Search results for "terase"

Cyclodextrins in Polymer Synthesis: Synthesis and Influence of Methylatedβ-Cyclodextrin on the Radical Polymerization Behavior of 1,1-Disubstituted 2…

2001

The chemical and enzymatic hydrolyses of 1,1-diethoxycarbonyl-2-vinylcyclopropane (1) were investigated. The product of the pig liver esterase (PLE)-catalyzed hydrolysis of 1 is a chiral trans monoester of 2-vinylcyclopropane dicarboxylic acid. New 1,1-disubstituted 2-vinylcyclopropane monomers (2a, b) were synthesized by the esterification of this ester. Methylated β-cyclodextrin was used to complex monomers 2a, b, yielding water-soluble 1 : 1 host/guest complexes. These complexes were polymerized in aqueous media by a free-radical ring-opening mechanism.

Influence of Several Effectors on the Structure-Activity Relationship of Spleen Phosphodiesterase

1993

The influence of Mg(II) and organic solvents on the structure-activity relationship of spleen phosphodiesterase II was analyzed using UV and fluorescence spectroscopies. An increase in the RNase activity found in the presence of Mg(II) was related to the enzyme-Mg(II) interaction detected by UV spectroscopy. In the fluorescence spectra of phosphodiesterase strong hypochromic and bathochromic effects were observed when RNA was present at a concentration (52 μg ml−1) of the same magnitude as the concentration that inhibits the activity (Ki = 40 μg ml−1). The strong quenching observed in the presence of RNA shows the importance of large dynamic and static quenching of the Trp residues of the e…

Pig liver esterase (PLE)-mediated resolution of N-substituted 4-benzoyloxy-3-carbomethoxypiperidines: A convenient preparation of 4-hydroxy- and 4-be…

2000

Abstract Pig liver esterase (PLE) afforded smooth chemical resolution of racemic N -substituted 4-(benzoyloxy)-3-carbomethoxypiperidines. The enzyme showed good chemo- and enantioselective properties, thus allowing discrimination between the carbomethoxy and benzoate ester groups, the latter being more easily hydrolyzed. The proposed methodology also represents a practical means for the procurement of N -substituted 4-hydroxy-3-carbomethoxypiperidines in enantiomerically pure form.

Chapter 17: The cholinesterases: a discussion of some unanswered questions

1993

Publisher Summary During the past three decades, a vast body of specificity and kinetic data relating to the cholinesterases has accumulated, which must now be explained by the extremely interesting new sequence and X-ray crystallographic results presented by MassouliC et al. As this chapter shows, the cholinesterases are remarkable among enzymes in having a broad specificity embracing both charged and uncharged substrates but with a clearly expressed preference, at any rate in the aliphatic series, for the acylcholine configuration: a classical example of the principle of complementariness between substrate and active site as the basis for enzyme action. It is well known that AChE exists i…

Chemie an starren Grenzflächen, 10. Kinetisches Verhalten einiger an „Isothiocyanato-Aerosil” immobilisierter Esterasen – Analogversuche mit Insulin

1988

Amino-Aerosil wird mit Thiophosgen nach Gl. (1) in Isothiocyanato-Aerosil 2 (NCS-Aerosil) ubergefuhrt. Trypsin, Cholinesterase und Acetylcholinesterase werden an 2 nach Gl. (2) immobilisiert. Die Aktivitat der immobilisierten Esterasen wird untersucht auf (a) Lagerstabilitat, (b) Temperaturbestandigkeit und (c) pH-Abhangigkeit. Das kinetische Verhalten der immobilisierten Enzyme wird verglichen mit dem der freien, aber mit n-Butylisothiocyanat behandelten Esterasen. Am Beispiel der Cholinesterase, die uber unterschiedliche Ankergruppen mit Aerosil verknupft wurde, wird der Einflus unterschiedlicher Spacergruppen auf die Hydrolysegeschwindigkeit studiert. Aerosile, die mit Acetylcholin-Analo…

Acetylcholine esterase: the structure.

1991

Biochemical Characterization of an Acetylcholine-hydrolyzing Enzyme from Bean Seedlings.

1980

An acetylcholine hydrolyzing enzyme was prepared and purified (40 times) from dwarf bean hypocotyl hooks. The purity of the enzyme was proved by polyacrylamide gel electrophoresis. The molecular weight of the enzyme was determined to be 65,000 daltons. Enzyme activity was the highest at pH 8.0 and between 30 and 36 C. The enzyme had an apparent affinity constant (K(m)) for acetylcholine of 460/micromolar. The affinity for substrate analogs increased from butyrylthiocholine to propionylthiocholine to acetylthiocholine. The enzyme activity was inhibited by choline, neostigmine, physostigmine, manganese, and calcium. Magnesium had no influence on the enzyme activity. We conclude that the enzym…

Cell wall-degrading enzymes produced in vitro by isolates of Phaeosphaeria nodorum differing in aggressiveness

2000

The relationships between in vitro production of cell wall-degrading enzymes and aggressiveness of three Phaeosphaeria nodorum isolates were investigated. When grown in liquid medium containing 1% cell wall from wheat leaves as the carbon source, the isolates secreted xylanase, α-arabinosidase, β-xylosidase, polygalacturonase, β-galactosidase, cellulase, β-1,3-glucanase, β-glucosidase, acetyl esterase and butyrate esterase. Time-course experiments showed different levels of enzyme production and different kinetics between isolates. A highly aggressive isolate produced more xylanase, cellulase, polygalacturonase and butyrate esterase than did the two weakly aggressive isolates. Xylanase was …

The gene encoding polyneuridine aldehyde esterase of monoterpenoid indole alkaloid biosynthesis in plants is an ortholog of theα/β hydrolase super fa…

2000

The biosynthesis of the anti-arrhythmic alkaloid ajmaline is catalysed by more than 10 specific enzymes. In this multistep process polyneuridine aldehyde esterase (PNAE) catalyses a central reaction by transforming polyneuridine aldehyde into epi-vellosimine, which is the immediate precursor for the synthesis of the ajmalane skeleton. PNAE was purified from cell suspension cultures of Rauvolfia serpentina. The N-terminal sequence and endoproteinase LysC fragments of the purified protein were used for primer design and for the amplification of specific PCR products leading to the isolation of PNAE-encoding cDNA from a R. serpentina library. The PNAE cDNA was fused with a C-terminal His-tag, …

Differential behaviour of Pseudomonas sp. 42A2 LipC, a lipase showing greater versatility than its counterpart LipA

2009

Abstract Growth of Pseudomonas sp. 42A2 on oleic acid releases polymerized hydroxy-fatty acids as a result of several enzymatic conversions that could involve one or more lipases. To test this hypothesis, the lipolytic system of strain Pseudomonas sp. 42A2 was analyzed, revealing the presence of at least an intracellular carboxylesterase and a secreted lipase. Consensus primers derived from a conserved region of bacterial lipase subfamilies I.1 and I.2 allowed isolation of two secreted lipase genes, lipA and lipC, highly homologous to those of Pseudomonas aeruginosa PAO1. Homologous cloning of the isolated lipA and lipC genes was performed in Pseudomonas sp. 42A2 for LipA and LipC over-expr…