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Biomedical subjects

T Akazawa

Publications and source records attributed to T Akazawa.

At least 163 records · Page 9Linked to original sources
PubMed1972

Biocarbonate Effect on the Photophosphorylation Catalyzed by Chromatophores Isolated from Chromatium Strain D: XII. Structure and Function of Chloroplast Proteins.

Photophosphorylation catalyzed by chromatophores prepared from Chromatium strain D was stimulated by bicarbonate. The stimulative effect was pH dependent and the lower the pH the more marked the activation. At pH 8.0, bicarbonate (8 mm) exhibited a negligible effect, whereas at pH 7.0 approximately a 5-fold activation was observed. The apparent activation constant of bicarbonate was determined to be approximately 10.2 mm, at which concentration approximately a 7-fold activation of photophosphorylation was observed.

Journal Article↗
PubMed1970

alpha-Amylase Isozymes in Gibberellic Acid-treated Barley Half-seeds.

The presence of multiple forms of alpha-amylase in gibberellic acid-treated embryoless barley half-seeds was demonstrated by separation on diethylaminoethyl-Sephadex and isoelectric focusing polyacrylamide gel disc electrophoresis. Two major alpha-amylase fractions (A and B), each consisting of two to three isozyme components, were purified. alpha-Amylase fractions A and B were distinguishable in their reaction patterns. The optimal pH of fraction A alpha-amylase was found to reside in the acidic side (pH 5.0), as was determined by analyzing the reducing sugars formed as well as the paper chromatographic detection of reaction products. At neutral pH, 6.9, fraction A exhibited weak amylolytic activity in forming maltose. The alpha-amylase activity in fraction A was markedly stimulated by heat treatment (70 C/15 minutes). Fraction B, constituting a major part of amylases in the endosperm extract, was also found to be composed of alpha-amylase, as evidenced by the loss of enzyme activity upon allowing fractions A and B to stand at pH 3.3 for a prolonged period. The possible physiological function of the two different types of alpha-amylase in the carbohydrate breakdown of barley seeds is discussed.

Journal Article↗
PubMed1970

Enzymic Mechanism of Starch Breakdown in Germinating Rice Seeds: III. alpha-Amylase Isozymes.

The formation of amylase isozymes in germinating rice (Oryza sativa) seeds was studied by isoelectric focusing on polyacrylamide gel disc electrophoresis. Time sequence comparisons of the amylase zymogram were made between extracts from gibberellic acid-treated embryoless and embryo-attached half-endosperm of rice seeds. In both cases, 4 major and 9 to 10 minor isozyme bands were detectable at the maximal stage of the enzyme induction. However, in the embryo-attached half-seeds, bands started to diminish after the 5th day of incubation, in agreement with the results of time sequence analyses of enzyme activities. Nearly identical patterns of amylase isozyme bands on a polyacrylamide gel disc electrophoresis in combination with isoelectric focusing indicate the intrinsic role of gibberellic acid in the starch breakdown in germinating rice seeds. We tentatively assign the newly synthesized enzymes to be alpha-amylases based on experimental results concerning the lability of the preparation on a prolonged treatment at pH 3.3 and the stability on heat treatment for 15 minutes at 70 C.

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