Ab initio surface hopping dynamics calculations were performed to study the photophysical behavior of cytosine and guanine embedded in DNA using a quantum mechanical/molecular mechanics (QM/MM) approach. It was found that the decay rates of photo excited cytosine and guanine were affected in a completely different way by the hydrogen bonding to the DNA environment. In case of cytosine, the geom...

Abstract: Guanine-rich nucleic acids are able to self-assemble into G-quadruplex four-stranded secondary structures, which are found at the level of telomeric regions of chromosomes, oncogene promoter sequences and other biologically-relevant regions of the genome. Due to their extraordinary stiffness and biological role, G-quadruples become relevant in areas ranging from structural biology to ...

A B S T R A C T We have previously described a 14-yrold boy with hyperuricemia, renal failure, and accelerated purine production resistant in vivo and in vitro to purine analogs. This patient demonstrated normal red cell hypoxanthine-guanine phosphoribosyltransferase (HPRT) heat stability, electrophoresis at high pH, and activity at standard substrate levels. In the present report an abnormal H...

Homogeneous guanine deaminase (guanine aminohydrolase, EC 3.5.4.3) is a single polypeptide chain of mean molecular weight of 55,000, as determined by Sephadex gel filtration and sodium dodecyl sulfate polyacrylamide disc gel electrophoresis. Irreversible inactivation was observed upon incubation with P-chloromercuribenzoate, at a concentration of 1.0 x lop4 M. Iodoacetic acid and iodoacetamide ...

Hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) has been purified 23,000-fold from normal human erythrocytes. The purification includes affinity chromatography on a GMP column. The subunit molecular weight of the enzyme obtained from this purification is 24,000. The finding of four protein species after cross-linkage of the highly purified enzyme with dimethylsuberimidate, dimethyla...

A mutant form of human hypoxanthine-guanine phosphoribosyltransferase (HPRTToronto) was isolated from erythrocytes of a male patient with gout due to a partial deficiency of enzyme activity. The tryptic peptides of HPRTToronto were mapped by reverse-phase high pressure liquid chromatography in an attempt to define the precise abnormality in its primary structure. Sequence analysis of the single...

Abstract Summary: Guanine nucleotide exchange factors (GEF) control the rate-limiting step of physiologic RAS activation. In this issue Cancer Discovery, Hofmann and colleagues describe discovery a selective inhibitor targeting GEF, SOS1, along with its preclinical effects in suppressing KRAS-mutant tumor growth. See related article by et al., p. 142.

Two mononuclear RuIII complexes of formula trans-[RuCl4(Hgua)(dmso)]·2H2O (1) and trans-[RuCl4(Hgua)(gua)]·3H2O (2) [Hgua = protonated guanine (gua), dmso dimethyl sulfoxide] have been synthesized characterized magnetostructurally. 1 2 crystallize in the monoclinic system with space groups P21/n Pc, respectively. Each ion is bonded to four chloride ions one or two nitrogen atoms from molecules ...