CHM372H5 Lecture 4: The Enzyme Machine
Document Summary
Interactions: enzyme-ligand and enzyme-protein: multimerization, role of dynamics in catalysis, half-of-sites reactivity. Inhibition by substrate: enzyme-ligand & enzyme-protein interactions, conformational selection, enzyme-ligand: lock and key model gives specificity, enzyme-protein interactions: action of receptor - induced fit model. Sampled in a biased way: conformation selection: pre-sampling of states that it needs to accomplish (strong bias, crystallography tends to only give the lowest state, multimerization, most proteins don"t exist as monomers, most common is a dimer. Why: cooperativity - most obvious but not most common, possibility is created, gain of function, dimer implies 2 binding sites, 1 participates in pushing the chemistry -> gain of function, dimeric enzyme - 1 binding siate. Because cell is very dense, it is more economic. Know by the end of the talk: half-of-sites reactivity, 1 subunit of dimer only reacts, dimer is not cooperative and never binds 2 substrates. > conformational selection: heme cofactor -> reaction of arachidonic acid to form prostaglandin, cox-2 inhibitor - aspirin.
