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Biomedical subjects

S Takada

Publications and source records attributed to S Takada.

At least 379 records · Page 21Linked to original sources
PubMed1979

Studies on rat liver argininosuccinate synthetase. Inhibition by various amino acids.

Inhibition studies of crystallized rat liver argininosuccinate synthetase [EC 6.3.4.5] are described. 1. L-Argininosuccinate, L-histidine, and L-tryptophan inhibited the enzyme activity at saturating amounts of the substrates. 2. L-Norvaline, L-argininosuccinate, L-arginine, L-isoleucine, and L-valine competitively inhibited the enzyme activity at a low concentration of L-citrulline, with Ki values of 1.3 x 10(4) M, 2.5 X 10(-4) M, 6.7 X 10(-4) M, 6.3 X 10(-4) M, and 6.0 x 10(-4) M, respectively. 3. L-Argininosuccinate and L-arginine competitively inhibited the enzyme activity at a low concentration of L-aspartate, with Ki values of 9.5 x 10(-4) M and 1.2 x 10(-3) M, respectively. 4. The modes of inhibition by L-histidine were mixed-noncompetitive, uncompetitive, and noncompetitive types with respect to L-citrulline, L-aspartate, and ATP, respectively. 5. When the enzyme was preincubated with L-citrulline, the enzyme activity was slightly increased in the presence of a low concentration of L-histidine in the assay mixture. 6. The conformation of the enzyme was markedly changed by the addition of L-histidine as judged from the CD spectrum. This change was partially reversed by incubation with L-citrulline.

Amino Acids↗
PubMed1977

Interactions of rodent malarial parasites with Friend erythroleukemia cells in vitro.

The ability of Plasmodium chabaudi and P. yoelii to bind to Friend erythroleukemia cells in vitro was examined. Extensive binding of P. yoelii and weaker binding of P. chabaudi was observed. Binding to mouse fibroblasts was not seen, although there was some binding to cells of a mouse mastocytoma. The binding of P. yoelii to Friend cells was sensitive to specific antiserum. The development of P. berghei and P. yoelii in Friend cells was followed by microscopic examination and measurement of the infectivity of those cells in mice. Friend cells infected with both species appeared to develop morphologically normal intracellular forms of the parasites. P. yoelii-infected cells were infective in sensitive mice for 3 days after addition of the parasites, and this infectivity was not sensitive to treatment in vitro with mouse anti-P. yoelii serum.

Animals↗