Remarkable substrate-inhibitor properties of nicotine enantiomers towards a guinea pig lung aromatic azaheterocycle N-methyltransferase.
The kinetics of nicotine methylation by guinea pig lung homogenates has been investigated. An interesting stereospecificity has been observed for nicotine enantiomers. R-(+)-Nicotine is a substrate Km = 1.42 X 10(-5)M for an SAM-dependent guinea pig lung aromatic azaheterocycle N-methyltransferase, whereas S-(-)-nicotine acts as a competitive inhibitor (Ki = 6.25 X 10(-5)M) of the N-methylation of its antipode.
D000818:Animals; D006168:Guinea Pigs; D007700:Kinetics; D008168:Lung / Q000201:enzymology*; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D009538:Nicotine / Q000494:pharmacology*; D012435:S-Adenosylhomocysteine / Q000494:pharmacology; D013237:Stereoisomerism; D013379:Substrate Specificity; D013997:Time Factors
D009538:Nicotine; D012435:S-Adenosylhomocysteine; D008780:Methyltransferases; C045058:azaheterocycle N-methyltransferase