Eremothecium ashbyii is one of a number of organisms which produce considerable amounts of riboflavin, most of which is secreted by the cells into the medium (Guilliermond, 1935). The investigations of Schopfer (1944) and Schopfer and Guilloud (1945) resulted in the development of a synthetic medium for this organism which permitted growth and riboflavin production to occur under chemically def...

The first reaction in pyrimidine and arginine biosynthesis in Escherichia coli is catalyzed by a single enzyme, carbamoyl-phosphate synthetase (EC 6.3.5.5), the product of the carAB operon. Expression of this operon is cumulatively repressed by arginine and pyrimidines. The nucleotide sequence of the carAB control region was determined and transcriptional starts were localized. Two adjacent pro...

A revival of interest has taken place in recent years in the possibility of interference with mam malian nucleic acid biosynthesis by means of an tagonists of the free pyrimidines. Early studies appeared to show that, while orotic acid (1, 48) and the sugar derivatives of the pyrimidines (19, 20) are extensively incorporated into both RNA and DNA, the incorporations of free uracil, cytosine, an...

The active forms of 6-(p-hydroxyphenylazo)-uracil and 6-(p-hydroxyphenylazo)-isocytosine were isolated and identified as their respective hydrazino derivatives. These arylhydrazino pyrimidines selectively inhibited a chromatographically distinct DNA polymerase from Bacillus subtilis. The actions of the reduced drugs on this polymerase were identical to those observed on ATP-dependent DNA synthe...

Several pyrazolo [1, 5-a] pyrimidines derivative were prepared by the condensation of substituted of α, βunsaturated carbonyl compounds (chalcones) with substituted 5-amino pyrazole as an alternative polyethylene glycol (PEG-400) as green reaction medium. The reaction is clean with excellent yield, shorter reaction time. The entire synthesized products were characterized by spectral analysis. F...

A sublimation technique was developed to isolate purines and pyrimidines directly from lambda-deoxyribonucleic acid (lambda-DNA) and Escherichia coli cells. The sublimation of adenine, cytosine, guanine, and thymine from lambda-DNA was tested under reduced pressure (approximately 0.5 Torr) at temperatures of >150 degrees C. With the exception of guanine, approximately 60-75% of each base was su...

a simple extremely fast and efficient approach for the synthesis of substituted indazole ingood to excellent yield catalyzed by using silica sulfuric acid (ssa) in dmso solvent at roomtemperature. this is solid state reaction have been attracting the synthetic organic chemist asthey provided enhance reaction rates, less environmental pollution, greater selectivity, cleanerproducts and manipulat...

objectives: the aim of this research was the development of 111in-labeled porphyrins as possible radiopharmaceuticals for the imaging of tumors. methods: ligands, 5, 10, 15, 20-tetrakis (3, 5-dihydroxyphenyl) porphyrin) (tdhpp), 5, 10, 15, 20-tetrakis (4-hydroxyphenyl) porphyrin (thpp) and 5, 10, 15, 20-tetrakis (3,4-dimethoxyphenyl) porphyrin) (tdmpp) were labeled with 111incl3 (produced from ...