Esterase

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

The EstA esterase is responsible for the main capacity of Lactococcus lactis to synthesize short chain fatty acid esters in vitro.

Abstract: Aims: Esters of short-chain fatty acids and alcohols participate significantly in the overall flavour of foods. The capacity of the lactic acid bacterium Lactococcus lactis to synthesize such esters is known even though the enzymes involved in the process are not well identified. The objective of our work is to determine whether the esterase is responsible for the whole capacity of L. lactis to synthesize esters in vitro. Methods and Results: A negative mutant for the esterase was constructed and its capacity to synthesize short chain fatty acid esters from different substrate couples was compared to that of the wild type. We observed that the esterase is responsible for the main ester synthesis activity of L. lactis in vitro. However, in the presence of some substrates, the esterase negative mutant still synthesizes low amounts of esters. Conclusions: In favourable environmental conditions, the L. lactis esterase is responsible for the main ester synthesizing activity, even though another pathway for ester synthesis probably exists. Significance and Impact of the Study: Since esters are potent aroma compounds, esterase is probably a key enzyme in the development of food flavour.

A novel cold-adapted and highly salt-tolerant esterase from Alkalibacterium sp. SL3 from the sediment of a soda lake.

Abstract: A novel esterase gene (estSL3) was cloned from the Alkalibacterium sp. SL3, which was isolated from the sediment of soda lake Dabusu. The 636-bp full-length gene encodes a polypeptide of 211 amino acid residues that is closely related with putative GDSL family lipases from Alkalibacterium and Enterococcus. The gene was successfully expressed in E. coli and the recombinant protein (rEstSL3) was purified to electrophoretic homogeneity and characterized. rEstSL3 exhibited the highest activity towards pNP-acetate and had no activity towards pNP-esters with acyl chains longer than C8. The enzyme was highly cold-adapted, showing an apparent temperature optimum of 30 °C and remaining approximately 70% of the activity at 0 °C. It was active and stable over the pH range from 7 to 10 and highly salt-tolerant up to 5 M NaCl. Moreover, rEstSL3 was strongly resistant to most tested metal ions, chemical reagents, detergents and organic solvents. Amino acid composition analysis indicated that EstSL3 had fewer proline residues, hydrogen bonds and salt bridges than mesophilic and thermophilic counterparts, but more acidic amino acids and less hydrophobic amino acids when compared with other salt-tolerant esterases. The cold active, salt-tolerant and chemical-resistant properties make it a promising enzyme for basic research and industrial applications.

Screening of Nonfilamentous Bacteria for Production of Cutin-Degrading Enzymes

Abstract: Two hundred thirty-two nonfilamentous bacterial strains, including saprophytes, plant pathogens, and opportunistic plant and human pathogens, were screened for the ability to produce cutinases (cutin-degrading esterases). Initially, esterase activity of culture filtrates of strains grown in nutrient broth-yeast extract medium supplemented with 0.4% apple or tomato cutin was determined by a spectrophotometric assay utilizing the model substrate p-nitrophenyl butyrate. The culture filtrates of the 10 Pseudomonas aeruginosa strains tested exhibited the highest esterase activity, with values of >500 nmol/min/ml. Of these 10 strains, 3 (K799, 1499A, and DAR41352) demonstrated significant induction (10-fold or above) of esterase activity by addition of cutin to nutrient broth-yeast extract medium. The ability of culture filtrates of the three strains to cause release of apple cutin monomers was confirmed by a novel high-performance liquid chromatography technique. Monomer identification was confirmed by gas chromatography-mass spectroscopy analyses. Addition of the nonionic detergent n-octylglucoside stimulated cutinase activity of culture filtrates from strains K799 and DAR41352, but not that of filtrates from strain 1499A. Time course studies in nutrient broth-yeast extract medium supplemented with apple cutin indicated maximal levels of cutinase in the culture fluids after cultures entered stationary phase. Incubation temperatures below the optimal temperature for growth (37°C) led to maximal production of cutinase.

Specificity of procaine and ester hydrolysis by human, minipig, and rat skin and liver.

Abstract: The capacity of human, minipig, and rat skin and liver subcellular fractions to hydrolyze the anesthetic ester procaine was compared with carboxylesterase substrates 4-methylumbelliferyl-acetate, phenylvalerate, and para-nitrophenylacetate and the arylesterase substrate phenylacetate. Rates of procaine hydrolysis by minipig and human skin microsomal and cytosolic fractions were similar, with rat displaying higher activity. Loperamide inhibited procaine hydrolysis by human skin, suggesting involvement of human carboxylesterase hCE2. The esterase activity and inhibition profiles in the skin were similar for minipig and human, whereas rat had a higher capacity to metabolize esters and a different inhibition profile. Minipig and human liver and skin esterase activity was inhibited principally by paraoxon and bis-nitrophenyl phosphate, classical carboxylesterase inhibitors. Rat skin and liver esterase activity was inhibited additionally by phenylmethylsulfonyl fluoride and the arylesterase inhibitor mercuric chloride, indicating a different esterase profile. These results have highlighted the potential of skin to hydrolyze procaine following topical application, which possibly limits its pharmacological effect. Skin from minipig used as an animal model for assessing transdermal drug preparations had similar capacity to hydrolyze esters to human skin.