Guanine quadruplexes are four-stranded DNA/RNA structures composed of a guanine core (vertically stacked tetrads) and peripheral groups (dangling ends and/or loops). Such dual structural arrangement the nucleobases favors their photoionization at energies significantly lower than ionization potential. This effect is important with respect to oxidative DNA damage for applications in field opto...

In order to better define the mechanism and the products of guanine oxidation within DNA, we investigated the details of the mechanism of guanine oxidation by a metalloporphyrin, Mn-TMPyP, associated to KHSO(5) on oligonucleotides. We found that the three major products of guanine oxidation are formed by independent reaction routes. The oxidized guanidinohydantoin (1) and the proposed spiro com...

Corynebacterium species lacks the ability to convert either xanthine or guanine to adenine. This defect and the use of the purine nucleoside antibiotic decoyinine, which blocks the conversion of xanthosine monophosphate --> guanosine monophosphate, permit an experimental design in which the interconversion of purines is largely prevented. Cultures of this organism were grown in the presence of ...

We present the IR-UV double resonance spectrum of guanine monohydrate in the region 3100 cm(-1) to 3800 cm(-1) along with the energies and frequencies of these structures calculated at the non-empirical correlated ab initio RI-MP2/cc-pVDZ level. We assign the structures of guanine-water clusters by comparing the experimental spectra with the ab initio calculations and with the IR spectra of the...

The association of agonists with muscarinic receptors in membranes from bovine brain was affected only slightly by guanine nucleotides. However, solubilization of these membranes with deoxycholate and subsequent removal of detergent resulted in a preparation of receptors with increased affinity for agonists and a large increase in response to guanine nucleotides. Chromatography of deoxycholate ...

the effect of interactions of various ia and iia cations with two positions of the adenine-thymine (a−t) and guanine-cytosine (g−c) base pairs on the geometries and individual hydrogen bond (hb) energies have been investigated by using the atoms in molecules (aim) method at the b3lyp/6-311++g(d,p) level of theory. the cations that possess higher charge/radius (q/rad) ratio make higher changes o...

1. Guanine deaminase activities in homogenates and supernatant fractions of liver and brain of rat and mouse were elevated by administration of guanine to the animals. The maximum induction in mouse tissues occurred within 24h and in rat tissues within 48h. 2. Mitochondria of rat (but not mouse) liver and brain contain an inhibitor of supernatant guanine deaminase, and this was also increased b...

Purine riboswitches are RNA regulatory elements that control purine metabolism in response to intracellular concentrations of the purine ligands. Conformational changes of the guanine riboswitch aptamer domain induced by guanine binding lead to transcriptional regulation of genes involved in guanine biosynthesis. The guanine riboswitch aptamer domain has three RNA helices designated P1, P2, and...

Since guanine is a normal constituent of nucleic acids, the possibility of the direct incorporation of this purine is of great significance in the biosynthesis of nucleic acids. Earlier reports in the literature indicated that preformed guanine was not utilized for nucleic acid production in the rat (1, Z), but more recent evidence suggested that a trace of guanine may be incorporated in the nu...