MBB 222 Study Guide - Midterm Guide: Allosteric Regulation, Hemoglobin, Globin

• School: Simon Fraser University
• Department: Molec Biol & Biochem
• Course: MBB 222
• Professor: Adam Barlev

Document Summary

Oxygen is a positive allosteric effector of hemoglobin, meaning that the binding of a single o2 molecule to one globin subunit shifts the conformational equilibrium from the t state toward the r state. This increases o2 affinity in other subunits (see figure. Oxygen binding to hemoglobin represents homotropic allostery because o2 binding affects the binding of other o2 molecules (these ligands are the same). Three other allosteric effectors that modulate o2 affinity of hemoglobin are co2, h+, and. However, these three molecules function as negative allosteric regulators because they shift the conformational equilibrium from the r state toward the t state, reducing hemoglobin s affinity for oxygen. These molecules all mediate heterotropic allostery, which refers to the mechanism whereby allosteric effectors bind to secondary sites in the protein. This in turn affects ligand binding at the primary site (o2 binding site). Understand 3 main methods besides just binding substrates which enzymes use to catalyze reactions: acid-base, metal ion, and covalent.