title: Modification of arginyl residues in ferredoxin-NADP+ reductase from spinach leaves.
abstract: Reaction of spinach leaves ferredoxin-NADP+ reductase (NADPH:ferredoxin oxidoreductase, EC 1.6.7.1) with alpha-dicarbonyl compounds results in a biphasic loss of activity. The rapid phase yields modified enzyme with about 30% of the original activity, but no change in the Km for NADPH. Only partial protection against inactivation is provided by NADP+, NADPH and their analogs, whereas ferredoxin affords complete protection. The reductase inactivated to 30% of original activity shows a loss of about two arginyl residues, whereas only one residue is lost in the NADP+-protected enzymes. The data suggest that the integrity of at least two arginyl residues are requested for maximal activity of ferredoxin-NADP+ reductase: one residue being located near the NADP+-binding site, the other presumably situated in the ferredoxin-binding domain.
mesh_terms: D000447:Aldehydes / Q000494:pharmacology*; D000596:Amino Acids / Q000032:analysis; D001120:Arginine; D002074:Butanones / Q000494:pharmacology*; D003510:Cyclohexanes / Q000494:pharmacology*; D003512:Cyclohexanones / Q000494:pharmacology*; D003931:Diacetyl / Q000494:pharmacology*; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism*; D006037:Glyoxal / Q000031:analogs & derivatives / Q000494:pharmacology*; D007700:Kinetics; D008024:Ligands; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D010944:Plants / Q000201:enzymology*
chemical_list: D000447:Aldehydes; D000596:Amino Acids; D002074:Butanones; D003510:Cyclohexanes; D003512:Cyclohexanones; D008024:Ligands; D006037:Glyoxal; D001120:Arginine; D005287:Ferredoxin-NADP Reductase; D009247:NADH, NADPH Oxidoreductases; D003931:Diacetyl