Cysteine proteases 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... 

For soluble and immobilized bromelain, temperature increase is accompanied by a decrease in residual enzyme activity. A more complex form of denaturation occurs with the immobilized enzyme, which may involve a two-phase process. Immobilization offers more resistance to denaturation at the higher temperature of 60°C where the second phase is prolonged by a factor of three [60]. Differential scanning calorimetry experiments showed that bromelain is an exceptional protease among the cysteine proteases, illustrated by the fact that its thermal denaturation is consistent with an irreversible two-state model [61]. Also, the far UV circular dichroism spectrum of bromelain differs from those of papain and chymopapain and therefore represents a third spectral class within the cysteine proteinase family [62],... 

Clan CA is composed of twenty families. Family Cl within clan CA is divided into two subfamilies that consist of CIA (papain subfamily) and CIB (bleomycin hydrolase subfamily) groups. The larger subfamily CIA consists of secreted and lysosomal proteases that include the animal cysteine cathepsin proteases cathepsins B, H, and L as well as the plant proteases papain, chymopapain, and actinidain. 

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