[Effects of pyridoxal-phosphate and its 4'- and 5'-substituted analogs on macromolecular structure of Escherichia coli glutamate decarboxylase].
Interactions of pyridoxal phosphate and its analogs (at pH 6.0) with dimeric glutamate apodecarboxylase (E. coli) were examined by spectrophotometric and CD-titration and by gel electrophoresis. It was shown that 5 equivalents of pyridoxal-phosphate fully restore the catalytic activity and optical properties of the enzyme, whereas 3 equivalents of the coenzyme suffice for reconstitution of the hexameric structure. Similar amounts of the 2 nor PLP adn 5'-methtyl PLP restore the hexameric macromolecule. 15 equivalents of pyridoxine phosphate or 54 -- of pyridoxamine phosphate are required for complete saturation of the apoenzymes binding sites and concomitant reconstitution of the hexameric structure. 5'-deoxy-5'-carboxymethyl pyridoxal, 5'-deoxy-5'-phosphonomethyl pyridoxal and cis-5'-deoxy-5'-phosphonomethylen pyridoxal were merely bound to the dimeric apoenzyme, but failed to restore the enzyme's quaternary structure. Pyridoxal, trans-5'-deoxy-5'-posphonomethylen pyridoxal and pyridoxine analogs substituted in position 5' with carboxyl or phosphonyl group did not interact with the apodecarboxylase.
D002262:Carboxy-Lyases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D005968:Glutamate Decarboxylase / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013053:Spectrophotometry; D013329:Structure-Activity Relationship
D046911:Macromolecular Substances; D011732:Pyridoxal Phosphate; D002262:Carboxy-Lyases; D005968:Glutamate Decarboxylase
Vliianie pirodoksal'fosfata i ego 4'- i 5'-zameshchennykh analogov na makromolekuliarnuiu strukturu glutamatdekarboksilazy Escherichia coli.