title: Essential arginine residues in the active sites of propionyl CoA carboxylase and beta-methylcrotonyl CoA carboxylase.
abstract: At least one arginine residue is essential for substrate binding in or near the active sites of propionyl CoA carboxylase (PCC) and beta-methylcrotonyl CoA carboxylase (beta MCC) in cultured human fibroblasts. This conclusion is based on studies of enzyme inhibition by phenylglyoxal, a reagent which specifically modifies arginine residues. Human fibroblast PCC both in extracts and in a 20-fold purified preparation was nearly completely protected from phenylglyoxal inhibition following incubation with propionyl CoA or ATP. It appears that a phosphate group from either ATP or the CoA moiety of propionyl CoA reacts with the essential arginine residue(s). beta MCC which was similarly inhibited by phenylglyoxal was protected by beta-methylcrotonyl CoA and ATP. Thus phenylglyoxal may be used to label specific arginine residues within the active sites of previously sequenced carboxylases.
mesh_terms: D000214:Acyl Coenzyme A; D001120:Arginine; D001665:Binding Sites; D002245:Carbon Dioxide; D003437:Crotonates; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D008025:Ligases / Q000378:metabolism*; D010658:Phenylglyoxal / Q000494:pharmacology; D011422:Propionates; D012867:Skin
chemical_list: D000214:Acyl Coenzyme A; D003437:Crotonates; D011422:Propionates; D002245:Carbon Dioxide; D001120:Arginine; D008025:Ligases; D010658:Phenylglyoxal