title: Succinic semialdehyde dehydrogenase. Reactivity of lysyl residues.
abstract: The enzyme succinic semialdehyde dehydrogenase from pig brain has been 2000-fold purified by a combination of DEAE-cellulose, hydroxyapatite, and AMP-Sepharose chromatography. This preparation has a molecular weight of 160,000 and a specific activity of 5.3 mumol/min.mg at 25 degrees C. The inhibition of succinic semialdehyde dehydrogenase by carbonyl compounds, i.e. P-pyridoxal and o-phthalaldehyde was investigated in detail. The enzyme is reversible, inhibited by preincubation with P-pyridoxal (mixing molar ratio, 300:1) at either 25 degrees or 37 degrees C. Reduction with NaBH1 results in the incorporation of approximately 4 mol of P-pyridoxyl residues/mol of enzyme. NAD+ protects the enzyme against inactivation by P-pyridoxal, whereas the substrate succinic semialdehyde failed to prevent the reaction of P-pyridoxal with lysine residues of the protein. The binding of approximately 10 mol of o-phthalaldehyde/mol of enzyme results in irreversible loss of catalytic activity. The reaction is fast and easily monitored by absorption and fluorescence spectroscopy.
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology*; D007700:Kinetics; D008239:Lysine; D008970:Molecular Weight; D009243:NAD / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D013386:Succinates; D013552:Swine; D009764:o-Phthalaldehyde / Q000494:pharmacology
chemical_list: D013386:Succinates; D009243:NAD; D011732:Pyridoxal Phosphate; D009764:o-Phthalaldehyde; D000445:Aldehyde Oxidoreductases; D008239:Lysine