Fructose, 1,6-diphosphate mitigates CCl4 suppressed nitric oxide synthase activity in rats.

Effect of fructose 1,6-diphosphate (FDP) and carbon tetrachloride (CCl4) were studied individually and in combination on rat endothelial (ET) and smooth muscle cell (SMC) nitric oxide synthase (NOS) activities in vivo, inhibition of ET and SMC NOS activity in CCl4 treated rats was reversed in FDP + CCl4 treated animals. Cellular based NOS activity was significantly increased in FDP treated group of rats when compared to non treated controls. The results suggest a significant increase in NOS in rats treated with a combination of FDP + CCl4 thus overcoming the suppression of NOS exposed to CCl4 alone.

Aggregation of banana pyrophosphate fructose 6-phosphate 1-phosphotransferase by glycerol.

Addition of glycerol during purification of banana (Musaceae, Musa cavendishii) pyrophosphate fructose 6-phosphate 1-phosphotransferase [(PFP), EC 2.7.1.90] initiated molecular aggregation of the enzyme. The aggregation process was dependent on the glycerol concentration. The native enzyme (66 kDa molecular mass) showed enhanced activity at 3% (V/V) or less of glycerol concentration. Glycerol concentration between 4 and 5% (V/V) affected a gradual and sequential aggregation of native form of the enzyme. These aggregated forms had molecular masses of 135, 200 and 270 kDa. The 135 and 200 kDa forms were stable for about 72 hrs and prolonged storage over 2 weeks resulted in the formation of the 270 kDa form. Concentration over 5% could reduce the time required for aggregation. Fru2.6 bis P activated the enzyme over ten fold, but did not help in the aggregation process. Studies on the role of glycerol on PFP specific activity suggested a difference in the activation process compared to that by Fru2.6bis P. Replacement of Hepes buffer by Tris increased the Fru2.6 bis P requirement for maximum activation by around 10 fold. Removal of glycerol from the buffer media resulted in almost complete inactivation of the enzyme.