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Enzymatic Hydrolysis and Group Transfer Reactions 83
animals for the breakdown of the protein content of food and are produced in
large quantities in the stomach and pancreas. DiVerent types of peptidases are
produced elsewhere in the body for a large assortment of hydrolytic purposes,
notably their key involvement in the blood coagulation cascade. Other proteases
are produced in a wide range of species, including bacteria, yeasts, and
plants, of which a selection are listed in Table 5.2. Note that there is an active
Table 5.2 Some commercially available proteases.
Name Class Exo/endo SpeciWcity Source pH opt
Bromelain Cys Endo X–X Pineapple 6.0
Carboxypeptidase A Metallo Exo (C) X–C (not Arg, Lys) Bovine pancreas 7–8
Carboxypeptidase B Metallo Exo (C) X–C (Arg/Lys) Pig pancreas 7–9
Carboxypeptidase P Ser Exo (C) X–C Penicillium 4–5
Carboxypeptidase Y Ser Exo (C) X–C Yeast 5.5–6.5
Cathepsin C (dipeptidase) Cys Exo (N) N–Gly/Pro–X Bovine spleen 4–6
Cathepsin D Asp Endo Phe/Leu–X Bovine spleen 3–5
Chymotrypsin A Ser Endo Aro–X Bovine pancreas 7.5–8.5
Clostripain Cys Endo Arg–X Clostridium 7.1–7.6
Elastase Ser Endo Neutral aa–X Porcine pancreas 7.8–8.5
Factor X Ser Endo Arg–X Bovine plasma 8.3
Leucine aminopeptidase Metallo Exo (N) N(not Arg/Lys)–X Porcine kidney 7.5–9
Papain Cys Endo Arg/Lys–X Papaya plant 6–7
Pepsin Asp Endo Hyd–X Porcine stomach 2–4
Proteinase K Ser Endo X–Aro/Hyd Tritirachium album 7.5–12
Renin Asp Endo His–Leu–X Porcine kidney 6.0
Subtilisin Carlsberg Ser Endo Neutral/acidic aa–X Bacillus subtilis 7–8
Thermolysin Metallo Endo X–Hyd B. thermoproteolyticus 7–9
Thrombin Ser Endo Arg–Gly Bovine plasma 7–8
Trypsin Ser Endo Lys/Arg–X Bovine pancreas 8.5–8.8
V8 Protease Ser Endo Asp/Glu–X Staphylococcus aureus 7.8
aa, amino acid; Aro, aromatic amino acid (Phe/Tyr/Trp); C, C-terminal amino acid; Hyd, hydrophobic amino acid
(Leu/Ile/Val/Met); N, N-terminal amino acid; X, any amino acid.