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Biomedical subjects

H Ueyama

Publications and source records attributed to H Ueyama.

At least 163 records · Page 9Linked to original sources
PubMed1979

Characterization of polyriboadenylate polymerase from Tetrahymena pyriformis.

Poly(A) polymerase [polyadenylate nucleotidyltransferase, EC 2.7.7.19] was extracted from Tetrahymena pyriformis. The enzyme was demonstrated to be present in three forms by column chromatography on DEAE-cellulose, and they were termed poly(A) polymerase Ia, Ib, and II in order of increasing affinity to the column. The properties of enzymes Ia and Ib were similar except that Ia utilizes poly(A) as a primer rather efficiently. Enzyme II differed from enzymes Ia and Ib not only in elution profile on DEAE-cellulose column chromatography but also in pH and temperature preferences, molecular weight, requirement for divalent cations, sensitivity to salts at high ionic strength, optimal primer concentration, and subcellular localization. The molecular weights of enzymes Ia and Ib measured by gel filtration were both 43,000, and that of enzyme II was 95,000. All three enzymes required Mn2+ for maximal activity; Mg2+ could replace Mn2+ in the reaction of enzyme II, but only partially. In the presence of 0.1 M ammonium sulfate the activities of enzymes Ia and Ib were both completely inhibited, whereas enzyme II still showed 42% of its original activity. These findings suggest that there are two distinct types of poly(A) polymerase in Tetrahymena pyriformis.

Animals↗
PubMed1979

Effect of alpha-tocopherol on the binding of benzo(a)pyrene to nuclear macromolecules.

The binding of metabolically activated 14C-benzo(a)pyrene (BP) to rat liver nuclei was studied. The nuclear framework structure, termed the nuclear matrix, was found to bind BP preferably. alpha-Tocopherol inhibited the binding of BP to nuclear macromolecules in the presence of phenobarbital (PB)-induced microsomes. alpha-Tocopherol decreased the level of BP metabolites in nuclei, though it did not inhibit the activation of BP by PB-induced microsomes.

Animals↗