Aspartate semialdehyde dehydrogenase

Orthophosphate as substrate or product, ACETATE KINASE (PYROPHOSPHATE) ACETYL-CoA CARBOXYLASE ACID PHOSPHATASE ACTOMYOSIN ATPase ACYL PHOSPHATASE ASPARTATE-SEMIALDEHYDE DEHYDROGENASE ATPases... 

Zhang, W.W. Jiang, W.H. Zhao, G.P. Yang, Y.L. Chiao, J.S. Expression in Escherichia coli, purification and kinetic analysis of the aspartokinase and aspartate semialdehyde dehydrogenase from the rifamycin SV-producing Amycolatopsis mediterranei U32. Appl. Microbiol. Biotechnol., 54, 52-58 (2000)... 

The fluoromethylene and difluoromethylene linkages have also been incorporated into an aspartyl phosphate, providing the first synthetic inhibitors of aspartate semialdehyde dehydrogenase [136] as well as lysophosphatidic acid analogues, which increased the half-lives of analogues in cell culture [137],... 

Aspartyl Phosphate + NADPH + H+ <=> Aspartic Semialdehyde + NADP+ + Pi (catalyzed by Aspartate Semialdehyde Dehydrogenase)... 

The next two reactions in the pathway are catalyzed by aspartate semialdehyde dehydrogenase and homoserine dehydrogenase, respectively (Fig. 2). Both enzymes were initially detected in extracts of pea seedlings (Sasa-oka and Inagaki, 1960 Sasaoka, 1961) and subsequently characterized as B stereospecific with respect to hydride transfer from the dihydropyridine ring of NADPH (Davies el al., 1972). Aspartate semialdehyde dehydrogenase has also been detected in extracts of maize shoots, roots, developing kernels,... 

Aspartate kinase, aspartate semialdehyde dehydrogenase 2 homoserine dehydrogenase 3 homoserine kinase, threonine synthase 4 aspartate 4-decarboxylase... 

So, the biosynthesis of methionine (Met, M), the first of the essential amino adds to be considered (Scheme 12.13), begins by the conversion of aspartate (Asp, D) to aspartate semialdehyde in the same way glutamate (Glu, E) was converted to glutamate semialdehyde (vide supra. Scheme 12.6). Phosphorylation on the terminal carboxylate of aspartate (Asp, D) by ATP in the presence of aspartate kinase (EC 2.7.2.4) and subsequent reduction of the aspart-4 yl phosphate by NADPH in the presence of aspartate semialdehyde dehydrogenase (EC 1.2.1.11) yields the aspartate semialdehyde. The aspartate semialdehyde is further reduced to homoserine (homoserine oxoreductase, EC 1.1.1.3) and the latter is succinylated by succinyl-CoA with the liberation of coenzyme A (CoA-SH) in the presence of homoserine O-succinyl-transferase (EC 2.3.1.46). Then, reaction with cysteine (Cys, C) in the presence of cystathionine y-synthase (EC 2.5.1.48) produces cystathionine and succinate. In the presence of the pyridoxal phosphate protein cystathionine P-lyase (EC 4.4.1.8), both ammonia and pyruvate are lost from cystathionine and homocysteine is produced. Finally, methylation on sulfur to generate methionine (Met, M) occurs by the donation of the methyl from 5-methyltetrahydrofolate in the presence of methonine synthase (EC 2.1.1.13). 

Aspartyl phosphate is reduced to aspartic-/3-semialdehyde (ASA) by aspartic semialdehyde dehydrogenase. The reaction resembles that catalyzed by triose phosphate dehydrogenase, but specifically requires TPN (III). The equilibrium constant is about 3 X 10 , so that at neutral... 

Boy E, Patte JC (1972) Mirltivalent repression of aspartic semialdehyde dehydrogenase in Escherichia coli K-12. J Bacteriol 112 84—92... 

Figure 19.2 Keto-add pathways for the production of n-butanol, isobutanol, and related compounds. Enzyme abbreviations Pyk, pyruvate kinase Ppc, phosphoenolpyruvate carboxylase AspC, aspartate aminotransferase ThrA, apartate kinase/homoserine dehydrogenase asd, aspartate semialdehyde dehydrogenase ThrB, homoserine kinase ThrC, threonine synthase LeuA, 2-isopropylmalate synthase LeuCD, 2-isopropylmalate hydrolyase/3-isopropylmalate...

The genes of the enzymes responsible for the biosynthesis of lysine in Corynebacterium have been cloned, and their nucleotide sequences are known. These genes include aspartokinase, aspartate semialdehyde dehydrogenase, dihydrodipicolinate... 

The reactions catalyzed by aspartokinase (1) and aspartate semialdehyde dehydrogenase (2) are utilized for the synthesis of all pathway products, including threonine. Regulation of aspartokinase activity is, therefore, considered to be of central importance in the overall control of the pathway. Two classes of differentially regulated isozymes of aspartokinase have been isolated from plants. One class is comprised of enzymes subject to feedback inhibition by threonine the other encompasses those inhibited by lysine, or by lysine and 5 -adenosylmethionine. Examples of each class have been isolated from several... 

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