Enantioselective N-Acetylation of N-Desisopropylpropranolol by Rat Liver Acetyltransferase

概要

論文の詳細を見る
The enantioselective N-acetylation of N-desisopropylpropranolol (NDP), one of the main metabolites of propranolol (PL), by rat liver acetyltransferase (AT), was investigated. R(+)-NDP or S(-)-NDP was used as a substrate at concentrations ranging from 10 to 200 μM. The cytosol fraction of a rat liver containing 3.93 mg protein/ml served as the source of AT. For 1-amino-3-(1-naphthyloxy)-2-propanol (AcNDP) formation from R(+)-NDP or S(-)-NDP in the presence of infinite AcCoA (250 μM), the K_m value was calculated to be 67.5 or 62.4 μM, and the V_<max> value was 0.462 or 0.205 nmol/min/mg protein. Based on these findings, the enantioselective N-acetylation of NDP was proved, i.e., AcNDP formation from R(+)-NDP was found to take place more easily than that from S(-)-NDP. Furthermore, AcNDP formation from NDP was competitively inhibited by the exogenous arylamine, p-aminobenzoic acid (PABA), which is well-known to be a typical substrate of AT. The presence of enantioselective inhibition for AcNDP formation was thus confirmed based on the K_i values, 440 μM in the case of R(+)-NDP and 250 μM in the case of S(-)-NDP, respectively, i.e. two-fold enantioselective inhibition was demonstrated based on the Ki values in S(-)-enantiomer incomparison with R(+)-enantiomer.
公益社団法人日本薬学会の論文
1998-12-15