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Biomedical subjects

T Akazawa

Publications and source records attributed to T Akazawa.

At least 181 records · Page 10Linked to original sources
PubMed1969

Enzymic Mechanism of Starch Breakdown in Germinating Rice Seeds II. Scutellum as the Site of Sucrose Synthesis.

In a close parallel to the developmental pattern of alpha-amylase activity, a rapid increase of maltase activity occurred in the endosperm tissue of germinating rice seeds after about 4 days of the seed imbibition. The overall pattern of the 2 hydrolytic enzyme activities strongly suggest that amylolytic breakdown is the major metabolic route of starch utilization in the germinating rice seeds. Results of the chemical analyses of sugar constituents as well as the measurements of sucrose synthetase activity show that the scutellum is the site of sucrose synthesis in the germinating rice seeds. It is thus supported that glucose derived from the reserve starch in endosperm is transported to scutellum, where it is converted to sucrose. Sucrose is further mobilized to the growing tissues, shoots and roots.

Journal Article↗
PubMed1968

Pyruvate Kinase Activity of Wheat Plants Grown under Potassium Deficient Conditions.

The activity of pyruvate kinase was determined in the first leaves of wheat plants grown under K(+)-deficient conditions. An enhancement of the enzyme activity compared with the normal plants was found to start from eighth day of growth, and about 4-fold increase in the enzyme activity was observed in 14-day wheat leaves. The addition of K(2)SO(4) to the nutrient solution given to the K(+)-deficient plants at tenth day resulted in the restoration of the enzyme activity to the normal level after 3 days. The levels of K(+) as well as carbohydrates and chlorophyll were found to return normal over the same period. These findings are discussed in relation to the metabolic pattern of plants at the early stages of K(+)-deficiency.

Journal Article↗
PubMed1967

Biosynthesis of starch in chloroplasts.

The enzymic synthesis of ADP-glucose and UDP-glucose by chloroplastic pyrophosphorylase of bean and rice leaves has been demonstrated by paper chromatographic techniques. In both tissues, the activity of UDP-glucose-pyrophosphorylase was much higher than ADP-glucose-pyrophosphorylase. Glycerate-3-phosphate, phosphoenolpyruvate and fructose-1,6-diphosphate did not stimulate ADP-glucose formation by a pyrophosphorylation reaction. The major metabolic pathway for UDP-glucose utilization appears to be the synthesis of either sucrose or sucrose-P. On the other hand, a specific precursor role of ADP-glucose for synthesizing chloroplast starch by the ADP-glucose-starch transglucosylase reaction is supported by the coupled enzyme system of ADP-glucose-pyrophosphorylase and transglucosylase, isolated from chloroplasts. None of the glycolytic intermediates stimulated the glucose transfer in the enzyme sequence of reaction system employed.

Chloroplasts↗