1H‐NMR study of the interaction of aminopyrine with purified rat liver microsomal cytochrome P‐450

Abstract
Longitudinal relaxation (T 1) measurements for all lines (N(CH3)2, N(CH3), (C(CH3), phenyl) in the aminopyrine 1H-NMR spectrum were used to study the interaction of aminopyrine with purified microsomal cytochrome P-450 from livers of phenobarbital-treated rats. The paramagnetic contribution to the observed t 1 −1 values was determined from its dependence on aminopyrine concentration. The Solomon-Bloembergen equation was used to calculate between Fe3+ and aminopyrine distances in the enzyme-substrate complex. For all protons these distances are about 8 Å.