Abstract
Addition of p-[3H]nitrosophenetole to protein incubations resulted in quantitative binding of radiolabel to protein. Preincubation of protein with N-methylmaleimide to derivatize sulfhydryl groups followed by addition of p-[3H]nitrosophenetole resulted in a 90% decrease in covalent binding. Treatment of the p-[3H]nitrosophenetole protein-bound residue, after extensive solvent washing, with HCl decreased binding by 72% and the corresponding amine, p-phenetidine was detected in the aqueous phase. Inasmuch as incubation of the bound residue with reduced glutathione did not alter protein binding appreciably the involvement of a sulfinanilide S-oxide is suggested. Incubation of p-[3H]phenetidine with microsomal incubation mixtures resulted in NADPH-dependent covalent binding to protein. Treatment of the p-[3H]phenetidine protein-bound residue after extensive solvent washing with HCl decreased binding by 64%. Administration of either p-[3H]phenetidine (500 mg/kg i.p.) or [14C]phenacetin (500 mg/kg i.p.) to mice resulted in covalent binding of radiolabel to protein of liver, lung, kidney, small intestine and blood. Incubation of solvent-washed protein with acid resulted in an approximately 35% decrease in protein binding in lung and blood of both treatment groups.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|