Proline biosynthesis in Escherichia coli. Kinetic and mechanistic properties of glutamate semialdehyde dehydrogenase.
The kinetics of the NADP+- and phosphate-dependent oxidation of glutamic acid 5-semialdehyde are consistent with a rapid-equilibrium random order mechanism. The Km for DL-pyrroline-5-carboxylic acid is 2.5 mM, for NADP+ is 0.05 mM and for phosphate is 0.35 mM. The Vmax is approx. 8.0 units per mg protein. The reaction is highly specific for the DL-pyrroline-5-carboxylic acid and NADP+, but a number of divalent anions can substitute for phosphate. NADPH is competitive with respect to all three substrates and an analog of gamma-glutamyl phosphate, 3-(phosphonoacetylamido)-L-alanine, is competitive with respect to DL-pyrroline-5-carboxylic acid and non-competitive with respect to NADP+ and phosphate, suggesting dead-end complex formation.
D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D050698:Glutamate-5-Semialdehyde Dehydrogenase; D007700:Kinetics; D008433:Mathematics; D009249:NADP; D011392:Proline / Q000096:biosynthesis*; D013379:Substrate Specificity
D009249:NADP; D011392:Proline; D000445:Aldehyde Oxidoreductases; D050698:Glutamate-5-Semialdehyde Dehydrogenase