Steady state kinetics of hypoxanthine guanine phosphoribosyltransferase-catalyzed reactions are studied. The results obtained suggest that IMP, GMP, P-Rib-PP, and pyrophosphate bind to the same enzyme form, while hypoxanthine and guanine bind to a different form. Guanine activates IMP-pyrophosphorolysis. During the reaction guanlne and IMP are consumed with formation of GMP and hypoxanthine (IM...

The glass surface modification with 3-(mercaptopropyl) trimethoxysilane (MPTS), gold nano-particles (GN) and guanine rich single strand DNA (ss-DNA) was utilized as a novel and efficient platform for sensing trace concentration of methylene blue (MB) by an inexpensive spectrophotometric method. Methylene Blue (MB) can interact with the guanine base of single strand DNA and absorbed onto glass s...

The hydration of biomolecules is vitally important in molecular biology, so in this paper thesolvation energy and radial distribution function of DNA bases have been calculated by theMonte Carlo simulation.The geometries of isolated Adenine, Guanine, Cytosine, and Thyminehave been optimized using 6-31+G(d,p) basis function sets. These geometries then will be used inthe Monte Carlo calculation o...

The importance of the depletion of guanine nucleotides in cellular toxicity was compared to that of the depletion of adenine nucleotides following the inhibition of early de novo purine bio synthesis in the mouse T lymphoma (S-49) cell line. Early de novo purine biosynthesis was blocked with 6-methylmercaptopurine ribonucleoside (6MMPR), while adenine and guanine nucleotide biosyntheses were in...

We isolated a strain of Escherichia coli K-12 in which the lac structural genes are fused to the purB control region and used this strain to study the regulation of the purA and purB loci. The purA locus was derepressed in response to either limiting adenine or guanine growth conditions in the presence of excess guanine or adenine, respectively. The presence of hypoxanthine in the culture mediu...

The Lesch-Nyhan syndrome is characterized clinically by choreoathetosis, spasticity, selfmutilation, and mental and growth retardation. Biochemically, there is a striking reduction of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity in affected individuals. We have examined erythrocytes from 14 patients with the Lesch-Nyhan syndrome for the presence of hypoxanthine-guanine phosph...