BCH 3125 Lecture Notes - Lecture 3: Oxyanion Hole, Enzyme Kinetics, Catalytic Triad

• School: University of Ottawa
• Department: Biochemistry
• Course: BCH 3125
• Professor: Corrie Da Costa

Document Summary

The li(cid:374)k (cid:271)et(cid:449)ee(cid:374) (cid:858)rate e(cid:374)ha(cid:374)(cid:272)e(cid:373)e(cid:374)t(cid:859) a(cid:374)d the de(cid:272)rease i(cid:374) a(cid:272)ti(cid:448)atio(cid:374) e(cid:374)erg(cid:455) defi(cid:374)es how much energy is provided through enzyme-substrate interactions leading to catalysis. We can look at structure to identify the interactions between the enzyme and substrate, but we need to quantify how much energy is derived from each interaction. The enzyme binds the substrate to form the es complex. In the es complex, the nucleophilic oh of ser(cid:1005)95 atta(cid:272)k the peptide (cid:271)o(cid:374)d leadi(cid:374)g to the for(cid:373)atio(cid:374) of the (cid:858)tra(cid:374)sitio(cid:374) state(cid:859) Specifically, we hypothesize that a serine protease stabilizes the tetrahedral oxyanion transition state by: the formation of a covalent bond with the peptide bond carbon atom, the formation of hydrogen bonds with the oxyanion. The enzyme increases the reaction rate by 1010-fold (by 57. 1 kj/mol) Approach: individual residues in both the catalytic cycle triad and the oxyanion hole are changed using molecular biology.