In an earlier report (1) we compared the responses of hepatic glycolytic enzyme activities of normal rats fed either glucose or fructose for 3 days. The enzymes studied were phosphoglucomutase, glucose 6-phosphatase, phosphoglucose isomerase, and the dehydrogenases of glucose B-phosphate and gluconate g-phosphate. When the diets containing free hexoses were substituted for the stock diet, the a...

The induction of the hexose-6-phosphate transport system was investigated. Glucose-6-phosphate (G6P) at concentrations as low as 10(-4)m was able to induce this system in wild-type cells, as well as in mutants lacking phosphoglucose isomerase or G6P dehydrogenase. Growth in the presence of fructose-6-phosphate (F6P) induced the system only if the cells contained phosphoglucose isomerase. Furthe...

The intracellular localization of transaldolase, transketolase, ribose-5-phosphate isomerase, and ribulose-5-phosphate epimerase was reexamined in spinach (Spinacia oleracea L.) leaves. We found highly predominant if not exclusive localization of these enzyme activities in chloroplasts isolated by isopyknic centrifugation in sucrose gradients. Glucose-6-phosphate dehydrogenase, 6-phosphoglucona...

catalytic isomerization of glucose to fructose by immobilized glucose isomerase in an aqueous-ethanol medium was studied. using michaelis-menten equation and haldane relationship, the main kinetic parameters were determined: kmf, vmf, kmr, vmr. by comparing the aqueous-ethanol medium with an aqueous solution, the measured values of kmr and kmf were increased in the aqueous-ethanol solution, whi...

Cryptosporidium parvum is one of several Cryptosporidium spp. that cause the parasitic infection cryptosporidiosis. Cryptosporidiosis is a diarrheal infection that is spread via the fecal-oral route and is commonly caused by contaminated drinking water. Triosephosphate isomerase is an enzyme that is ubiquitous to all organisms that perform glycolysis. Triosephosphate isomerase catalyzes the for...

BACKGROUND Ethanolic fermentation of lignocellulosic biomass is a sustainable option for the production of bioethanol. This process would greatly benefit from recombinant Saccharomyces cerevisiae strains also able to ferment, besides the hexose sugar fraction, the pentose sugars, arabinose and xylose. Different pathways can be introduced in S. cerevisiae to provide arabinose and xylose utilisat...

Glucose isomerase from Streptomyces rubiginosus was crystallized in two forms: I222, with one molecule of 44 kDa in the asymmetric unit, and P2(1)2(1)2, with two unique molecules. The I222 structure is known, but the P2(1)2(1)2 form has not been solved before. X-ray diffraction data for the P2(1)2(1)2 form were collected at a wavelength of 1.54 A and data for the I222 form were collected at thr...

The Zymomonas mobilis gene encoding phosphoglucose isomerase (pgi) was cloned by genetic complementation of an Escherichia coli pgi mutant. An enzyme assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirmed the presence of excess amounts of phosphoglucose isomerase in E. coli clones carrying the Z. mobilis pgi gene. The pgi gene is present in only one copy on the Z. mobilis...

Streptomyces sp. CH7 was found to efficiently produce glucose(xylose) isomerase when grown on either xylan or agricultural residues. This strain produced a glucose(xylose) isomerase activity of roughly 1.8 U/mg of protein when it was grown in medium containing 1% xylose as a carbon source. Maximal enzymatic activities of about 5 and 3 U/mg were obtained when 1% xylan and 2.5% corn husks were us...

Catalytic isomerization of glucose to fructose by immobilized glucose isomerase in an aqueous-ethanol medium was studied. Using Michaelis-Menten equation and Haldane relationship, the main kinetic parameters were determined: Kmf, Vmf, Kmr, Vmr. By comparing the aqueous-ethanol medium with an aqueous solution, the measured values of Kmr and Kmf were increased in the aqueous-ethanol solution, whi...