In this study, reactions of the simple cycloalkynes with substituted Nitrile Oxides, by DFT method will be discussed. The investigation of the structural properties, theoretical thermodynamic and kinetic data, i.e., the activation free energies(DG*), the free energies changes of reaction(DrG) and rate constants of the reactions (k) in 298 K and effects of Electron-withdrawing and...

Glycogen phosphorylase has been purified from rabbit liver by a simplified procedure which depends on the initial separation of the enzyme from a crude extract by centrifuging it as a complex with particulate glycogen. Initial rates have been measured with varied concentrations of both substrates in each reaction direction. The data were analyzed with double reciprocal plots and secondary plots...

Phosphotriesterase (PTE) from Pseudomonas diminuta is a zinc metalloenzyme that hydrolyzes a variety of organophosphorus compounds. The kinetic parameters of Zn/Zn PTE, Cd/Cd PTE, and a mixed-metal Zn/Cd hybrid PTE were obtained with a variety of substrates to determine the role of each metal ion in binding and catalysis. pH-rate profiles for the hydrolysis of diethyl p-nitrophenyl phosphate (I...

In this work, based on experimental observations and exact theoretical predictions, the kinetic scheme of RAFT polymerization is extended to a wider range of reactions such as irreversible intermediate radical terminations and reversible transfer reactions. The reactions which have been labeled as kinetic scheme are the more probable existing reactions as the theoretical point of view. The ...

This paper addresses, in thermodynamic and kinetic terms, the reasons for the acidic lipid specificity of the human prothrombinase complex. We obtained, from the measured lipid titrations of the initial rates of prothrombin activation, the empirical binding constants for prothrombinase assembly on different membranes. These favored assembly on phosphatidylserine (PS)- as opposed to phosphatidyl...

The endochitinase from barley is the archetypal enzyme for a large class of plant-derived antifungal chitinases. The X-ray structure was solved previously in our laboratory and a mechanism of action proposed based on structural considerations. In this manuscript we report the use of a defined soluble substrate, 4-methylumbelliferyl beta-N,N',N"-triacetylchitotrioside, to characterize kinetic pa...

The degradation of [5S-[5alpha,6beta,7alpha(R*)]]-2-butyl-5-(1,3-benzodioxol-5-yl)-7-[(2-carboxypropyl)-4-methoxyphenyl]-6-dihydro-5H-cyclopenta[b]pyridine-6-carboxylic acid (J-104,132) was studied in aqueous solution as a function of temperature and pH. The degradation reaction does not proceed to completion; rather, a stable equilibrium is attained in which approximately 2% of the degradate i...

A kinetic investigation into the origin of enantioselectivity for the Pd[(-)-sparteine]Cl(2)-catalyzed aerobic oxidative kinetic resolution (OKR) is reported. A mechanism to account for a newly discovered chloride dissociation from Pd[(-)-sparteine]Cl(2) prior to alcohol binding is proposed. The mechanism includes (1) chloride dissociation from Pd[(-)-sparteine]Cl(2) to form cationic Pd(-)-spar...

Esterification of lauric acid with n-butanol, catalyzed by immobilized Candida antarctica lipase (CAL) in aqueous-organic biphasic solvent system was studied. Effects of various reaction parameters on esterification were investigated, such as type and amount of solvent, amount of buffer, pH, temperature, speed of agitation, amount of enzyme, butanol and lauric acid. The most suitable reaction c...

Changes in the large neutral amino acid (LNAA) transport across the blood-brain barrier (BBB) is thought to contribute to brain dysfunction in a number of clinical conditions, including phenylketonuria, acute liver failure, and sepsis. Here, we present a novel approach for estimating BBB permeability and the LNAA concentrations in brain extracellular fluid, by demonstrating that they can be mat...