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Biomedical subjects

R D Simoni

Publications and source records attributed to R D Simoni.

100 records · Page 6Linked to original sources
PubMed1972

Coupling of energy to active transport of amino acids in Escherichia coli.

Active transport of amino acids in isolated membrane vesicles of E. coli ML 308-225 is stimulated by oxidation of D-lactate, and this stimulation is dependent on electron transport [Kaback, H. R. & Milner, L. S. (1970) Proc. Nat. Acad. Sci. USA 66, 1008]. In attempting to relate these results to amino-acid transport in intact cells, we isolated mutants of E. coli ML 308-225 that contain defects in D-lactate dehydrogenase (EC 1.1.2.4) and electron transport. Intact cells of these mutants are normal for transport of proline and alanine. We also isolated mutants defective in Ca,Mg-stimulated ATPase (EC 3.6.1.3), which is responsible for coupling electron transport to the synthesis of ATP. These mutants are defective in their ability to transport proline and alanine, as measured both in cells and isolated membrane vesicles. A possible role for the ATPase in coupling energy to active transport is discussed.

Adenosine Triphosphatases↗
PubMed1969

Genetic analysis of carbohydrate transport-deficient mutants of Salmonella typhimurium.

Mutants (car) isolated from Salmonella typhimurium were unable to utilize or ferment the following carbohydrates (all d-configuration): glucose, fructose, mannose, N-acetylglucosamine, sorbitol, mannitol, maltose, melibiose, and glycerol. The mutants did utilize galactose, glucose 6-phosphate, gluconic acid, glucuronic acid, pyruvate, and l-lactate. Biochemical analysis showed that there were two classes of mutants, each lacking one component of a phosphotransferase system. CarA mutants were deficient in enzyme I; carB lacked the phosphate carrier protein, HPr. Mapping experiments showed that the carA gene was located near pro; the carB gene mapped near purC.

Biological Transport↗