Cyanobacterial glutamate 1-semialdehyde aminotransferase: requirement for pyridoxamine phosphate

Glutamate 1-semialdehyde aminotransferase has been separated from metabolically related activities by gel filtration and affinity chromatography. The enzyme was inhibited by gabaculin, 4-amino 5-fluoropentanoic acid and pyridoxal 5-phosphate and stimulated by pyridoxamine 5-phosphate. The activity of enzyme recovered by elution after electrophoresis in non-denaturing polyacrylamide gels was wholly dependent on pyridoxamine 5-phosphate. A mechanism for the enzyme-catalysed reaction based on these observations is discussed.Abbreviations AFPA 4-amino 5-fluoropentanoic acid - ALA -aminolaevulinic acid - DTT dithiothreitol - GSA glutamate 1-semialdehyde - PAL-P pyridoxal 5-phosphate - PAM-P pyridoxamine 5-phosphate - PCC Paris Culture Collection