Search results for "nucleic acid"
showing 10 items of 810 documents
Self-instructed condensation of amino acids and the origin of biological information
1984
In contemporary cells biological information is largely stored in nucleic acids. Therefore, a prerequisite in many theories on the origin of cellular life is the pre-existence of self-replicating polynucleotides that had to be formed by abiotic processes on the prebiotic Earth. It is usually assumed that the spontaneous synthesis of a self-replicating polynucleotide could take place readily. However, serious stereochemical obstacles exist which make such a synthesis extremely improbable. Amino acids, on the other hand, which are abundantly formed in prebiotic simulation experiments, are relatively easily polymerized to macromolecules (protoproteins) that share with modern proteins many prop…
Organometallic complexes with biological molecules. XV. Effects of tributyltin(IV)chloride on enzyme activity, Ca2+, and biomolecule and synthesis in…
2001
Considerable attention has been given in recent years to the possibility that xenobiotics in the environment may affect reproduction in animals. In this study, the relative impact of tributyltin(IV) (TBT) chloride, one of the most toxic environmental pollutants, was investigated using Ciona intestinalis ovary as a model system. The pleiotropic effects of TBT exposure are concentration dependent and include a decrease of ATP levels, lipid content and nucleic acid content and synthesis. In contrast, a marked increase in calcium (Ca2+) and glucose content is observed. Furthermore, TBT alters enzymatic activity, inhibiting creatine kinase and stimulating alkaline phosphatase and cholinesterase …
Nucleic Acids and Nuclear Proteins
1994
DNA deserves the most attention in any book dealing with molecular variety in animals. The complete genetic information of the organism is encoded in the order of the bases, and with it also is the whole spectrum of genetically determined variation within and between individuals. One can view DNA as a text in which each of the four letters at each position has a unique meaning. Some information and variety is lost en route from the DNA via RNA to the proteins and the complex morphological and physiological characters because only part of the DNA is transcribed into RNA, and not all RNA codes for proteins; furthermore, the genetic code is degenerate and the 64 possible triplet codons define …
Quantification of DNA and RNA: A Spectrophotometric Method
2003
Spectophotometric quantification is a very exact method of quantifying the content of nucleic acids in any sample. The purity of the sample can be simultaneously checked very easily. Keywords: DNA; RNA; spectrophotometric quantification
Simple models for nonlinear states of double-helix DNA
2006
Review type introduction is given to the simple modeling of DNA. Intrinsically simple modeling aims at understanding or explaining of some “core” phenomena, not giving any all-embracing model of the underlying system. As a consequence the amount of this type of models and their versions is large. Here we have restricted our contemplation to the most important lines in the path of theoretical understanding of DNA melting or denaturation which is one of the important phases occurring during DNAs replication and transcription processes. The model “line” initiated by Peyrard and Bishop shows the richness these simple models can have.
Epoxide Hydrolase Isoenzymes and their Individual Contribution to the Control of Toxic Metabolites
1991
Epoxides are highly strained three membered cyclic ethers which are formed in vivo by the microsomal cytochrome P450 dependent monooxygenases as intermediates of several important biosynthetic pathways (leukotriene A4, squalene 2, 3-oxide) and as metabolites of numerous xenobiotic compounds containing olefinic or aromatic double bonds. Further transformation of these epoxides may occur by either, rearrangement to phenols, aliphatic aldehydes, or ketones; by cytochrome P450 dependent reduction to the parent compound; or by spontaneous or enzymatic conjugation to gluta-thione. Epoxides may also bind covalently to cellular nucleophiles, such as proteins and nucleic acids thus eliciting carcino…
Revealing interactions between polyaza pyridinophane compounds and DNA/RNA polynucleotides by SERS spectroscopy
2014
Surface-enhanced Raman scattering spectroscopy (SERS) in the near-infrared region had been applied to study interactions of polyaza pyridinophanes with single stranded RNA and double stranded DNA and RNA polynucleotides. Studied compounds, PYPOD and PHENPOD, differed in the central aromatic moiety, pyridine and phenanthroline, respectively, which linked two cyclic amines. An intense scattering was obtained from molecules adsorbed onto the silver nanoparticles, showing nonlinear concentration dependence in the 6.5 × 10−8−6.5 × 10−5 M range. New bands in spectra of PYPOD/polynucleotide and PHENPOD/polynucleotide mixtures were assigned to vibrational modes of polynucleotide moieties involved i…
The interaction of transition metal complexes with deoxyribonucleic acid
2011
La presente tesi `e suddivisa in quattro capitoli. Il Capitolo 1 `e di carattere introduttivo. Nel Capitolo 2 viene trattata la sintesi e la caratterizzazione strutturale dei complessi di CuII, NiII e ZnII con il legante N,N’-Bis-5-(trietil ammonio metil salicilidene)-1,2- fenilendiammina. Inoltre, vengono riportati e confrontati i risultati dello studio della loro interazione con DNA nativo. Viene in particolare mostrato come l’interazione con DNA aumenti la stabilit`a fotochimica del complesso di ZnII. Infine, vengono evidenziati gli effetti del confinamento in cristalli liquidi sull’interazione del complesso di CuII e DNA.Nel Capitolo 3 `e riportata la sintesi e la caratterizzazione stru…
B‐DNA structure and stability: the role of nucleotide composition and order
2022
Abstract We have quantum chemically analyzed the influence of nucleotide composition and sequence (that is, order) on the stability of double‐stranded B‐DNA triplets in aqueous solution. To this end, we have investigated the structure and bonding of all 32 possible DNA duplexes with Watson–Crick base pairing, using dispersion‐corrected DFT at the BLYP‐D3(BJ)/TZ2P level and COSMO for simulating aqueous solvation. We find enhanced stabilities for duplexes possessing a higher GC base pair content. Our activation strain analyses unexpectedly identify the loss of stacking interactions within individual strands as a destabilizing factor in the duplex formation, in addition to the better‐known eff…
The endopolygalacturonase 1 from botrytis cinerea activates grapevine defense reactions unrelated to its enzyumatic activity
2003
A purified glycoprotein from Botrytis cinerea(strain T4), identified as endopolygalacturonase 1 (T4BcPG1) by mass spectrometry analysis, has been shown to activate defense reactions in grapevine (Vitis vinifera cv. Gamay). These reactions include calcium influx, production of active oxygen species, activation of two mitogen-activated protein kinases, defense gene transcript accumulation, and phytoalexin production. Most of these defense reactions were also activated in grapevine in response to purified oligogalacturonides (OGA) with a degree of polymerization of 9 to 20. In vivo, these active OGA might be a part of the released products resulting from endopolygalacturonase activity on plan…