Esterase

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

Functional expression of a thermophilic glucuronoyl esterase from Sporotrichum thermophile : identification of the nucleophilic serine

Abstract: A glucuronoyl esterase (GE) from the thermophilic fungus Sporotrichum thermophile, belonging to the carbohydrate esterase family 15 (CE-15), was functionally expressed in the methylotrophic yeast Pichia pastoris. The putative GE gene ge2 from the genomic DNA was successfully cloned in frame with the sequence for the Saccharomyces cerevisiae α-factor secretion signal under the transcriptional control of the alcohol oxidase (AOX1) promoter and integrated in P. pastoris X-33 to confirm that the encoded enzyme StGE2 exhibits esterase activity. The enzyme was active on substrates containing glucuronic acid methyl ester, showing optimal activity at pH 7.0 and 55°C. The esterase displayed broad pH range stability between 4–10 and temperature stability up to 50°C, rendering StGE2 a strong candidate for future biotechnological applications that require robust biocatalysts. ClustalW alignment of StGE2 with characterized GEs and selected homologous sequences, members of CE-15 family, revealed a novel consensus sequence G-C-S-R-X-G that features the characteristic serine residue involved in the generally conserved catalytic mechanism of the esterase family. The putative serine has been mutated, and the corresponding enzyme has been expressed in P. pastoris to prove that the candidate nucleophilic residue is responsible for catalyzing the enzymatic reaction.

Synthesis and Enzymatic Hydrolysis of Esters, Constituting Simple Models of Soft Drugs

Abstract: One way to minimise systemic side effects of drugs is to design molecules, soft drugs, in such a way that they are metabolically inactivated rapidly after having acted on their pharmacological target. Hydrolases (esterases, peptidases, lipases, glycosidases, etc.) are enzymes well suited to use for drug inactivation since they are ubiquitously distributed. Insertion of ester bonds susceptible to enzymatic cleavage may represent one approach to make the action of a drug more restricted to the site of application. The present study describes the chemical synthesis of fourteen model compounds comprising a bicyclic aromatic unit connected by an ester-containing bridge to another aromatic ring. Initial attempts to define a) the tissue selectivity of the hydrolytic metabolism and b) the molecular structural factors affecting the rate of enzymatic ester cleavage are presented. The data show that human and rat liver fractions were more active than human duodenal mucosa and human blood leukocytes at hydrolysing the compounds. The rank order of the compounds was, however, very similar in the different biological systems. Commercially available pig liver carboxyl esterase and cholesterol esterase both reasonably well predict the rank order in the tissue fractions.

Genetic variation and geographic cline of esterase isozymes in native rice varieties

Abstract: Isozyme polymorphism of esterase in Oryza sativa L. was investigated with leaves of 776 native varieties collected from known sites of Asian countries by the use of horizontal agar gel thin layer electrophoresis.The esterase isozymes occurred in altogether fourteen all anodic bands. Of them, nine bands (1A, 2A, 6A, 7A, 10A, 11A, 12A, 13A, 14A) were easily distinguishable and their combination composed 27 different zymograms, indicating the presence of substantially complex variation. Each isozyme differed in its frequency of occurrence in each of the eight areas extended from Sri Lanka to Japan. The bands were grouped into two; one such as 1A and 11A occurred commonly through the areas, the other such as 6A, 7A, 12A and 13A occurred in a distinctive geographic cline.Zymogram patterns comprising the latter group's bands demonstrated a very conspicuous and sequential geographic cline, terminating in very simple zymograms at both south-and north-most areas of Asia. On the contrary, an area including Nepal, Bhutan, Assam, Burma, Vietnam and Yunnan of China was widest in variation of the zymogram patterns. Consequently, this area was postulated to be the center of genetic diversity in esterase isozymes of O. sativa, proposing an important working hypothesis in advancing researches on its speciation and migration.