کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1948059 1054673 2010 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Residue 234 is a master switch of the alternative-substrate activity profile of human and rodent theta class glutathione transferase T1-1
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Residue 234 is a master switch of the alternative-substrate activity profile of human and rodent theta class glutathione transferase T1-1
چکیده انگلیسی

BackgroundThe Theta class glutathione transferase GST T1-1 is a ubiquitously occurring detoxication enzyme. The rat and mouse enzymes have high catalytic activities with numerous electrophilic compounds, but the homologous human GST T1-1 has comparatively low activity with the same substrates. A major structural determinant of substrate recognition is the H-site, which binds the electrophile in proximity to the nucleophilic sulfur of the second substrate glutathione. The H-site is formed by several segments of amino acid residues located in separate regions of the primary structure. The C-terminal helix of the protein serves as a lid over the active site, and contributes several residues to the H-site.MethodsSite-directed mutagenesis of the H-site in GST T1-1 was used to create the mouse Arg234Trp for comparison with the human Trp234Arg mutant and the wild-type rat, mouse, and human enzymes. The kinetic properties were investigated with an array of alternative electrophilic substrates to establish substrate selectivity profiles for the different GST T1-1 variants.ResultsThe characteristic activity profile of the rat and mouse enzymes is dependent on Arg in position 234, whereas the human enzyme features Trp. Reciprocal mutations of residue 234 between the rodent and human enzymes transform the substrate-selectivity profiles from one to the other.ConclusionsH-site residue 234 has a key role in governing the activity and substrate selectivity profile of GST T1-1.General significanceThe functional divergence between human and rodent Theta class GST demonstrates that a single point mutation can enable or suppress enzyme activities with different substrates.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochimica et Biophysica Acta (BBA) - General Subjects - Volume 1800, Issue 4, April 2010, Pages 466–473
نویسندگان
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