Herein, we present (E)-selective transfer semihydrogenation of alkynes based on an iridium complex in situ generated from [Ir(COD)Cl]2 and unsymmetrical (bearing two different phosphorous centers), ferrocene-based phosphine ligand utilizing formic acid as a hydrogen donor. Interestingly, ligand-to-metal ratio may be used to control the stereoselectivity process: 1:1 led formation (Z)-alkene maj...

The stereoselective hydrolysis of esmolol in whole blood and in its separated components from rat, rabbit and human was investigated. Blood esterase activities were variable in different species in the order of rat>rabbit>human. Rat plasma showed the high esterase activity and had no stereoselectivity to enantiomers. Rabbit red blood cell (RBC) membrane, RBC cytosol and plasma all hydrolyzed es...

Although “Prelog’s rule” and “two hydrophobic binding pockets” model have been used to predict and explain the stereoselectivity of enzymatic ketone reduction, the molecular basis of stereorecognition by carbonyl reductases has not been well understood. The stereo selectivity is not only determined by the structures of enzymes and substrates, but also affected by the reaction conditions such as...

The mechanism and stereoselectivity in an organocatalyzed triple cascade reaction between an aldehyde, electron deficient olefin and an alpha,beta-unsaturated aldehyde are investigated for the first time using density functional theory. The factors responsible for high levels of observed stereoselectivity (Enders et al., Nature, 2006, 441, 861) towards the generation of cyclohexene carbaldehyde...

Several local anesthetics (LA) have been previously shown to block muscle batrachotoxin (BTX)-activated Na+ channels in planar bilayers. The mean dwell time of different LA drugs, however, varies widely, from less than 10 ms to longer than several seconds. In this study, we have examined the structural determinants that govern the dwell time, the binding affinity, and the stereoselectivity of L...

Propranolol is a nonselective beta-adrenergic blocker used as a racemic mixture in the treatment of hypertension, cardiac arrhythmias, and angina pectoris. For study of the stereoselective glucuronidation of this drug, the two propranolol glucuronide diastereomers were biosynthesized, purified, and characterized. A screen of 15 recombinant human UDP-glucuronosyltransferases (UGTs) indicated tha...

Aryl sulfotransferase (AST) IV (also named tyrosine-ester sulfotransferase and ST1A1) is a major phenol sulfotransferase in the rat, and it catalyzes the sulfation of many drugs, carcinogens, and other xenobiotics that contain phenol, benzylic alcohol, N-hydroxy arylamine, and oxime functional groups. Previous work discovered a stereospecificity of AST IV toward the enantiomers of 1,2,3,4-tetra...

Background: Ursodeoxycholic acid (UDCA) is an important clinical drug in the treatment of liver disease. In previous work, ursodeoxycholic acid was prepared by traditional organic synthesis. The preparation of ursodeoxycholic acid through an electrochemical method with higher stereoselectivity and environmental friendliness is described herein. Results: Dimethyl sulfoxide (DMSO), dimethylformam...

Propene monooxygenase has been cloned from Mycobacterium sp. strain M156, based on hybridization with the amoABCD genes of Rhodococcus corallinus B276. Sequencing indicated that the mycobacterial enzyme is a member of the binuclear nonheme iron monooxygenase family and, in gene order and sequence, is most similar to that from R. corallinus B-276. Attempts were made to express the pmoABCD operon...

The stereoselectivity of mouse skin metabolic activation to dihydrodiols of the strong carcinogen 5-methylchrysene (5-MeC) and the weak carcinogen 6-methylchrysene (6-MeC) was investigated. Synthetic 1,2-dihydro-1,2-dihydroxy-5-methylchrysene (5-MeC-1,2-diol), 5-MeC-7,8-diol, and 6-MeC-1,2-diol were resolved into their R,R- and S,S-enantiomers by chiral stationary phase high performance liquid ...