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Biomedical subjects

A Datta

Publications and source records attributed to A Datta.

At least 145 records · Page 8Linked to original sources
PubMed1986

A cyclic AMP-independent protein kinase from Candida albicans.

A cyclic AMP-independent protein kinase which phosphorylates casein was purified to homogeneity from Candida albicans by affinity and ion-exchange chromatography. This protein kinase exhibits maximal activity with casein as substrate and is not stimulated by cyclic AMP or cyclic GMP. The Mr of the purified enzyme is 115,000, as determined by h.p.l.c. It migrates as a single band on gel electrophoresis and has three non-identical subunits, of Mr 44,000, 28,500 and 26,000, as determined by SDS/polyacrylamide-gel electrophoresis. This enzyme is insensitive to heparin, but is inhibited by polyamines. Furthermore, it is sensitive to thermal denaturation and to thiol reagents.

Candida albicans↗
PubMed1986

Immunochemical properties of the lipopolysaccharide O-antigen of Vibrio cholerae O1 in relation to its chemical structure.

D-Glucuronic acid and D-glucosamine have an immunodominant role in the lipopolysaccharide (LPS) O-antigen of both the Ogawa and the Inaba subtypes of Vibrio cholerae O1. This was evident from the pronounced inhibitory effect on the LPS precipitin reaction demonstrated by these monosaccharides and by oligosaccharides containing either of them which were isolated from LPS hydrolysate. There was a considerable decrease in the antibody-combining capacity of chemically modified LPS in which the carboxyl group of the glucuronic acid had been reduced. Similarly, on deamination, the O-specific polysaccharide fraction of the LPS molecule from both subtypes completely lost the ability to precipitate the LPS antibody.

Antigens, Bacterial↗
PubMed1985

Uterine changes on removal of submaxillary glands in rats (histological changes/uterine peroxidase/blood estradiol level).

Surgical removal of submaxillary gland in immature rats causes a large increase in size and about three to four fold increase in dry and wet weight of uterus compared to that of the sham operated animals of the same age group. Histological examination reveals a significant increase in the diameter of the uterus with considerable elongation of the luminal epithelium from cubical to columnar in the experimental group. Biochemical studies show that the uterine peroxidase (donor: hydrogen-peroxide oxidoreductase, EC 1.11.1.7), a marker enzyme for uterine growth, increases by ten to fifteen fold on submaxillariectomy and returns almost to the normal level on administration of submaxillary gland extract (105,000 X g supernatant) to the submaxillariectomized animals. Estrogen estimation by radioimmunoassay shows a similar increase of three to four fold on removal of submaxillary glands and decrease almost to the normal value on administration of the submaxillary extract.

Animals↗
PubMed1985

Substrate channeling of oxalacetate in solid-state complexes of malate dehydrogenase and citrate synthase.

Current evidence suggests that mitochondrial matrix enzymes exist in solid-state, multienzyme complexes in vivo. Addition of polyethylene glycol to a solution containing malate dehydrogenase and citrate synthase generates such a solid-state, enzyme complex in vitro at enzyme concentrations permitting kinetic measurements. Suspensions of the isolated, solid-state, hetero-complex of these enzymes were used to study the coupled reactions of citrate synthesis from malate, NAD, and CoASAc. The particles appear to be about 1 microgram in diameter. Considering the ratio of enzyme to oxalacetate molecules in or at the surface of the solid-state particles, one would expect oxalacetate to be converted to citrate within a few molecular distances of the site of oxalacetate generation. This model of "substrate channeling" (or alternatively a direct transfer of oxalacetate between enzymes) is supported by experiments with excess aspartate aminotransferase and glutamate added to the solution phase to give a reaction competing with the synthase for bulk phase oxalacetate. Quantities of aminotransferase that reduce the citrate reaction rate with soluble dehydrogenase and synthase by 90% do not significantly affect rates with comparable amounts of the dehydrogenase-synthase complex. We suggest that similar substrate channeling can occur in vivo and discuss the possible advantages provided thereby.

Animals↗
PubMed1985

Steroid binding protein(s) in yeasts.

A progesterone binding protein has been detected in the cytosol prepared from glucose grown cells of both Candida albicans and Saccharomyces cerevisiae. The specific activity of this binding protein is much higher in C. albicans, a pathogenic yeast as compared to the non-pathogenic yeast S. cerevisiae.

Alpha-Globulins↗
PubMed1984

Induction of N-acetyl-D-glucosamine catabolic enzymes and germinative response in Candida albicans.

The regulation of N-acetylglucosamine catabolic enzymes was studied in both yeast and germ tube forms of the dimorphic fungus Candida albicans. The induction pattern of these enzymes was the same for yeast cells incubated at 28 degrees C and in cells incubated at 37 degrees C which formed germ tubes. However, the level of activity of these enzymes in germ tube stage is lower as compared to yeast phase cells. A strain of C. albicans that did not form germ tubes was endowed with a pronounced ability for induction of N-acetylglucosamine catabolic enzymes. This result suggests that germ tube formation and N-acetylglucosamine metabolism are mutually exclusive events.

Acetylglucosamine↗
PubMed1983

Separation and partial characterization of smooth muscle contractile material in the venom of the scorpion Heterometrus bengalensis.

A smooth muscle contractile material was separated from crude venom of the scorpion Heterometrus bengalensis (found in Eastern India) by solvent extraction, gel filtration and thin layer chromatography. Smooth muscle contractile material could be extracted, in descending order of efficiency, with methanol, butanol, ethanol and acetone. The contractile material separated by gel filtration (Sephadex G-25) when further extracted, using the Folch procedure, showed a single spot in thin layer chromatography with one solvent system. Rechromatography of an eluate from this spot with another solvent system resolved it into three spots (SL1, SL2 and SL3, the mixture being designated as Substance L) which could be visualized either with iodine vapour, ninhydrin or molybdenum reagent. Eluates from the three spots contracted guinea-pig ileum which had been pretreated with antagonists of ACh, histamine, 5-HT and prostaglandins. Substance L and its fractions (SL1, SL2 and SL3) contain inorganic phosphorus, amino nitrogen and amino sugar, which point to the likelihood of their being glycophosphatides.

Animals↗
PubMed1982

Initiation of protein synthesis in eukaryotes. Nature of ternary complex dissociation factor.

Excessive concentrations of the eukaryotic initiation factor 2(eIF-2).stimulating protein, a factor that catalyzes the formation of binary (GTP.eIF-2) and ternary (GTP.eIF-2.initiator methionyl-tRNA) initiation complexes at physiological Mg2+ concentrations, can cause ternary complex dissociation when the Mg2+ concentration is raised from 0.5 to 5.0 mM. Stimulation of ternary complex formation and dissociation have similar (a) pH optima, (b) metal ion specificity, and (c) sensitivity to phosphorylation of the eIF-2 alpha subunit. The results suggest that ternary complex dissociation is an artifact with no physiological significance.

Animals↗