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Catalytic Specificity (catalytic + specificity)
Selected AbstractsCandida antarctica Lipase B (CAL-B)-Catalyzed Carbon-Sulfur Bond Addition and Controllable Selectivity in Organic MediaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2008Feng-Wen Lou Abstract A novel enzymatic, promiscuous protocol for Candida antarctica lipase B (CAL-B)-catalyzed carbon-sulfur bond addition is described. Some control experiments have been designed to demonstrate the catalytic specificity of CAL-B. Selectivity between anti-Markovnikov addition and Markovnikov addition was achieved in different organic media. A series of thioether-containing ester functional groups was synthesized under the catalysis of CAL-B at 50,°C. All the products were characterized by spectroscopic methods (IR, NMR, ESI-MS). [source] Promiscuous Acylases-Catalyzed Markovnikov Addition of N-Heterocycles to Vinyl Esters in Organic MediaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4-5 2006Wei-Bo Wu Abstract Three acylases, including D -aminoacylase from Escherichia coli, acylase "Amano" from Aspergillus oryzae and immobilized penicillin G acylase from Escherichia coli have been found to possess novel activity to catalyze the Markovnikov addition reaction of N-heterocycles to vinyl esters. The aza-Markovnikov addition reactions of 4-nitroimidazle to vinyl acetate catalyzed by D -aminoacylase, acylase "Amano" and immobilized penicillin G acylase were up to 1260-fold, 720-fold and 320-fold faster than the respective non-enzymatic reaction. Some control experiments have been designed to demonstrate the catalytic specificity of acylases. Under the catalysis of these promiscuous acylases, a number of N-heterocycles, including some pentacyclic N-heterocycles, pyrimidines and purines, were successfully added to a series of vinyl esters in moderate to excellent yields to prepare N-heterocycle derivatives. The acylase-catalyzed Markovnikov addition reaction has provided a new strategy to perform the Markovnikov addition and expanded the application of biocatalysts. [source] An efficient algorithm for multistate protein design based on FASTERJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 5 2010Benjamin D. Allen Abstract Most of the methods that have been developed for computational protein design involve the selection of side-chain conformations in the context of a single, fixed main-chain structure. In contrast, multistate design (MSD) methods allow sequence selection to be driven by the energetic contributions of multiple structural or chemical states simultaneously. This methodology is expected to be useful when the design target is an ensemble of related states rather than a single structure, or when a protein sequence must assume several distinct conformations to function. MSD can also be used with explicit negative design to suggest sequences with altered structural, binding, or catalytic specificity. We report implementation details of an efficient multistate design optimization algorithm based on FASTER (MSD-FASTER). We subjected the algorithm to a battery of computational tests and found it to be generally applicable to various multistate design problems; designs with a large number of states and many designed positions are completely feasible. A direct comparison of MSD-FASTER and multistate design Monte Carlo indicated that MSD-FASTER discovers low-energy sequences much more consistently. MSD-FASTER likely performs better because amino acid substitutions are chosen on an energetic basis rather than randomly, and because multiple substitutions are applied together. Through its greater efficiency, MSD-FASTER should allow protein designers to test experimentally better-scoring sequences, and thus accelerate progress in the development of improved scoring functions and models for computational protein design. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Promoting ,-secretase cleavage of beta-amyloid with engineered proteolytic antibody fragmentsBIOTECHNOLOGY PROGRESS, Issue 4 2009Srinath Kasturirangan Abstract Deposition of beta-amyloid (A,) is considered as an important early event in the pathogenesis of Alzheimer's Disease (AD), and reduction of A, levels by various therapeutic approaches is actively being pursued. A potentially non-inflammatory approach to facilitate clearance and reduce toxicity is to hydrolyze A, at its ,-secretase site. We have previously identified a light chain fragment, mk18, with ,-secretase-like catalytic activity, producing the 1,16 and 17,40 amino acid fragments of A,40 as primary products, although hydrolysis is also observed following other lysine and arginine residues. To improve the specific activity of the recombinant antibody by affinity maturation, we constructed a single chain variable fragment (scFv) library containing a randomized CDR3 heavy chain region. A biotinylated covalently reactive analog mimicking ,-secretase site cleavage was synthesized, immobilized on streptavidin beads, and used to select yeast surface expressed scFvs with increased specificity for A,. After two rounds of selection against the analog, yeast cells were individually screened for proteolytic activity towards an internally quenched fluorogenic substrate that contains the ,-secretase site of A,. From 750 clones screened, the two clones with the highest increase in proteolytic activity compared to the parent mk18 were selected for further study. Kinetic analyses using purified soluble scFvs showed a 3- and 6-fold increase in catalytic activity (kcat/KM) toward the synthetic A, substrate compared to the original scFv primarily due to an expected decrease in KM rather than an increase in kcat. This affinity maturation strategy can be used to select for scFvs with increased catalytic specificity for A,. These proteolytic scFvs have potential therapeutic applications for AD by decreasing soluble A, levels in vivo. © 2009 American Institute of Chemical Engineers. Biotechnol. Prog., 2009 [source] | ||||||||||