The enantioselective participation of (S)- and (R)-diaminovaleric acids in the formation of delta-aminolevulinic acid in cyanobacteria.
Although it is recognized that 4,5-diaminovaleric acid, formed from glutamate 1-semialdehyde, functions as the intermediate in the last step of delta-aminolevulinic acid formation from glutamate, the enantioselectivity of the participating glutamate 1-semialdehyde aminotransferase for 4,5-diaminovaleric acid has remained unknown. In the present work the involvement of (S)- and (R)-4,5-diaminovaleric acids, newly available by organic synthesis, was investigated, using glutamate 1-semialdehyde aminotransferase from Synechococcus. The preferred enantiomer was (S)-4,5-diaminovalerate. In experiments on the transformation of (S)-4,5-diaminovalerate to delta-aminolevulinate it was found that glutamate 1-semialdehyde aminotransferase was unusual among aminotransferases in that the common amino acceptors pyruvate, oxaloacetate, alpha-ketoglutarate were inactive, while 4,5-dioxovaleric acid could be utilized as a sluggish amino acceptor in place of glutamate 1-semialdehyde. In conclusion, glutamate 1-semialdehyde aminotransferase is highly but not absolutely enantioselective for (S)-4,5-diaminovaleric acid, and 4,5-dioxovaleric acid can function as amino acceptor not because of a physiological role in the C5 pathway of delta-aminolevulinic acid formation, but because of its structural resemblance to glutamate 1-semialdehyde.
Friedmann
H C
HC
Department of Biochemistry and Molecular Biology, University of Chicago, IL 60637.
Duban
M E
ME
Valasinas
A
A
Frydman
B
B
D000599:Amino Acids, Diamino / Q000378:metabolism*; D000622:Aminolevulinic Acid / Q000378:metabolism*; D000458:Cyanobacteria / Q000201:enzymology / Q000378:metabolism*; D019751:Intramolecular Transferases; D007535:Isomerases / Q000187:drug effects / Q000378:metabolism*; D007656:Ketoglutaric Acids / Q000494:pharmacology; D010071:Oxaloacetates / Q000494:pharmacology; D011773:Pyruvates / Q000494:pharmacology; D019289:Pyruvic Acid; D013237:Stereoisomerism
D000599:Amino Acids, Diamino; D007656:Ketoglutaric Acids; D010071:Oxaloacetates; D011773:Pyruvates; D019289:Pyruvic Acid; D000622:Aminolevulinic Acid; C074874:4,5-diaminopentanoic acid; D007535:Isomerases; D019751:Intramolecular Transferases; C061049:glutamate-1-semialdehyde 2,1-aminomutase