Isolation and sequence of the pyridoxal 5'-phosphate active-site peptide from Rhodospirillum rubrum ribulose-1,5-bisphosphate carboxylase/oxygenase.
Ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodospirillum rubrum was modified with pyridoxal 5'-phosphate and then reduced with sodium borohydride. Both carboxylase and oxygenase activities were lost when one molecule of pyridoxal 5'-phosphate was bound per enzyme dimer. Peptide maps of modified enzyme showed one N6-(phosphopyridoxal)lysine-containing peptide. This peptide was isolated by gel filtration and cation-exchange chromatography and its sequence determined as Ala-Leu-Gly-Arg-Pro-Glu-Val-Asp-(PLP-Lys)-Gly-Thr-Leu-Val-Ile-Lys. Since activation of the enzyme with Mg2+/CO2 enhances pyridoxal 5'-phosphate modification and subsequent inactivation and the substrate ribulose bisphosphate protects against modification, the modified lysyl group is most certainly at the catalytic site and not at the activation site of the enzyme.
D000595:Amino Acid Sequence; D001665:Binding Sites; D002262:Carboxy-Lyases; D010446:Peptide Fragments / Q000032:analysis; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000201:enzymology*; D012273:Ribulose-Bisphosphate Carboxylase
D010446:Peptide Fragments; D011732:Pyridoxal Phosphate; D002262:Carboxy-Lyases; D012273:Ribulose-Bisphosphate Carboxylase