PubMed · 6986034
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P Newmark. 1980-01-24. Engineered E. coli produce interferon.. https://doi.org/10.1038/283323a0
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Four monosaccharides (glucose, galactose, mannose and fructose) and one disaccharide (maltose) were subjected to high-performance liquid chromatography with UV or refractive index detection. Various profiles such as broad, tailed and splitted peaks were produced, depending on column temperature and eluent flow-rate because these saccharides underwent isomerization. In contrast, alpha-methylglucoside, a non-converting derivative, always produced a sharp peak. By analyzing these profiles kinetic constants of the isomerization were obtained and compared with the literature data.
The reactions of sulphonyl peroxyl radicals with DNA and its components at low temperatures are investigated through use of electron spin resonance spectroscopy. Radiolysis of cysteine sulphinic acid solution in oxygenated aqueous 5 mol dm-3 LiCl glass has been employed to generate sulphonyl peroxyl radicals, CysSO2OO.. The mechanism of production is a two-step process involving the oxidation of the sulphinate (CysSO2-) to the sulphonyl radical (CysSO2.) by radiolytically produced Cl2- followed by oxygen addition to CysSO2.. Sulphonyl peroxyls are shown to be reactive toward DNA and nucleotides in low temperature glasses, giving rise to carbon-based peroxyl radicals. However, of the DNA bases only thymine was found to react readily. The thymine methyl group contains a relatively weak C-H bond which makes it easily abstractable. DNA nucleosides and nucleotides are likely attacked by CysSO2OO. by abstraction from the sugar C-H bonds. The C(1) position of deoxyribose ring of model nucleosides is suggested to be a preferred site for attack at low temperatures. The reaction with double-stranded DNA at higher temperatures may occur at the more accessible C(4) position. CysSO2OO. is also shown to react with a number of methyl substituted uracils, producing the highly persistent 5-oxouracil-6-yl radicals. The reaction mechanism proposed involves the addition of CysSO2OO. to pyrimidine 5,6-double bonds followed by elimination of cysteine sulphonic acid.
A method is described for analysis of the intracellular concentrations of metabolic intermediates of the Embden-Meyerhof-Parnas pathway, the Entner-Doudoroff pathway, the pentose phosphate pathway, and the tricarboxylic acid cycle in cell pool extracts of Escherichia coli. A single anion-exchange HPLC run of 40 min allowed resolution of 27 anionic metabolite standards. Detection limits of 0.1 nmol per injection were achieved by use of a conductivity detector equipped with an anion self-regenerating suppressor and a uv detector. A boiling water extraction procedure was used to prepare cell pool extracts. Cochromatography of cell pool extracts and metabolite standards was used to confirm the identities of metabolites in the cell pool. As many as 16 metabolites could be detected and quantified in the cell pool extracts by using the described HPLC method. An analysis of metabolite concentrations in E. coli showed the dynamics of glucose metabolism during a 2-min transition from starvation to steady-state metabolism following addition of glucose. The ease and power of this method suggests general utility for in vivo metabolite analysis in a variety of experimental systems.