Nucleotides oxidation

Walker, G. A. and Kilgour, G. L. 1965. Pyridine nucleotide oxidizing enzymes of Lactobacillus casei. II. Oxidase and peroxidase. Arch. Biochem. Biophys. Ill, 534-539. 

Azaguanosine was obtained by the action of phosphomonoesterase on the nucleotide. Oxidation of the nucleoside with sodium metaperiodate, followed by incubation at pH 10 at 37°, released 8-azaguanine. 

Sugar nucleotide oxidation pathway (SNOP, Steps 6-8)... 

There have been several reports of the complex electrochemical behavior of single-strand and duplex DNA absorbed on electrode surfaces [48]. However, there have been no reports to date of the measurement of nucleotide oxidation or reduction potentials in duplex DNA. Johnston and coworkers [49] have used electrochemical methods to study the dynamics of the selective oxidation of guanine in single-strand and duplex DNA by Ru(bpy)3 + which is generated by oxidation of Ru(bpy)3 + (Eqs. 3 and 4). 

ADH Antidiuretic hormone, vasopressin DPN+ Diphosphopyridine nucleotide (oxidized)... 

A relatively recent indirect assay was set up by Paoletti (108). The assay consists of a sequence of reactions that generate superoxide from molecular oxygen in the presence of EDTA, manganese(II) chloride, and mercaptoethanol (108-110). The reactions are monitored by following the oxidation of NAD(P)H by superoxide radicals through a decrease of absorbance at 340 nm, which corresponds to the maximum absorbance of NAD(P)H. The addition of SOD (scavenging superoxide) inhibits nucleotide oxidation (Fig. 14). At variance with the previous assays, whereby C3itochrome c is reduced by superoxide, this method relies on the oxidation of NAD(P)H and, in theory, makes the detection less susceptible to aspecific reduction by common cellular components. The assay is very sensitive to the EDTA/Mn ratio and to the mercaptoethanol concentration, both of which affect nucleotide... 

The conversion of hexose into uronic acid and pentose units of cell wall polysaccharides in higher plants may occur, not only by the sugar nucleotide oxidation pathway, which leads to UDP-uronate, but also by the myoinositol oxidation pathway. In this case, the homocyclic inositol ring is split, oxidized at C(6) and concurrently replaced by a heterocycle with an —O— bridge between C(l) and C(5), as shown by label experiments. Glucuronic acid can be generated in this way. 

Release of Ca from intact rat liver mitochondria can be induced by oxidation of mitochondrial pyridine nucleotides. This was first shown by the group of Lehninger [8] who oxidized mitochondrial pyridine nucleotides with acetoacetate or oxaloacetate at the level of the citric add cycle. Our group [9 used hydroperoxides, known to be produced by the respiratory chain of mitochondria and to be linked to pyridine nucleotides by glutathione peroxidase and reductase, to induce Ca release and oxidation of pyridine nucleotides. Orrenius and co-workers employed [10] menadione (2-methyl-l, 4-naphthoquinone) to induce pyridine nucleotide oxidation and Ca release. The latter... 

Oxidation alone of pyridine nucleotides is not sufficient to induce Ca release. In the presence of ATP, the hydroperoxide-induced pyridine nucleotide oxidation is even accelerated, yet pyridine nucleotide hydrolysis and Ca release are inhibited [11]. Similar observations were made during the menadione-induced Ca release [10]. When liver mitochondria are treated with N-ethyl maleimide to lower intramitochondrial glutathione, both oxidation of pyridine nucleotides and Ca " release are inhibited (S. Baumhuter, C. Richter, unpubl.). Finally, both pyridine nucleotide hydrolysis and Ca release show the same sigmoidal dependence on the mitochondrial Ca load [15]. Thus, there is clear, albeit circumstantial, evidence that pyridine nucleotide hydrolysis and Ca " release are functionally related. The link between the two processes may be protein ADP-ribosylation. 

Ca release from intact rat liver mitochondria is induced by compoimds that oxidize intramitochondrial pyridine nucleotides. Oxidation alone of pyridine nucleotides is not sufficient to cause Ca release. Release is, however, observed when oxidized pyridine nucleotides are hydrolyzed at the N-glycosidic bond linking ADP-ribose and nicotinamide. Both pyridine nucleotide hydrolysis and Ca release are very similarly dependent on the intramitochondrial Ca load. 

Flavin nucleotide—bound to protein (reduced) Flavin nucleotide (oxidized) -0.06... 

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