BIOC12H3 Lecture Notes - Lecture 10: Thiol, Cystine, Nicotinamide
23 Sep 2016
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2. coenzymes and vitamins activation of some pancreatic zymogens: what is a zymogen? a. inactive enzyme precursor, enzymes made in pancreas and then they get moved and cut into active form. 3. trypsin a. cleaves various zymogens to activate them. 4. feedback regulation not shown, but very much present comparison of polypeptide backbones (chymotrypsin / trypsin / elastase) Becomes a very strong nucleophile that will attack the peptide bond: highly stable because aspartate-102 stabilizes histidine c. i. Histidine promotes attack on serine: serine potentially present in active site d. i. Normally not sufficiently acidic to undergo deprotonation d. i. 1. a. Mechanism to do this is covalent and acid-base catalysis. Includes covalent catalysis: by a nucleophilic oxygen, general acid-base catalysis, donation of a proton to form a leaving group, binding of a peptide (substrate) causes a small conformational change in chymotrypsin, which sterically compresses asp-102 and his-57.
