| Figure 1-52 |
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| Catalytic triad | |
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| The catalytic triad of aspartic acid, histidine and serine in (a) subtilisin, a bacterial serine protease, and (b) chymotrypsin, a mammalian serine protease. The two protein structures are quite different, and the elements of the catalytic triad are in different positions in the primary sequence, but the active-site arrangement of the aspartic acid, histidine and serine is similar. |