Phosphoserine transaminase
IUPAC Nomenclature of a catalyst enzyme
From Wikipedia, the free encyclopedia
Phosphoserine transaminase (EC 2.6.1.52, PSAT, phosphoserine aminotransferase, 3-phosphoserine aminotransferase, hydroxypyruvic phosphate-glutamic transaminase, L-phosphoserine aminotransferase, phosphohydroxypyruvate transaminase, phosphohydroxypyruvic-glutamic transaminase, 3-O-phospho-L-serine:2-oxoglutarate aminotransferase, SerC, PdxC, 3PHP transaminase) is an enzyme with systematic name O-phospho-L-serine:2-oxoglutarate aminotransferase.[1] This enzyme catalyses two reversible chemical reactions. In the first, phosphoserine is converted to phosphohydroxypyruvic acid by transfer of an amino group to α-ketoglutaric acid, giving L-glutamic acid:
This reaction normally proceeds in the direction of formation of phosphoserine, and is part of the pathway to the amino acid, serine, as found in Escherichia coli and sheep.[2][3][4] As with many aminotransferases, the enzyme uses pyridoxal phosphate as a cofactor.[5][6]
Alternatively, 4-(phosphonooxy)-L-threonine is converted to (R)-3-hydroxy-2-oxo-4-phosphonooxybutanoic acid with the same α-ketoglutaric acid / L-glutamic acid exchange:
-L-threonine.svg)
acid
-3-hydroxy-2-oxo-4-phosphonooxybutanoic_acid.svg)
acid
This reaction, when used to give 4-(phosphonooxy)-L-threonine, is part of the biosynthesis of vitamin B6, (pyridoxal 5'-phosphate), and thus the enzyme in E. coli is involved in making its own cofactor.[7][8]
