BIOC 3560 Lecture Notes - Lecture 12: Thiol, Reaction Rate, Partial Pressure

• School: University of Guelph
• Department: Biochemistry
• Course: BIOC 3560
• Professor: Mathew Kimber

Document Summary

A: km corresponds to the substrate concentration at which the initial reaction rate (v0) is half the maximal rate. For many enzymes, this corresponds to the substrate concentration at which half the enzyme"s substrate-binding sites are bound to substrate. O2-binding to the heme group of hemoglobin changes its absorption spectrum (it absorbs more light in the blue region) and it appears more red. A: p-hydroxymercuribenzoate (or similar hg-containing compounds) reacts with the sulfhydryl groups of cysteine residues. In atcase specifically, this results in the disassembly of the enzyme into its constituent subunits (catalytic trimers and regulatory dimers). This is based upon the coordination of zn2+ by 4 cys residues within the zinc domain of the regulatory chains. The ability of p-hydroxymercuribenzoate to dissociate the catalytic and regulatory subunits is related to the ability of mercury to bind strongly to the cys residues, displacing the zinc and destabilizing this domain.