Calmodulin discriminates between the two enantiomers of the receptor-operated calcium channel blocker SK&F 96365: a study using 1H-NMR and chiral HPLC.
1H nuclear magnetic resonance at 360 MHz shows that SK&F 96365 (1-(beta-[3-(p-methoxyphenyl)-propyloxy]-p-methoxyphenethyl)-1H- imidazole hydrochloride), an antagonist of mammalian receptor-operated calcium channels, interacts with the calcium-binding regulatory protein calmodulin (CaM). This may be inferred by a number of chemical shift changes in the spectrum of the calcium-saturated protein induced by addition of the compound. Moreover, two well-resolved singlets corresponding to the 2-proton of the SK&F 96365 imidazolium moiety are observed in the spectrum over a wide range of protein:compound ratios. Separation of rac SK&F 96365 into its two enantiomers by high-performance liquid chromatography on a cellulose tris (4-methylbenzoate) column enabled us to show that the doubling of this NMR signal in the presence of CaM is due to a propensity of the protein to distinguish between the two optical isomers of the compound.
Reid
D G
DG
Physical Organic Chemistry Department, Smith Kline and French Research Limited, Welwyn, Great Britain.
MacLachlan
L K
LK
Robinson
S P
SP
Camilleri
P
P
Dyke
C A
CA
Thorpe
C J
CJ
D000818:Animals; D002121:Calcium Channel Blockers / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006859:Hydrogen; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D002121:Calcium Channel Blockers; D002147:Calmodulin; D007093:Imidazoles; D006859:Hydrogen; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole