Papaya peptidase

After Schack named the most basic proteinase of the latex papaya peptidase A, many other names have been used for this enzyme, namely, papaya peptidase IL papaya proteinase ILL papaya proteinase A. and papaya proteinase Q (281. Most recently, it has been suggested that it should be called caricain [29]. 

G. W. Robinson. Isolation and characterization of papaya peptidase A from commercial chymopapain. Biochemistry 14 36/95 (1975). 

L Polgfr. Iso] ad on of highly active papaya peptidases A and B from commercial Chymopapain. Stocknn. Biophyt Aclu 658 262 (1981),... 

In addition to papain, at least two other proteolytic components have been shown to be present in crude extracts of commercial papaya latex, namely, chymopapain (1,27) and papaya peptidase A (28). Since these isolated enzymes are not used commercially, they will not be considered further. 

Caricain was purified for the first time in 1967 by Schack, who called this enzyme papaya peptidase A [19]. Robinson [20] showed it to be one of the components in commercial chymopapain, and the same enzyme was probably called chymopapain C by Clagget et al. [21]. Schack also mentioned a minor but highly active protein component with an intermediate basicity between chymopapain and papaya peptidase A, which was called papaya peptidase B by Lynn [22]. 

B. S. Baines and K. Brocklehurst. Isolation and characterization of the four major cysteine-proteinase components of the latex of Carica papaya L. Reactivity characteristics towards 2,2 -dipyridyl disulfide of the thiol groups of papain, chymopapains A and B, and papaya peptidase A. J. Protein Chem. 7 119 (1982). 

Papaya peptidase I. Hydrolysis of proteins with broad specificity for peptide bonds, with... 

Recently, Kang and Warner (102) fractionated crude papain into crystalline papain, chymopapain, and papaya peptidase A. Chymopapain constituted the major component of the crude papain, and it proved to be the most thermostable at pH values between 5 and 9. Table VIII shows the activity of the various purified enzymes on native and heat-denatured meat fractions after subtracting blank values. All three enzymes degraded meat fractions, but with somewhat different hydrolytic potencies. Chymopapain showed activity comparable to papain and papaya peptidase A on meat fractions. 

The water-insoluble fraction was more readily digested than the water-soluble fraction. Heat denaturation naturally made meat proteins more readily digested by these enzymes, and the effect of denaturation was more significant in the water-soluble fraction than the other fraction. As expected, hydrolysis of the native connective tissue by these enzymes as indicated by increased hydroxyproline was extremely low. Connective tissue after heat denaturation was readily hydrolyzed. Papaya peptidase A showed about a fivefold increase while papain and chymopapain increased their hydrolyses seven- to tenfold. 

This enzyme [EC 3.4.22.6], also known as papaya proteinase II, is a member of the peptidase family Cl. It is the major endopeptidase of papaya (Carica papaya) latex. It has a specificity similar to that of papain. In addition, there are a number of chromatographic forms of the enzyme. 

This enzyme [EC 3.4.22.25] catalyzes the hydrolysis of peptide bonds with a preference for Gly-Xaa in proteins and small molecule substrates. The enzyme, a member of the peptidase family Cl, is isolated from the papaya plant, Carica papaya. It is not inhibited by chicken cys-tatin, unlike most other homologs of papain. 

In 1988, Looze et al. published a series of articles on the cysteine proteinases from papaya latex. In the first article, they described an alternative way to purify chymopapain and papaya proteinase Q to homogeneity [32], In the following articles the primary structures of chymopapain [33] and papaya proteinase 12 [34] were described (Fig. 1). The primary structure of chymopapain determined by Watson et al. [35] is in perfect agreement with the results of Dubois et al. Jacquet et al. described the proteolytic specificities of chymopapain and papaya proteinase 12 [36]. The polypeptide chain of caricain contains 216 amino acid residues (Mr 23283). The molecule shares 148 identical amino acid residues (68.5%) with papain, 141 with chymopapain (65.2%), and 175 with glycyl endo-peptidase (81.0%). The Ai%,280nm is 18.3 [20]. The three-dimensional structure of caricain has been determined by x-ray diffraction analysis [37,38]. 

Papain, EC 3.4.22.2, the archetype of cysteine peptidases. It was isolated from the latex of the tropical papaya fruit (Carica papaya). Papain is a single-chain protein (212 aa 23 kDa) containing three disulfide bonds and a known three-dimensional structure with 1.65 A resolution The catalytic amino acid residues have been identified as Cys, His and Asn, whereas Gln helps to stabilize the oxyanion hole. Papain has a fairly broad specificity [J. R. Kimmel, E. L. Smith, J. Biol. Chem. 1954, 207, 515 A. C. Storer, R. Menard, Methods Enzymol. 1994, 244, 486]. 

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