Nucleic acids, phosphate from, after

Magnesium-induced coprecipitation (Karl and Tien, 1992) involves the precipitation of brucite (Mg(OH)2) from seawater by the addition of base. It was observed that phosphorus compounds, including organic phosphates, coprecipitate with the brucite, and this was used as the basis for preconcentration of phosphorus prior to analysis of total phosphorus in the collected precipitate. Nucleic acids have also been determined quantitatively by precipitation with cetyltri-methylammonium bromide, with DNA and RNA determined at xg/l levels by fluoromet-ric and colorimetric procedures (Karl and Bailiff, 1989). Iron and barium salts are also commonly used as precipitants to isolate inositol phosphates after selective oxidation of organic phosphorus (Cosgrove, 1980). 

For some applications or for quality assurance, it can be necessary to control whether instruments, surfaces, reaction tubes, or used buffers are contaminated with DNA, RNA, DNAse, or RNAse. For the detection of DNAse or RNAse, known amounts of DNA or RNA are incubated with the suspected buffers or in the tubes at 37 to 40°C for 30 to 60 min. After this, real-time PCR is performed with the untreated DNA or RNA as control. If the analysis of incubated DNA or RNA shows a higher value than the control, and the internal process control gives no hint of inhibition, DNAse or RNAse was present. For the detection of DNA or RNA contaminations, humid swab samples (in TE or phosphate-buffered saline buffer) have to be collected from surfaces or instruments and the nucleic acids extracted into the TE buffer. The buffer can also be incubated in the suspected reaction tube or pipette tip. Real-time PCR is performed with universal primers specific for cytochrome b, human DNA, or any other DNA/RNA that is identified as a source of contamination in the laboratory. 

Phaseolus vulgaris, Xanthiumpetmsylvanicum). LD50 (mouse p.o.) 2 g/kg, (mouse i. v.) 770 mg/kg. Biochemistry O. is a biosynthetic precursor of pyrimidine nucleotides. The biosynthesis proceeds from L- aspartic acid and carbamoyl phosphate with subsequent dehydrogenation. Reaction with 5-phospho-a-D-ribofuranose 1-diphosphate and loss of pyrophosphate furnishes OMP and, after decarboxylation, uridine 5 -monophosphate. This de novo synthesis of pyrimidine bases is an important biochemical process in the biosynthesis of nucleic acids (see LiO). For synthesis, see Lit.. ... 

Purines may also be derived from the nucleic acids present in animal and plant foods. After liberation in the course of digestion they are absorbed and react with PRPP from which they receive the ribose phosphate moiety. 

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