Esterase

About: Esterase is a research topic. Over the lifetime, 7622 publications have been published within this topic receiving 168270 citations.

Enzymatic hydrolysis of esterified diarrhetic shellfish poisoning toxins and pectenotoxins

Abstract: Okadaic acid (OA) and dinophysistoxins-1 and -2 (DTX1, DTX2), the toxins responsible for incidents of diarrhetic shellfish poisoning (DSP), can occur as complex mixtures of ester derivatives in both plankton and shellfish. Alkaline hydrolysis is usually employed to release parent OA/DTX toxins, and analyses are conducted before and after hydrolysis to determine the concentrations of nonesterified and esterified toxins. Recent research has shown that other toxins, including pectenotoxins and spirolides, can also exist as esters in shellfish, but these toxins cannot survive alkaline hydrolysis. A promising alternative approach is enzymatic hydrolysis. In this study, two enzymatic methods were developed for the hydrolysis of 7-O-acyl esters, "DTX3," and the carboxylate esters of OA, "diol-esters." Porcine pancreatic lipase induced complete conversion of DTX3 to OA and DTXs within one hour for reference solutions. The presence of mussel tissue matrix reduced the rate of hydrolysis, but an optimized lipase concentration resulted in greater than 95% conversion within four hours. OA-diol-ester was hydrolyzed by porcine liver esterase and was completely converted to OA in less than 30 min, even in the presence of mussel tissue matrix. Esters and OA/DTX toxins were all monitoredbyLC-MS. Furtherexperimentswithpectenotoxin esters indicated that enzymatic hydrolysis could also be applied to esters of other toxins. Enzymatic hydrolysis has excellent potential as an alternative to the conventional alkaline hydrolysis procedure used in the preparation of shellfish samples for the analysis of toxins.

Characterization of the lipase activity of Malassezia furfur

Abstract: Enzymes capable of metabolizing lipids are essential for the growth of Malassezia furfur in vitro and in vivo. We designed a series of experiments to characterize the lipolytic system in this yeast. The optimal pH of the lipase system was 7.5 Lipase activity was detected in soluble and insoluble saline cell extracts and in supernatant from the cultures. Esterase activity screened in samples separated by native polyacrylamide gels showed that it was restricted to one band of low mobility. An FPLC analysis of the soluble saline extract demonstrated that the lipase activity was present in three major peaks with different protein composition as revealed by SDS-PAGE. The enzymatic activity and cell growth were first induced and later inhibited by increasing concentrations of polyethylene-sorbitan-monooleate (Tween-80). The characterization of the lipolytic system (e.g. its induction by substrate and the effect of pH and/or different cations) could help to explain the increment in the number of M. furfur infections related to alterations of surface lipids in the skin such as seborrheic dermatitis.

Biodegradation and Detoxification of Malathion by of Bacillus Thuringiensis MOS-5

Abstract: 3 Abstract: Efficiency of a strain of B. thuringiensis MOS-5 (Bt), isolated from agricultural waste water near Berket El-Sabaa Egypt contaminated with organophosphorus insecticide, for degradation of malathion was investigated. It was able to utilize malathion as a sole carbon and energy source and to degrade it cometabolically. In a minimal salt medium supplied with 250 mg 1 malathion ether alone -1 or incombination with glucose or yeast extract MOS-5 caused 99.32% reduction in malathion after 30 days. Addition of glucose (5 g l ) and yeast extract (0.5 g l ) increased the growth rate 10 and 10 fold, -1 -1 4 5 respectively, compared to malathion alone. Results of HPLC, gas chromatography/ mass spectrometry (GC/MS) and infrared spectroscopic analysis revealed that one malathion-derived compound mal-monocarboxylic acid (M MA) was producted after three days. Two additional malathion derivatives, mal-dicarboxylic acid (MDA) and unidentified mal-x were detected after 7 days. MMA and MDA were the major degrading compounds. Esterase activity involved in malathion degradation was also determined in culture filtrate of MOS-5. Results indicated that esterase activity was two folds more in the presence of yeast extract compared to glucose. These results indicate that Bt MOS-5 may consider as highly potential candidate in the biodegradation of organophosphorus in contaminated soil.