Synthèses enzymatiques de néoglucoconjugués catalysées par l'alpha-glucosidase purifiée de la blatte Periplaneta americana (Linnaeus)

Enzymatic synthesis of neoglucoconjugates by purified α-glucosidase from cockroach Periplaneta americana (Linnaeus). Cockroach Periplaneta americana (Linnaeus) contains in his digestive tract an acid (pH 5,0) and mesophile (50°C) α-glucosidase. This enzyme, purified to homogeneity, hydrolyses highly maltose, sucrose and p-nitrophenyl-α-Dglucopyranoside. The ability of α-glucosidase from cockroach purified to homogeneity to catalyse transglucosylation reactions was tested using maltose and saccharose as glucosyl donors and 2-phenylethanol and phenol as acceptors. The experimental conditions were optimized in relation to the time course of the reaction, pH and concentrations of glucosyl donors and acceptors. The yields in transglucosylation reactions at 37 °C were very high and could attain 67% and 48% with 2-phenylethanol and phenol respectively as glucosyl acceptors. This α-glucosidase hydrolyzed the products formed. It seems that the products formed were the phenylethyl-α-D-glucoside and phenyl-α-D-glucoside. These results suggest that α- glucosidase from cockroach is an exoglucosidase which catalyse the splitting of the α-glucosyl residue from the non reducing terminal of the substrate to liberate α-glucose. This comportment indicates that this enzyme operated by a mechanism involving the retention of the anomeric configuration. On the basis of this work, α-glucosidase from P. americana appears to be a valuable tool for the preparation of α-neoglucoconjugates

Purification and physicochemical properties of - amylase from cockroach, Periplaneta americana (LINNAEUS), for starches saccharification

An -amylase was purified from the American cockroach Periplaneta americana (Linnaeus) to homogeneity by four steps purification via ammonium sulphate crude extract precipitation, SephacrylS-100 HR gel permeation chromatography, anion exchange chromatography on DEAE-Sepharose CL-6B and hydrophobic interaction chromatography on phenyl Sepharose CL-4B. The purification was approximatively 38.42 fold with a 24.31% yield. Optimums pH and temperature of the purified -amylase were found to be 5.6 and 55°C, respectively. The enzyme was stable up to 55°C and its pH stability was in range of 5.6 - 6.6. The KM and Vmax of the enzyme with soluble starch as substrate were 5 mg/ml and100 ìmol/min/mg, respectively, and the energy of activation (Ea), was 50.32 Kj/mol. The -amylase was inhibited by Tris, Fe3+, Ba2+, Mo+ and EDTA. While Ca2+, K+, Cu2+, Mg2+ and  para-hydroxymercuribenzoate (pHMB) activated the enzyme. Analysis of the amylolytic reaction products by HPLC showed thepresence of maltose and maltodextrin but not glucose in the starch hydrolysate (2 h of reaction). This result indicated that the amylolytic enzyme of P. americana is an -amylase (an endoamylase). Thepurified -amylase hydrolysed maltopentose, maltohexose and maltoheptose. Maltose, maltotriose and maltotetrose were not hydrolysed by this enzyme. Therefore, the purified -amylase is active only on substrates with more than four residues of glucose

Recherche et étude comparative des activités protéasiques des castes neutres du termite Macrotermes subhyalinus (Termitidae, Macrotermitinae) et de son champignon symbiotique Termitomyces sp

Research and Comparative Study of Proteasic Activities of Neutral Castes of Termite Macrotermes subhyalinus (Termitidae, Macrotermitinae) and its Symbiotic Fungus Termitomyces sp. Crude extracts from neutral castes of the termite Macrotermes subhyalinus, its symbiotic fungus Termitomyces sp. and its comb are not able to hydrolyze acyl-pNA tested on acid medium. However, these substrates on alkaline medium are hydrolysed, indicating that these enzymatic sources possess proteolytic activities. Hydrolyzed acyl-pNA are Gly-pNA, LeupNA, Met-pNA, Phe-pNA, Pro-pNA, Lys-pNA, ArgpNA and Asp-pNA. The highest proteolytic activities were obtained with Leu-pNA and BA-pNA with a Macrotermes subhyalinus termite worker. It is therefore more active than the soldier. Proteolytic activities were higher in small soldiers than in large ones. The proteolytic activities of the fungus are higher than those of the fungus comb, its growth backbone. Mutal competition studies among the best hydrolysed substrates by symbiotic fungus and worker have shown that trypsic activities (Arg-pNA, Lys-pNA and BA-pNA) are derived from the same enzyme. This enzymatic reaction has also been observed with Leu-pNA, MetpNA and Ala-pNA

Interactions and potential implications of Plasmodium falciparum-hookworm coinfection in different age groups in south-central Côte d'Ivoire

BACKGROUND: Given the widespread distribution of Plasmodium and helminth infections, and similarities of ecological requirements for disease transmission, coinfection is a common phenomenon in sub-Saharan Africa and elsewhere in the tropics. Interactions of Plasmodium falciparum and soil-transmitted helminths, including immunological responses and clinical outcomes of the host, need further scientific inquiry. Understanding the complex interactions between these parasitic infections is of public health relevance considering that control measures targeting malaria and helminthiases are going to scale.METHODOLOGY: A cross-sectional survey was carried out in April 2010 in infants, young school-aged children, and young non-pregnant women in south-central Côte d'Ivoire. Stool, urine, and blood samples were collected and subjected to standardized, quality-controlled methods. Soil-transmitted helminth infections were identified and quantified in stool. Finger-prick blood samples were used to determine Plasmodium spp. infection, parasitemia, and hemoglobin concentrations. Iron, vitamin A, riboflavin, and inflammation status were measured in venous blood samples.PRINCIPAL FINDINGS: Multivariate regression analysis revealed specific association between infection and demographic, socioeconomic, host inflammatory and nutritional factors. Non-pregnant women infected with P. falciparum had significantly lower odds of hookworm infection, whilst a significant positive association was found between both parasitic infections in 6- to 8-year-old children. Coinfected children had lower odds of anemia and iron deficiency than their counterparts infected with P. falciparum alone.CONCLUSIONS/SIGNIFICANCE: Our findings suggest that interaction between P. falciparum and light-intensity hookworm infections vary with age and, in school-aged children, may benefit the host through preventing iron deficiency anemia. This observation warrants additional investigation to elucidate the mechanisms and consequences of coinfections, as this information could have important implications when implementing integrated control measures against malaria and helminthiases