Entamoeba histolytica, heterologous expression and in situ immunolocalization of ornithine decarboxylase (EhODC).

Previous studies from this laboratory have dealt with the purification and biochemical characterization of ornithine decarboxylase (ODC) from Entamoeba histolytica. Enzyme compartmentalization has been described as a major mechanism in the regulation of polyamine metabolism. However, the subcellular location of ODC in the human parasite has remained unresolved.

Bursera fagaroides, effect of an ethanolic extract on ornithine decarboxylase (ODC) activity in vitro and on the growth of Entamoeba histolytica.

The effect of an ethanolic extract from the stem bark of Bursera fagaroides on ornithine decarboxylase (ODC) activity in vitro and on the growth of Entamoeba histolytica was evaluated. For this purpose, increasing concentrations of the extract, up to 8.0mg/mL, were added to amoeba cultures or ODC reaction mixtures, which were incubated at 37 degrees C.

Biosynthesis of glycoproteins in the pathogenic fungus Candida albicans: activation of dolichol phosphate mannose synthase by cAMP-mediated protein phosphorylation.

Following incubation with ATP and a cAMP-dependent protein kinase under optimal conditions of lipid acceptor, phospholipid and metal ion requirements, the transfer activity of partially purified dolichol phosphate mannose synthase (DPMS) increased about 60% and this activation correlated with a 50% increase in V(max) with no alteration in the apparent K(m) for GDP-Manose. Phosphorylation with [gamma-(32)P]ATP resulted in the labeling of several polypeptides, one of which exhibited the molecular weight of the enzyme (30 kDa) and was also recognized using a specific anti-DPMS monoclonal antibody. This and the fact that the phosphate label could be removed by an alkaline phosphatase indicate that Candida DPMS may be regulated by phosphorylation-dephosphorylation, a mechanism that has been proposed for the enzyme in other organisms.

Partial purification and biochemical characterization of a soluble alpha-glucosidase II-like activity from Candida albicans.

A soluble alpha-glucosidase was partially purified from Candida albicans cells by a three-step procedure consisting of size-exclusion, ion-exchange and adsorption chromatographies. After the last step, enzyme was enriched about 8.7-fold with a yield of 13% over the starting material and analysis of the purified preparation revealed two major polypeptides of 36 and 47 kDa.

Partial purification and characterization of a mannosyl transferase involved in O -linked mannosylation of glycoproteins in Candida albicans.

Incubation of a mixed membrane fraction of C. albicans with the nonionic detergents Nonidet P-40 or Lubrol solubilized a fraction that catalyzed the transfer of mannose either from endogenously generated or exogenously added dolichol-P-[14C]Man onto endogenous protein acceptors. The protein mannosyl transferase solubilized with Nonidet P-40 was partially purified by a single step of preparative nondenaturing electrophoresis and some of its properties were investigated.

Cr(VI) reduction in a chromate-resistant strain of Candida maltosa isolated from the leather industry.

A Cr(VI)-resistant yeast was isolated from tanning liquors from a leather factory in Leon, Guanajuato, Mexico. Based on morphological and physiological analyses and the D1/D2 domain sequence of the 26S rDNA, the yeast was identified as Candida maltosa. Resistance of the strain to high Cr(VI) concentrations and its ability to chemically reduce chromium was studied.

Purification and biochemical characterisation of a membrane-bound alpha-glucosidase from the parasite Entamoeba histolytica.

An alpha-glucosidase was solubilised from a mixed membrane fraction of Entamoeba histolytica and purified to homogeneity by a two-step procedure consisting of ion exchange chromatography in a Mono Q column and affinity chromatography in concanavalin A-sepharose. Although the enzyme failed to bind the lectin, this step rendered a homogenous and more stable enzyme preparation that resolved into a single polypeptide of 55 kDa after SDS-PAGE. As measured with 4-methylumbelliferyl-alpha-D-glucopyranoside (MUalphaGlc) as substrate, glycosidase activity was optimum at pH 6.

Purification and biochemical characterization of a soluble alpha-glucosidase from the parasite Entamoeba histolytica.

A soluble alpha-glucosidase presumably involved in the general carbohydrate metabolism was purified from E. histolytica trophozoites by a three-step procedure consisting of ion exchange, size exclusion and adsorption chromatographies in columns of Mono Q, Sepharose CL-6B and hydroxyapatite, respectively. After the last step, the enzyme was enriched about 673-fold over the starting material with a yield of 18%.

Entamoeba histolytica: purification and characterization of ornithine decarboxylase.

Ornithine decarboxylase, a rate-limiting enzyme in polyamine biosynthesis in eukaryotes, was stabilized and purified from trophozoites of the parasite protozoan E. histolytica. Analytical electrophoresis revealed the presence in the purified preparations of a major polypeptide of 45 kDa and barely detectable amounts of two other proteins of 70 and 120 kDa.