Definition. 1 enzyme unit, U, is defined as the quantity of enzyme able to reduce 1 μ;mol NADP+/min at 25°C in 0.02 M triethanolamine-HCl buffer, pH 8.
Aspartate-β-Semialdehyde Dehydrogenase from Escherichia coli
Purification and General Properties
Article first published online: 3 MAR 2005
European Journal of Biochemistry
Volume 104, Issue 1, pages 53–58, February 1980
How to Cite
BIELLMANN, J.-F., EID, P., HIRTH, C. and JÖRNVALL, H. (1980), Aspartate-β-Semialdehyde Dehydrogenase from Escherichia coli. European Journal of Biochemistry, 104: 53–58. doi: 10.1111/j.1432-1033.1980.tb04398.x
- Issue published online: 3 MAR 2005
- Article first published online: 3 MAR 2005
- (Received March 30, 1979)
Aspartate-β-semialdehyde dehydrogenase, from an Escherichia coli mutant derepressed for the biosynthesis of l-lysine, has been purified to homogeneity. Its isoelectric point is pH 4.3. This enzyme has a molecular weight of 77000 and is composed of two identical or highly similar subunits of molecular weight 38000 ± 2000.
Their N-terminal amino-acid sequence is Met-Lys-Asx-Val-Gly-. Three cysteine residues per subunit were detected: two are reactive in the native enzyme and one is partially protected by the substrate. Formation of an acyl-enzyme intermediate was also detected. Correlation of the 1H nuclear magnetic resonance spectrum of [4-2H]NADPH produced from [4-2H]NADP+ indicated that aspartate β-semialdehyde dehydrogenase transfers the pro-S hydrogen from NADPH (class B dehydrogenase). A short comparison with the corresponding yeast enzyme is given.