کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1927418 | 1536511 | 2007 | 8 صفحه PDF | دانلود رایگان |
Phenol sulfotransferases (SULTs), which normally bind 3′-phosphoadenosine-5′-phosphosulfate as the donor substrate, are inhibited by CoA and its thioesters. Here, we report that inhibition of bovine SULT1A1 by CoA is time-dependent at neutral pH under non-reducing conditions. The rates of inactivation by CoA indicate an initial reversible SULT:CoA complex with a dissociation constant of 5.7 μM and an inactivation rate constant of 0.07 min−1. Titrations with CoA and prolonged incubations reveal that inactivation of the dimeric enzyme is stoichiometric, consistent with the observation of complete conversion of the protein to a slightly decreased electrophoretic mobility. Both activity and normal electrophoretic migration are restored by 2-mercaptoethanol. Mutagenesis demonstrated that Cys168 is the site of CoA adduction, and a consistent model was constructed that reveals a new SULT molecular dynamic. Cysteine reaction kinetics with Ellman’s reagent revealed a PAPS-induced structural change consistent with the model that accounts for binding of CoA.
Journal: Archives of Biochemistry and Biophysics - Volume 457, Issue 2, 15 January 2007, Pages 197–204