کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10586916 981409 2012 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Trimeric purine nucleoside phosphorylase: Exploring postulated one-third-of-the-sites binding in the transition state
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Trimeric purine nucleoside phosphorylase: Exploring postulated one-third-of-the-sites binding in the transition state
چکیده انگلیسی
Transition-state analogue inhibitors, immucillins, were reported to bind to trimeric purine nucleoside phosphorylase (PNP) with the stoichiometry of one molecule per enzyme trimer [Miles, R. W.; Tyler, P. C.; Furneaux, R. H.; Bagdassarian, C. K.; Schramm, V. L. Biochem. 1998, 37, 8615]. In attempts to observe and better understand the nature of this phenomenon we have conducted calorimetric titrations of the recombinant calf PNP complexed with immucillin H. However, by striking contrast to the earlier reports, we have not observed negative cooperativity and we got the stoichiometry of three immucillin molecules per enzyme trimer. Similar results were obtained from fluorimetric titrations, and for other inhibitors bearing features of the transition state. However, we observed apparent cooperativity between enzyme subunits and apparent lower stoichiometry when we used the recombinant enzyme not fully purified from hypoxanthine, which is moped from Escherichia coli cells. Results presented here prove that one-third-of-the-sites binding does not occur for trimeric PNP, and give the highly probable explanation why previous experiments were interpreted in terms of this phenomenon.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Bioorganic & Medicinal Chemistry - Volume 20, Issue 22, 15 November 2012, Pages 6758-6769
نویسندگان
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