Enzyme-aided enantioselective

One example of such a course is the Haverford Laboratory in Chemical Structure and Reactivity (146) that includes six projects, each of which involves sample preparation, sample analysis and some kind of determination of the properties of the substance prepared. The projects include organopalladium chemistry, porphyrin photochemistry, enantioselective synthesis, computer-aided modeling, enzyme kinetics and electron transfer reactions. 

In any event, the recent growth of the area of enantioselective transformations with chemical catalysts and enzymes has greatly enhanced the overall potential of organic synthesis. Now, asymmetric synthesis of single enantiomers is becoming a common practice in laboratories (56). This volume will focus primarily on enantioselective transformations aided by substoichiometric amounts of chiral compounds. This chemistry is still young and primitive but is full of promise. See (57)... 

Since the enzyme reaction is reversible, conditions for the synthesis of Neu5Ac and natural or synthetic derivatives in high yield as well as of Kdn with the aid of bacterial lyase were elaborated (see section 6.1). The recombinant and overexpressed sialate-pyruvate lyase from E. coli is now in wide use as a speeific chiral catalyst which mediates highly enantioselective aldol condensation reactions leading to a variety of sialic acids. 

Duxbury and coworkers recently developed a new chiral enzyme-responsive polymer based on enantioselective polymer modification [151]. With the aid of two alcohol dehydrogenases that show opposite enantioselectivities in the reduction of ketones (ADH-LB and ADH-T), the two enantiomers of p-vinylpheny-lethanol were obtained in excellent yield and ee. Copolymers of these monomers with styrene using free radical polymerization afforded random block copolymers... 

The streptavidin variant is generated as a part of a screen of modifications. In this work, no asymmetric induction was obtained without protein, and the wild-type streptavidin (Sav) gave a reduction product of up to 57 % e.e. (/ ). However, the S112A mutant of Sav gave an amine in up to 96 % e.e. (R), and in other cases (e.g. S112K mutant) the enantioselectivity could even be reversed. In addition, up to 4000 turnovers of the synthetic enzyme were able to be achieved [133-137]. Computational and molecular modelling has been applied to this process to aid optimization [138]. 

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