CHEM 153C Study Guide - Final Guide: Menton, Isozyme, Dephosphorylation
23 Jun 2016
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Document Summary
Control of enzyme amount (gs and lac operon) Control of enzyme activity (gs and pfk; palmitate inhibition of acetyl-coa. Control of substrate availability (fatty acid oxidation and g6p"tase) Specific: response to availability of pathway"s substrate (catabolic pathways) or product (anabolic pathways) e. g. palmitate inhibition of acetyl-coa carboxylase. Signals mediating regulation: availability of regulatory ligands. Control of enzyme amount (genetic regulation: constitutive enzymes: e. g. glycolytic enzymes and gluconeogenic enzymes, repressible enzymes: e. g. ten enzymes of histidine biosynthesis. Usually affects one or a few enzymes in a pathway: regulatory enzymes. Enzyme catalyzing committed, rate-limiting step (often first step) Thermodynamically highly favorable reaction: outcomes of regulation. Modulation of metabolic flux (e. g. pfk: irreversible covalent modification, protein modification (phosphorylation/dephosphorylation) Positive effector (of number of active enzyme molecules. 2 regulatory structures: t and r form (inactive) Multiple substrate catabolic pathways: modulation of metabolic flux (general control): energy charge. Cannot control the gene expression as the enzymes are constitutive.
