Binding Position of Phenylbutazone with Bovine Serum Albumin Determined by Measuring Nuclear Magnetic Resonance Relaxation Time

概要

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The binding of phenylbutazone (PB) to bovine serum albumin (BSA) was condidered to be predominantly due to hydrophobic interaction based on the thermodynamic parameters obtained by an equilibrium dialysis method. Little variation of proton nuclear magnetic resonanc (^1H-NMR) chemical shift of PB was found with change in the concentration of PB 0.5-5 mM) or upon the addition of BSA (7.25×10^<-5> M). The NMR spectrum of PB in 0.1 M phosphate buffer solution at pH 7 showed that PB existed as a mesomeric anion. The spin-lattice relaxation time (T_1) of PB was almost concentration-independent, but decreased in the presence of BSA to 36-38% for the phenyl group and 48-100% for the butyl group. The spin-spin relaxation time (T_2) of PB was also almost independent of concentration, but was remarkably decreased in the presence of BSA to ca. 2.5% for the phenyl group and ca. 6-9% for the butyl group. The ratios of the spin-relaxation rate (1/T_2) of the free PB to that of the bound PB were ca. 5000-11000 for the butyl group and ca. 23000 for the phenyl group. The binding of PB to BSA was considered to involve primarily the phenyl group.
公益社団法人日本薬学会の論文
1989-12-25