BIOM20001 Lecture Notes - Lecture 14: Sigmoid Function, Glycogenolysis, Cytosol
Document Summary
Allosteric regulation: enzymes catalysing committed and usually irreversible steps. Specialisation of organs: we will compare the metabolism of brain, liver, muscle and adipose. Involves a change in shape and activity of an enzyme that results from binding of a regulatory molecule at a site other than the active site. They are irreversible steps = control points e. g. 3 irreversible steps in glycolysis. Some enzymes can be inhibited by a molecule that bears no resemblance to the substrate. Allosteric enzymes have 2 or more binding sites that interact. Inhibitors/activators that bind to regulatory site distinct from the active site. The sigmoidal curve arises from combination of two michaelis-menten curves. Enzyme shifts between two states, one with high activity and one with low activity. The enzyme is not either on or off as it is with competitive inhibition. Same vmax for r and t-states but different km values. The allosteric inhibitor changes km (the affinity of substrate for enzyme)
