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Biomedical subjects

R Ellis

Publications and source records attributed to R Ellis.

At least 145 records · Page 8Linked to original sources
PubMed1975

Regulation of chlorophyll synthesis in the green alga golenkinia.

Chlorophyll synthesis in Golenkinia is inhibited 10-fold by growth in darkness on acetate or by growth on elevated concentrations of acetate in the light, particularly if the growth medium contains low levels of nitrogen. Glucose has no such inhibitory effect. delta-Aminolevulinic acid, with a maximal effect at 0.01 m, but not its precursors, overrides the inhibitory effect of acetate and darkness, restoring chlorophyll synthesis. Glycine, succinate, and alpha-ketoglutarate, the precursors tested, all enter the cell. Cells forming chlorophyll produce significantly more aminolevulinic acid than do cells becoming bleached, further indicating the important regulatory role of this compound. Cyclic AMP has no effect on chlorophyll synthesis. These results are compared with those obtained studying other algae, and a mechanism relating light and acetate to chlorophyll formation is proposed.

Journal Article↗
PubMed1972

Origin of glycine from acid hydrolysis of the -lactam antibiotic A16886B.

Structural analysis of two new beta-lactam antibiotics, A16884A and A16886B, indicated that they, like cephalosporin C, were composed of modified valine and cysteine residues, and alpha-aminoadipic acid. However, acid hydrolysis of A16886B and A16884A produced three times as much glycine as did hydrolysis of cephalosporin C under the same conditions. Samples of A16886B-(14)C-6 and A16886B-(14)C-8 were prepared by the addition of cysteine-(14)C-3 and cystine-(14)C-1 to fermentations of Streptomyces clavuligerus. The specific activity of glycine obtained from hydrolysis of A16886B-(14)C-6 was considerably higher than that from hydrolysis of A16886B-(14)C-8. An explanation for the difference in amounts of glycine obtained from hydrolysis of these antibiotics is discussed.

Carbamates↗