Inactivation of rat brain acetylcholinesterase by pyridoxal 5'-phosphate.
Effects of pyridoxal 5'-phosphate on the activity of crude and purified acetylcholinesterase from cerebral hemispheres of adult rat brain were examined. Acetylcholinesterase was completely inactivated by incubation with 0.5 mM pyridoxal 5'-phosphate. The enzyme activity remained unaltered in the presence of analogs of pyridoxal 5'-phosphate, pyridoxal, pyridoxamine and pyridoxamine 5'-phosphate. The inhibition of acetylcholinesterase activity by pyridoxal 5'-phosphate appeared to be of a noncompetitive nature, as determined by Lineweaver-Burk analysis. The inhibitory effect of pyridoxal 5'-phosphate on acetylcholinesterase appeared to be a general one, as the activity of the enzyme from the brains of immature chick and egg-laying hen, and from different tissues of the adult male rats, exhibited a similar pattern in the presence of the inhibitor. The inhibitory effects of pyridoxal 5'-phosphate could be reversed upon exhaustive dialysis of the pyridoxal 5'-phosphate-treated acetylcholinesterase preparations. We propose that the effects of pyridoxal 5'-phosphate are due to its interaction with acetylcholinesterase, and that it can be employed as a useful tool for studying biochemical aspects of this important brain enzyme.
D000110:Acetylcholinesterase / Q000302:isolation & purification / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D002645:Chickens; D002648:Child; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D004593:Electrophorus; D005260:Female; D006801:Humans; D008297:Male; D009422:Nervous System Diseases / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000494:pharmacology*; D051381:Rats; D014238:Trichloroacetic Acid
D002800:Cholinesterase Inhibitors; D014238:Trichloroacetic Acid; D011732:Pyridoxal Phosphate; D000110:Acetylcholinesterase