Caricain chymopapain

Cysteine proteases are so called because of a critical cysteine involved (together with an adjacent histidine) in the catalytic mechanism. Cysteine proteases include papain-related proteases, calpain-related proteases and the caspases. Papain-like cysteine proteases include the plant enzymes actinidin, aleurain, bromelain, caricain, chymopapain, ficin and papain and the lysosomal cathepsins B, C, H, K, L and S. Cathepsin C is multimeric (MW -200,000), but the other papain-related proteases are monomeric with MWs of about 20,000-35,000. While cathepsin C is a dipeptidyl aminopeptidase, the other enzymes are endopeptidases. Cathepsin B is an endopeptidase and a dipeptidyl carboxypeptidase. Cathepsin H is an endopeptidase and an aminopeptidase. In higher animals, cathepsin B generates peptides from antigens for presentation to T cells by the major histocompatibility... 

Jacquct et al. described the proteolytic specificities of chymopapain and papaya proteinase Q [36]. The polypeptide chain of caricain contains 216 amino acid residues (Mr 23283). The molecule shares 148 identical amino acid residues (68,5ft) with papain. 141 with chymopapain (65,2ft), and 175 with glycyl endopeptidase (81.0ft). The Ms,lllOnin is 1U [20]. The three-dimensional structure of caricain has been determined by x-ray diffraction analysis [37,38]-... 

Carica papaya (papaya, paw-paw) (Caricaceae) [recombinant] Carica papain pro-region (107 aa 12 kDa) Caricain [8 nM], Chymopapain [12 nM], Papain [2 nM], Papaya proteinase IV [31 [152]... 

Papain [2nM], chymopapain [12nM], caricain [8nM], papaya proteinase IV [3]... 

To date, the latex of Carica papaya L. is known to contain at least four different proteolytic enzymes, namely, papain (E.C. 3.4.22.2), chymopapain (E.C. 3.4.22.6), caricain or papaya proteinase III or 2 (E.C. 3.4.22.30), and glycyl endopeptidase or papaya proteinase IV (E.C. 3.4.22.25). The importance of the latex of the unripe fruit of the tropical tree Carica papaya L. was first noted by G. C. Roy, who in 1873 published in the Calcutta Medical Journal (see Ref. 1) an article entitled The solvent action of papaya juice on the nitrogenous articles of food. The name papain was used for the first time by Wurtz and Bouchet [2] to describe partially purified cysteine proteinases from the papaya latex. They wrote, nous designerons ce ferment sous le nom de papa ine." In 1880, Wurtz postulated that papain acts in fibrin digestion by becoming bound to the fibrin [3]. This is remarkable in that Emil Fisher first described the specific association of enzyme with substrate in 1898. Since that time, many names have been used for commercial latex products, e.g., papayotin, papaoid, etc. 

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]. 

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]. 

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