Twelve binary and eight ternary H-bonded systems between uracil and water=methanol were investigated at the B3LYP and MP2 theoretical levels using 6 31þG(d) basis functions. The binary and ternary systems that contain the hydroxo-uracil tautomer H-bonded with water and methanol were found to be the most stable complexes. The calculated energy barriers of the intermolecular proton exchange showe...

A number of reports have appeared in recent years on the mechanism, i.e. the mode of enzyme and substrate interaction, of anaerobic dehydrogenases. For example, the mechanisms of heart muscle lactate dehydrogenase (1)) yeast alcohol dehydrogenase (2), and ribitol dehydrogenase (3) appear to involve a compulsory sequence of enzyme and substrate interaction leading to one or more kinetically impo...

Reasoning by analogy is an important component of common sense reasoning whose formalization has undergone recent improvements with the logical and algebraic study of the analogical proportion. The starting point of this study considers analogical proportions on a formal context. We introduce analogical complexes, a companion of formal concepts formed by using analogy between four subsets of ob...

Quantitative indication of the process of forming a complex comes from the evaluation of the stability constants which characterize the equilibria corresponding to the successive addition of ligands. A technique involving the use of paper electrophoresis is described for the study of binary complex system in solution. The first and second stability constants of metal(II) – sarcosine complexes w...

A recent technique involving the use of paper electrophoresis is described for the study of equilibria in binary complex systems in solution. The stability constants of the ML and ML2 complex species of some metal ions, namely beryllium(II) and cobalt(II), with hydroxyproline were determined in 0.1 mol L perchloric acid and a temperature of 35 °C. The logarithm stability constants of the ML and...

In this work, we have studied the pH-dependence of the formation of DQCB[8] complexes by surface-enhanced Raman scattering (SERS) spectroscopy. The SERS spectra suggest that at acidic pH CB[8] can form a binary complex with the dication DQ(+2) while at higher pH ternary complexes with the radical cation dimer (DQ(+)˙)(2) and the radical cation-dication dimer (DQ(+)˙DQ(+2)) are formed. The pH-en...

Individual ribosomal proteins S4, S9 and S13 were tested for their ability to interact with tRNA and synthetic polynucleotides. All three proteins bind to immobilized to Sepharose poly(A) and poly(U), while S4 and S13 form stoichiometric (1:1) complexes with tRNA in solution. We show that only the polynucleotide X S13 complexes are able to select their cognate tRNAs. In particular, the affinity...

The complexation reactions between methylthymol blue (MTB) and Co2+, Ni2+, Cu2+, Zn2+ and Pb2+ ions have been studied in different water-methanol mixtures at pH 4.45 and 25 °C by a spectrophotometric technique. The stepwise stability constants of the resulting 1:1 and 2:1 (metal ion to ligand) complexes were determined from the absorban...

The mechanism of reaction of human erythrocyte hypoxanthine-guanine phosphoribosyltransferase was investigated by initial velocity, product inhibition, and isotope exchange studies. Although initial velocity data are compatible with a mechanism involving binary enzyme-substrate complexes, the product inhibition and isotope exchange studies indicate that the reaction is ordered with the formatio...