The effects of acetone on liver, kidney, and lung monooxygenases were studied using hamsters administered 8% acetone in drinking water. Binding of aniline to liver microsomes induced a type II difference spectrum, and the spectral binding was enhanced in hamsters pretreated with acetone. Administration of acetone caused significant increases of cytochrome P-450 and cytochrome b5 contents in liver microsomes. The increases of the hemeproteins were associated with induction of monooxygenase activities toward test substrates, aniline, N-nitrosodimethylamine, benzphetamine, benzo(a)pyrene, and 7-ethoxycoumarin. In the kidneys, acetone administration increased microsomal contents of the hemeprotein and monooxygenase activities toward aniline. N-nitrosodimethylamine, and 7-ethoxycoumarin, but not benzphetamine or benzo(a)pyrene. In the lungs, acetone pretreatment increased aniline hydroxylase activity without affecting the levels of N-nitrosodimethylamine demethylase, cytochromes P-450 and b5. In marked contrast to the inductive effects in the liver, acetone administration markedly decreased lung microsomal benzo(a)pyrene hydroxylase and 7-ethoxycoumarin O-deethylase activities. Gel electrophoresis of liver and kidney microsomes from control and acetone-treated hamsters revealed that acetone treatment enhanced the intensity of a protein band(s) in the cytochrome P-450 molecular weight region. Immunoblotting of the microsomal proteins showed that the protein band induced by acetone in hamster liver, kidney and lung was cross-reactive with antibody raised against ethanol-inducible human liver cytochrome P-450. These results demonstrate that acetone has the ability to uniformly induce a specific form of cytochrome P-450, designated as IIE1, and to cause differential changes of monooxygenase activities in the hamster tissues.(ABSTRACT TRUNCATED AT 250 WORDS)
Bovine rhodopsin was subjected to reductive methylation in the dark using formaldehyde and high specific activity sodium borotritide. After purification by gel filtration and affinity chromatography on Concanavalin A-Sepharose, the product retained its immunoreactive properties. [3H]-Reductively methylated rhodopsin (specific activity, 32 Ci/mmole) was suitable for use in radioimmunoassays for rhodopsin, having many advantages over radioiodinated rhodopsin for this purpose. The site of the reductive methylation was shown to be the non-active site lysines with the production of tritiated N-epsilon-dimethyllysine and tritiated N-epsilon-methyllysine in a molar ratio of about 1.3:1, respectively. In terms of stability, ease of preparation, and specificity, tritiated, reductively methylated rhodopsin presents itself as a preferable ligand to radioiodinated rhodopsin in many applications, such as the radioimmunoassay.
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