Differences in the occurrence of glutathione transferase isoenzymes in rat lung and liver |
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Authors: | Iain GC Robertson Helgi Jensson Claes Guthenberg Mohammad Kalim Tahir Bengt Jernström Bengt Mannervik |
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Institution: | 1. Department of Toxicology, Karolinska Institutet, Box 60400, S-104 01 Stockholm, Sweden;2. Department of Biochemistry, Arrhenius Laboratory, University of Stockholm, S-106 91 Stockholm, Sweden |
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Abstract: | Cytosolic GSH transferases have been purified from rat lung by affinity chromatography followed by chromatofocusing. On the criteria of order of elution, substrate specificity, apparent subunit Mr, sensitivity to inhibitors, and reaction with antibodies, transferase subunits equivalent to subunits 2, 3, and 4, in the binary combinations occurring in liver, were identified. However, subunit 1 (and therefore transferases 1-1 and 1-2) was not detected. The most conspicuous difference is the presence in lung of a new form, eluting at pH 8.7, which is not detected in rat liver. This isoenzyme (transferase "pH 8.7") is characterized by its low apparent subunit Mr and high efficiency in the conjugation of glutathione with anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide, considered the ultimate carcinogen of benzo(a)-pyrene. |
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Keywords: | GSH glutathione CDNB 1-chloro-2 4-dinitrobenzene BPDE DTE dithioerythritol SOS sodium dodecylsulfate |
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