The maleylpyruvate isomerase NagL from Ralstonia sp. strain U2, which has been structurally characterized previously, catalyzes the isomerization of maleylpyruvate to fumarylpyruvate. It belongs to the class zeta glutathione S-transferases (GSTZs), part of the cytosolic GST family (cGSTs). In this study, site-directed mutagenesis was conducted to probe the functions of 13 putative active site r...

By L. G. ISIIAELS, G. E. DELORY, L. HNATIUK AND E. FRIESEN T HE SERUM activity of phosphohexose isonsserase, the enszyme faeilitatinsg the coisversions of glucose-6-phosphate to fructose-6-plsosphate, has recetstly conse insto use as an inidex of tumor growth and nsetastatic disease. Bodanssky was able to demonsstrate increased serum isomerase activity ins nsetastatic carcinsonsa of breast amsd...

The effect of several dose levels of estradici valerate on the activities of 6 enzymes and the levels of nucleic acids and certain lipids was studied in a transplantable lactating mammary adenocarcinoma, R3230AC, as well as in the mammary glands of the same tumor-bearing animals. Estrogen treatment caused a doserelated increa.se in the activities of glucose-6-phosphate dehydrogenase, malate deh...

This transformation is intramolecular and would involve no exchange between the migratory hydrogen and hydrogen in the aqueous solvent. (2) The hydrogen may migrate as a proton (Fig. l), in which case exchange with the solvent would occur. In order to distinguish between these alternatives the conversion of fructose-6-phosphate (F-6-P) into glucose-6phosphate (G-6-P)) catalyzed by phosphoglucos...

The heterologous expression of a highly functional xylose isomerase pathway in Saccharomyces cerevisiae would have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways in S. cerevisiae suffer from poor ethanol productivity, low xylose consum...

The teleost Fundulus heteroclitus (L.) possesses two loci, Gpi-A and Gpi-B, for the glycolytic enzyme, glucose-phosphate isomerase (GPI; D-glucose-6-phosphate ketol-isomerase; E.C. 5.3.1.9). The Gpi-B locus is polymorphic in Fundulus, with two common alleles, Gpi-Bb and Gpi-Bc, distributed in a clinal manner in populations along the east coast of North America. Since this clinal distribution is...

Phosphoglucose isomerase (PGI) allozymes were isolated from the wing-polymorphic water strider, Limnoporus canaliculatus, and were characterized biochemically with respect to temperature-dependent kinetic and thermostability properties. At higher temperatures, the allozymes exhibited significant differences in Michaelis constant (Km) values for substrates of both the forward and reverse reactio...

In order to assess the roles of specific amino acid residues in the delta 5-3-ketosteroid isomerase from Pseudomonas putida biotype B during catalysis, we replaced aspartic acid 40 with asparagine (D40N) and tyrosine 16 with phenylalanine (Y16F) in the enzyme by site-directed mutagenesis. Both purified mutant enzymes resulted in profound decreases in catalytic activities, 10(3.3)-fold in the Y1...

The interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate catalyzed by the enzyme triosephosphate isomerase was first demonstrated by Meyerhof and Kiessling (1). Since then studies with the enzyme have disclosed little about the mechanism of this reaction. Such an interconversion may be envisioned as occurring by formation of an enediol as, based on chemical analogy (2)) ...

BACKGROUND Xylose isomerase (XI) catalyzes the conversion of xylose to xylulose, which is the key step for anaerobic ethanolic fermentation of xylose. Very few bacterial XIs can function actively in Saccharomyces cerevisiae. Here, we illustrate a group of XIs that would function for xylose fermentation in S. cerevisiae through phylogenetic analysis, recombinant yeast strain construction, and xy...