ability , But it can hardly break down peptone .

Papain zui fit PH value 6～7( commonly 3～9.5 All can ), It also works when it is neutral or acidic , Isoelectric point （pI） by 8.75; The most suitable temperature for papain 55～65℃( commonly 10～85℃ All can ), Strong heat resistance , stay 90℃ It will not be completely inactivated ; Inhibited by oxidants , Reducing substance activation .

features ：

Papain is mainly used for cold resistance of beer （ Hydrolyze the protein in beer , Avoid turbidity caused by cold storage ）、 Meat softening （ Hydrolyzed muscle protein and collagen , Soften meat ）、 Preparation of pre cooked cereals 、 Production of hydrolyzed protein and meat flavor . It is widely used in beer cold resistance and meat softening than other proteases .

AI Meijie Worthington Papain specificity ：

Papain has a wide range of specificity ; It has endopeptidase 、 Amidase and esterase activity . The active site consists of seven sub sites （S 1 -S 4 and  S 1' -S 3'） form , Each subunit can hold one amino acid residue of the substrate （P 1 -P 4 and  P 1' -P 3'）（Schechter And Berger  1967）. Specificity is determined by  S 2 Sub site control ,S 2  A subsite is a host substrate  P 2 Side chain hydrophobic bag . Papain exhibits a specific substrate preference , It is mainly due to a large number of hydrophobic or aromatic residues at this sub site （Kimmel  and  Smith 1954）. stay  S 2 Extra loci preference , Lack of well-defined residue selectivity within the active site .

AI Meijie Worthington Molecular characteristics of papain ：

All mature forms of papain are found in  212  To  218  Between amino acids , And show a strong homology  (Azarkan 2003).X  X-ray structure analysis shows that they use the same three-dimensional folding （Pickersgill  wait forsomeone  1991、O'Hara  wait forsomeone  1995  and  Maes  wait forsomeone 1996）.

Papain is synthesized to have  133  Amino acid  N  The zymogen in the terminal region , This region is not part of the active enzyme （Cohen  wait forsomeone  1986）. Papain precursor gene  prepropapain  Have been cloned and expressed in part or in whole （Cohen  wait forsomeone  1986  and  Choudhury  wait forsomeone 2009）.

Studies on papain ：

Collagenase  (CLS1-4/CLSPA)

Deoxyribonuclease  I (DP/D/DCLS/D2/DPFF/DPRF)

Hyaluronidase  (HSE/HSEP)

Neutral protease  (Dispase, NPRO)

protease  K (PROK)

Trypsin  (TL/TRL/TRL3/TRLS /TRTPCK)

Trypsin inhibitor  (LBI/OI/SI/SIC)

Cell separation optimization system  (CIT)

Hepatocyte isolation system  (HIS)

Neonatal cardiomyocyte isolation system  (NCIS)

Papain dissociation system  (PDS/PDS2)