Activities Of Pentose Phosphate Pathway Enzymes Research Articles

Effects of Timolol Treatment on Pancreatic Antioxidant Enzymes in Streptozotocin-induced Diabetic Rats: An Experimental and Computational Study.

SummaryBackgroundThe study aimed to investigate whether timolol-treatment has a beneficial effect on pentose phosphate pathway enzyme activities such as glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGDH) enzyme activities and cAMP level in streptozotocin-induced diabetic rats in pancreatic tissuesMethodsDiabetes was induced by streptozotocin (STZ) in 3-month old male Wistar rats. The diabetic rats were treated with timolol (5 mg/kg body weight, for 12 weeks) while the control group received saline. Enzyme activities were determined in pancreas tissue. To support our results, we performed in silico calculations, using Protein Data Bank structures.ResultsTimolol treatment of STZ-induced diabetic rats had no noteworthy effect on high blood-glucose levels. However, this treatment induced activities of G6PD and 6PGDH in diabetic rats. Timolol treatment significantly increased cAMP level in diabetic pancreatic tissue. We found that timolol cannot bind strongly to either G6PD or 6PGD, but there is a relatively higher binding affinity to adenylyl cyclase, responsible for cAMP production, serving as a regulatory signal via specific cAMP-binding proteins.ConclusionsOur data point out that timolol treatment has beneficial effects on the antioxidant defence mechanism enzymes in the pancreas of STZ-induced diabetic rats.

Metabolism Peculiarities of Bacteria of the Genus Sulfobacillus

The genus Sulfobacillus includes moderately thermophilic and thermotolerant acidophilic bacteria, which prefer mixotrophic growth conditions. These organisms are S. thermosulfidooxidans 1269Т, S. sibiricus N1Т and S. thermotolerans Kr1Т. The simultaneous presence of organic (for example yeast extract) and inorganic energy sources is essential for optimal growth. Carbon sources are both CO2 and organic compounds. During their mixotrophic growth, the basic pathways of carbohydrate catabolism of sulfobacilli are those of glycolysis, oxidative pentose phosphate and Entner–Doudorov (excepting strain N1). Assimilation of CO2 is carried out both auto- and heterotrophically. Final stages of oxidation of organic substances serve for cell biosynthesis. Bacteria are able to switch to organo- and autotrophic metabolism. At that the enzyme activities of pentose phosphate pathway are not detected. The cycle of tricarboxylic acids is disrupted at the level of 2-oxoglutarate dehydrogenase. The glyoxylate bypass is absent. The maximal protein and ATP values and high intensity of respiration in S. thermosulfidooxidans, S. sibiricus and S. thermotolerans cultures were determined under mixotrophic conditions. Studied strains due to their flexible carbon and energetic metabolism together with other microorganisms of communities (leptospirilli and archaea) participate in sulfide minerals processing at 40-450C without organic compounds supplement.

Glucose catabolic pathways in Lentinula edodes determined with radiorespirometry and enzymic analysis

Carbohydrate metabolism in different tissues was studied using radiorespirometry and enzymic analysis. The 14 C-1/ 14 C-6 ratios in CO 2 respired from specifically labelled glucose fed to Lentinula edodes tissues grown on a chemically defined medium ranged from 2·5 (vegetative mycelium) to 14·9 (young lamellae). This reflects the relative activity of the pentose phosphate pathway (PPP), very high in basidiome but low in mycelium, the highest ratio being recorded in tissues which are biosynthetically most active (young lamellae), requiring the reducing power of NADPH generated through the PPP. Extensive conversion of 14 C-3, 4-labelled glucose to 14 CO 2 in the mycelium underlined the important role of the Embden-Meyerhof-Parnas pathway (EMP) in that tissue. A 14 C-1/ 14 C-6 ratio of 14·8 for young lamellae grown on woodchips indicates that the growth medium did not influence the pathway used in the basidiome. Ratios for the young pileipellis and stipe were 8·0 and 10·4 respectively. A ratio of 3·6 for Coprinus cinereus gills confirms the comparatively lesser importance of the PPP in this organism. Enzymic determination corroborated the metabolic pattern deduced from radiolabelling. Activity of PPP enzymes (glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) were three times as high in the basidiome compared with the mycelium, highest activity being in the young pileus. EMP enzymes (fructose 1,6-bisphosphate aldolase and glucose 6-phosphate isomerase) were more active in mycelium than in fruit body, and also more active than PPP enzymes within the mycelium itself. Within the basidiome, specific activities of EMP and PPP enzymes were about the same. Enzymic activity in mature pileus of C. cinereus resembled the pattern in the mycelium rather than the basidiome of L. edodes ; EMP enzymes were very much more active than PPP. The positive correlation between high PPP activity and accumulation of large amounts of mannitol in the basidiome is discussed.