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Showing 1 to 20 of 253 for “"transition state"”.
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Development of transition state analogues targeting chitinases and oligosaccharyl transferase
… pathways, they are believed to share similar transition states involving an oxocarbenium ion. To understand the mechanism of OT and discover potent and selective inhibitors against different chitinases, our intent was to utilize the common transition state analogue for both enzymes and …
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Mechanistic Investigations of Taxadiene Biosynthesis Using Substrate and Transition State Analogs
Additionally, 2-fluoroGGPP was synthesized as an inert substrate analog in crystallization of TS and as an active site probe in X-ray crystallography.
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Synthesis and Claisen Rearrangement of Alpha-Ethoxyallyl Vinyl Ethers. Evidence for a Dipolar Transition State
The product stereoselectivity, scope, and mechanism of the Claisen-Micheal reaction (8 $\rightarrow$ 11) were explored. The products (e.g. 11) of the Claisen-Micheal reaction, which are enol ethers, are protected equivalents of the adducts obtained from the Micheal reaction of $\alpha,\beta$-enals …
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Investigations into the mechanism of orotidine 5'-monophosphate decarboxylase: Sources of substrate destabilization and transition state stabilization
… analogues were used to investigate possible transition state stabilization by a carbene resonance structure. Viability of the carbene structure depends upon a key hydrogen bond between O4 of the substrate and the amide backbone of a conserved serine or threonine. Substitution of the conserved …
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Assessing the transition state model for cellular differentiation in vivo: a case study of zebrafish neuromesodermal progenitors
… or progenitor cells undergo a sequence of cell state changes before acquiring the characteristics of their destination fate. The transition state model proposes that a transient window of increased gene expression stochasticity and diversity precedes the coherent entry into the differentiated …
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Investigations of transition state geometry in the intramolecular aldol reaction and the intramolecular reaction of allylsilanes with aldehydes
Investigations into factors which influence the transition state geometry of the aldol reaction are described. Synthesis of two bicyclic model systems designed to study base-catalyzed intramolecular aldol reactions are reported, along with the effects that various metal counterions, solvents, and …
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Investigating the role of information technology in resolving governance challenges in a transition state - the case of Tanzania
… and practitioners and more so for the transition economies which are characterised by weak institutions, insecurity, political instability and poor IT skills and capabilities. Limited studies have been conducted to examine this problem in transition states in Africa. The objective of …
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Hydrolytic cleavage of p-nitrophenyl esters of N-protected amino acids in the presence of cyclodextrins : transition state stabilization
… the extent to which the three stabilize the transition states of the normal ester cleavage reactions was estimated, and used to probe the structures of the transition state complexes. Cleavage of the p-nitrophenyl esters of BOC-Asn, CBZ-Asn, BOC-Gln, and CBZ-Gln in basic aqueous solution …
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Part I. Chemical Theory and Emf Studies of Highly Solvated Liquid Metal Systems. Part Ii. The Compressibility of The Chemical Reaction Transition State
Made available in DSpace on 2014-12-13T18:55:30Z (GMT). No. of bitstreams: 1 7606965.pdf: 7509509 bytes, checksum: bb4a12e09b36c4ed634412e16f88a4db (MD5) Previous issue date: 1975
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1-Acylamido boronic acids and Difluoroborane analogs of amino acids: Synthesis and biological activity of transition state analogs for Chymotrypsin and Elastase (inhibition, esters)
… have been synthesized and evaluated as ""transition state"" inhibitors of the serine proteases (alpha)-chymotrypsin and elastase. These inhibitors were designed to resemble N-acyl phenylalanine, phenylglycine (as chymotrypsin inhibitors), alanine, valine, and isoleucine (as elastase …
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A Computational Analysis of Supported and Unsupported Group 6 Transition Metal-Metal Bonds Based on the Natural Orbitals for Chemical Valence (NOCV) and the Extended Transition State (ETS) Techniques
… on the nature of the metal-metal bond of group 6 transition metal complexes based on the extended transition state (ETS) and natural orbitals for chemical valence (NOCV) methods. The analysis of the unsupported triple (M2L6) and quadruple (M2L2L´2; M=Cr,Mo,W; L,L´=π-acceptor/σ-donor ligands) …
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Probing static disorder in protein unfolding and chemical reactions by single-molecule force spectroscopy
… governs the reaction. The widely accepted two-state kinetic model for protein unfolding describes that the protein unfolds by crossing over a single energy barrier, with the implicit assumption of a single transition state and a well-defined activation energy barrier. Based on this assumption, …
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Substituted aryl glycosides as probes of the mechanism of spontaneous ad enzyme-catalyzed glycoside hydrolysis
… of the oxocarbonium ions generated at the transition state, which appear to be principally a function of field effects (as predicted by the Kirkwood-Westheimer hypothesis) exerted by the ring substituents at 05 and Cl. Differences in the rates of hydrolysis between different series of …
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1. The Endocyclic Restriction Test: Oxygen Transfer From N-Sulfonyl Oxaziridines to Alkenes and Fluorine From N-Fluorosultams to Carbanions. 2. Intra- and Intermolecular Kinetic Isotope Effects in Directed Lithiations
The transition state geometry for the transfer of oxygen from N-sulfonyl oxaziridines to alkenes and fluorine transfer from N-fluoro sultams to carbanions was investigated. In the former application of the endocyclic restriction test, a transition state model was developed, however, a model has not …
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Stabilization of transition states of organic reactions by cyclodextrins, micelles, and dendrimers
… linear correlation between the substrate and the transition state binding for different acetals and orthoesters, which reflects the importance of both nature of the substituent, and its location in the molecule of the substrate. Amino- and carboxylate-terminated dendrimers modestly catalyze the …
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Spectroscopic signatures of isomnerization
… of the potential energy surface, such as the transition state. The most important new pattern discovered is the "isomerization dip", a sharp decrease in the vibrational level spacings, or effective frequency, in modes that project along the reaction coordinate as the transition state is …
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A STUDY OF ENDOCYCLIC NUCLEOPHILIC SUBSTITUTION AT SULFUR(VI) (SULFONATE ESTERS)
… involving a four-membered cyclic intermediate or transition state, the reaction of N-methyl-N-phenyl-4-toluenesulfonamide with n-butyllithium, proved to be intramolecular. Another case involving a five-membered cyclic intermediate or transition state, the reaction of 2-aminoaryl arenesulfonates …
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Synthesis of Bulky and Polar Galactonoamidines for the Inhibition of the Human α-Galactosidase
… that enzymes bind to their substrate at the transition state with very strong affinity. Wolfenden estimated the dissociation constant to be around 10-22M. This encouraged the design of glycosidase inhibitors which mimicked one or more features of the transition state. The notable features of …
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