Structural requirements, synthesis and interaction of secondary nitrosamine inhibitors with acetylcholinesterase from Torpedo fuscomaculata.
A series of secondary diaryl and dialkyl nitrosamines have been synthesised and tested as substrates and/or inhibitors of highly purified acetyl- cholinesterase from Torpedo fuscomaculata. None were found to act as substrate, but many could selectively inhibit the enzyme. Kinetic analysis has shown that all the nitrosamines act as reversible competitive inhibitors with respect to the substrate, acetylthiocholine chloride; with time they act as irreversible covalent inhibitors. Scatchard analysis indicates that aliphatic nitrosamines have a weaker affinity for the enzyme compared to the aromatic and heterocyclic nitrosamines. In all cases the number of binding sites was four. Pseudo first-order kinetics are observed with the rate constant being proportional to the concentration of the nitrosamine and the order of reaction being equal to one.
Mmutle
T B
TB
Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, RSA.
Whiteley
C G
CG
D000110:Acetylcholinesterase / Q000187:drug effects / Q000378:metabolism*; D000122:Acetylthiocholine / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D007700:Kinetics; D015394:Molecular Structure; D009602:Nitrosamines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014101:Torpedo / Q000378:metabolism*
D002800:Cholinesterase Inhibitors; D009602:Nitrosamines; D000122:Acetylthiocholine; D000110:Acetylcholinesterase