350 rub
Journal №3 for 2012 г.
Article in number:
Peculiar properties of akonitat hydratase enzyme system in the organs of rats with alloxan diabetes
Keywords: Glyoxylate cycle an alloxan diabetes aconitate hydratase tricarboxylic acid cycle gluconeogenesis
Authors:
A.T. Eprintsev, H. Al Benayed Saba, M.Yu. Syromyatnikov, A. Gati Mohannad
Abstract:
The aim of this work was to study the functioning of aconitate hydratase in cells and tissues of different organs in rats in conditions of alloxan diabetes. The study was performed using male inbred rats (Rattus rattus L.). Induction of diabetes was carried out by administration of 5 % alloxan subcutaneously. Determination of enzyme activity was carried out at 25 °C using spectrophotometric methods. One unit of activity was the amount of enzyme which converts 1 μM substrate or forming 1 μM product for 1 minute at 25 ° C and optimum pH. Electrophoretic study of proteins was performed at 7,5 % polyacrylamide gel. Administration alloxan experimental rats contributed to the increase of glucose in the blood to 19.4 mg / dL 10 days after injection. On 10 day at diabetes the intensification of a respiratory metabolism is observed: activity of the majority of enzymes tricarboxylic acid cycle is enlarged. Acceleration of work of a citric acid cycle is caused by occurrence of new metabolic requirements. The enzyme of gluconeogenesis - fosfoenolpiruvat-karboksikinaza is induced. In the liver of rats with alloxan diabetes induction of marker enzymes glyoxylate cycle (malate synthase, isocitrate lyase) was observed. Reducing the activity of pyruvate kinase and glucose-6-phosphate dehydrogenase was the indication of the inhibition of enzymes glycolysis and the pentose phosphate path in the animals liver in the early stages. Aconitate hydratase was found in all investigated organs in rats, in normal conditions and in experimental diabetes. Established variation in enzyme activity depends on the organ. There are two isoforms of aconitate hydratase, specifically localized in the mitochondrial and cytoplasmic fractions. In experimental animals exposed to alloxan diabetes, there is more than a threefold increase of activity in cytoplasm as well as two-fold - the mitochondrial isoform of aconitate hydratase in rat hepatocytes. Under the conditions of experimental diabetes is observed induction of a new form of aconitate hydratase with a relative electrophoretic mobility (Rf 0,81). The additional isoform Aconitate hydratase indicates, apparently, on the induction of additional metabolic pathway - the glyoxylate path in organs of rats in experimental diabetes required for gluconeogenesis.
Pages: 38-44
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