کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10537312 962711 2005 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Kinetic isotope effects of nucleoside hydrolase from Escherichia coli
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
Kinetic isotope effects of nucleoside hydrolase from Escherichia coli
چکیده انگلیسی
rihC is one of a group of three ribonucleoside hydrolases found in Escherichia coli (E. coli). The enzyme catalyzes the hydrolysis of selected nucleosides to ribose and the corresponding base. A family of Vmax/Km kinetic isotope effects using uridine labeled with stable isotopes, such as 2H, 13C, and 15N, were determined by liquid chromatography/mass spectrometry (LC/MS). The kinetic isotope effects were 1.012 ± 0.006, 1.027 ± 0.005, 1.134 ± 0.007, 1.122 ± 0.008, and 1.002 ± 0.004 for [1′-13C], [1-15N], [1′-2H], [2′-2H], and [5′-2H2] uridine, respectively. A transition state based upon a bond-energy bond-order vibrational analysis (BEBOVIB) of the observed kinetic isotope effects is proposed. The main features of this transition state are activation of the heterocyclic base by protonation of/or hydrogen bonding to O2, an extensively broken C-N glycosidic bond, formation of an oxocarbenium ion in the ribose ring, C3′-exo ribose ring conformation, and almost no bond formation to the attacking nucleophile. The proposed transition state for the prokaryotic E. coli nucleoside hydrolase is compared to that of a similar enzyme isolated from Crithidia fasciculata (C. fasciculata).
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics - Volume 1751, Issue 2, 10 August 2005, Pages 140-149
نویسندگان
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