Accessibility of hepatocyte protein thiols to monobromobimane
| Autor: | Marianne Weis, Gregory A. Moore, Peter Moldéus, Kajsa Norbeck, Ian C. Cotgreave |
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| Rok vydání: | 1993 |
| Předmět: |
Male
Time Factors Mitochondria Liver Residue (chemistry) chemistry.chemical_compound Bridged Bicyclo Compounds Cytosol Benzoquinones Animals Cysteine Sulfhydryl Compounds Bovine serum albumin Amino Acids Rats Wistar Molecular Biology Cells Cultured Fluorescent Dyes chemistry.chemical_classification HEPES Chromatography biology Chemistry Proteins Serum Albumin Bovine Cell Biology Rats Biochemistry Liver Ethylmaleimide Reagent Thiol Microsome biology.protein Microsomes Liver |
| Zdroj: | Biochimica et biophysica acta. 1176(1-2) |
| ISSN: | 0006-3002 |
| Popis: | The amino-acid residue specificity of monobromobimane (mBBr) and its accessibility to cellular protein cysteine residues were investigated. mBBr reacted selectively with the sulfhydryl group of both the free amino acid cysteine and bovine serum albumin. Incubation of isolated hepatocytes with mBBr resulted in a concentration-dependent formation of protein-bound mBBr fluorescence in the cytosolic, mitochondrial and microsomal fractions, which was not fully saturated with up to 16 mM mBBr. SDS-PAGE resolution of the proteins revealed that the major portion of increased protein-bound mBBr fluorescence that occurred at high mBBr concentrations was due to covalent binding to proteins. A minor portion (10–16% in the microsomal fraction) of protein-bound mBBr fluorescence was removed by SDS-PAGE and is therefore concluded to be due to physical entrapment of fluorescent mBBr reaction products. The accessibility of mBBr, assayed as the degree of depletion of total protein cysteine residues, was similar to N- ethylmaleimide (NEM) in isolated microsomes. By contrast, in the cytosol a markedly lower amount of protein cysteine residues were labelled by mBBr as compared to NEM. In both organelle fractions p- BQ was the most efficient thiol-depleting reagent. It is concluded that mBBr is a suitable reagent for the analysis of the cellular protein thiol status and of its xenobiotic-induced alterations when used at high concentrations; however, it should be considered that, (i) the relative accessibility of mBBr and a particular xenobiotic to cellular protein thiol residues may be different, and (ii) physically entrapped fluorescent reaction products of mBBr should be removed when quantitating protein thiol levels. |
| Databáze: | OpenAIRE |
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