Acetylglutamic-y-semialdehyde

Baich, A. Vogel, H.J. N-Acetyl-y-glutamokinase and N-acetylglutamic y-semialdehyde dehydrogenase repressible enzymes of arginine synthesis in Escherichia coh. Biochem. Biophys. Res. Commun., 7, 491-496 (1962)... 

In the conversion of the /V-acetyl-y-glutamyl phosphate to A-acetylglutamic-y-semialdehyde (fig. 22.2), two processes occur An elimination of a phosphate and a reduction. Which step occurs first Also can you propose a reason for the use of the phosphate group in the first place ... 

A -acetylglutamic y-semialdehyde dehydrogenase [4, 7], acetylornithine 5-transaminase [1, 8, 9], acetylornithinase [1, 10, 11], ornithine trans-carbamylase [12], and argininosuccinase [13] have been partially purified and characterized. A -Acetylglutamate synthetase activity has been exhibited in extracts [14], and this enzyme, which catalyzes the first step of the pathway, has been shown in cell suspension experiments to be subject to feedback inhibition by arginine [15],... 

Also in strain K12, an arginine auxotroph evidently producing a nonfunctional A-acetylglutamic y-semialdehyde dehydrogenase was found to show diminished repressibility of other arginine enzymes. 

Glutamic acid A-Acctylglutamic acid —> A -Acetylglutamic -y-semialdehyde... 

Glutamic acid acetylglutamic acid glutamic-y-semialdehyde —> acetylomithine... 

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