De terminati on of Acidic Dissociation Constants of ۵´-IMPand ۵´-UMP in Water using DFT Methods

  • سال انتشار: 1391
  • محل انتشار: پانزدهمین سمینار شیمی فیزیک ایران
  • کد COI اختصاصی: ISPTC15_0376
  • زبان مقاله: انگلیسی
  • تعداد مشاهده: 157
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نویسندگان

n M otaghedia

Dep artment of Physical chemist r University of Payam Noor, Mazandaran, I ran.

f Kianib

Department of chemistry, Islamic Azad University, Ayatollah Amoli Branch, A mol, Iran.

m Tajbakhs hc

Department of organic Che mistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran

f Ashrafia

De partment of c hemistry, Islam ic Azad University, Arak B ranch, Arak, Iran.

a Bahadorid

چکیده

Deriv atives of orthophosphoric acid, main ly as esters and anhydri des, are wid ely distributed in living systems. Th ey are part of the so-called phosph ate-sugar backbone of D NA and RN A; in the f orm of nucleotides th ey occur as coenzym es and intermediates [۱]. Inosine-۵'-mono phosphate ( IMP) is a nucleotide i mportant mo nophosphate in metabo lism. Uridine-۵'-mono phosphate ( UMP) is a nucleotide th at is used as a monom er in RNA. It is formed from Orotid ine-۵'-mon phosphate in a dec arboxylation reaction catalyzed by the enzyme orotidylate decarb oxylase [۲]. The acid-base behavio r of nucleot ides, nucleo sides, base s, and polyn ucleotides is essential to deduce the speciation and the possible conformational changes with p H in soluti on [۳]. On the other han d, during t he last two decades ther e has been much intere st in develop ing a metho dology ena bling theoretical prediction of pKa v alues, employing variou s quantum theoretical techniques. Kinds of polarizable continuum m odels have been applied to calculate free energy differenc es for cations, neutral compounds and their a nions. On the basis of solvation fre e energies, the pKa values were obtained for the compoun ds in question by using thermody namic equations; invo lving the combined e xperimental and calculated data [۴]. This paper deals with the influence of fact ors such as the SCRF model applied, choice of a particula r thermodynmic equations, atomic radii used to build a cavity in the solvent (water ), optimization of geom etry in water, inclusio n of electro n correlation , and the di mension of t he basis set on the solvation free en ergies and on the calculated pKa values. In this study, pKa values of IMP and UM P were determined in aqueous solution by ab initio method and tempe rature ۲۵°C.

کلیدواژه ها

Dissociation constant, IMP, U MP, DFT m ethod, solvation free en ergy

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