Deracemisation of sec-alcohols by bio-stereoinversion

The transfromation of a racemate of a sec-alcohol to a single stereoisomeric sec-alcohol in 100% yield and 100% optical purity by biocatalytic methods will be investigated. It is known that Nature is able to perform this transformation, however this process works is not yet understood. For two deracemisation methods (one-pot/one- step and one-potwo-step) the enzymes responsible for the process will be identified and characterized, cloned and overexpressed. Determination of the stereoselectivity of each enzyme involved as well as determination if its activity will allow computer simalution of the process. Detailed investigation of the substrate pattern of the enzymes will allow to estimate, which types of sec-alcohol can be transformed. Biocatalytic deracemisation processes bear several significant economical and environmental aspects: (i) The overall atom efficiency is close to 100% when just one micro-organism/enzyme system is applied, which largely omits chemical waste during production. (ii) Typical for one-pot-procedures is, that the amount of hazardous organic solvents is significantly reduced. Furthermore, spent biocatalysts are easily to dispose of. (iii) Since actually only water (buffer) and the grown biocatalyst are needed, the methods represent a `green` chemical processes.

We could show that two controversial reaction conditions can be applied in one pot concurrently beside each other: the two reaction conditions are different to each other just as fire and water (oxidation and reduction). Nevertheless by choosing the appropriate biocatalysts the combination of the reaction conditions led to the transformation of a pair of hand gloves (left and right handed hand gloves) to two right-handed hand gloves or two left-handed hand gloves. In chemistry such transformations are of high importance to be able to produce (optically) pure compounds. For driving each transformation cheap reagents like molecular oxygen and glucose or formic acid where applied. In a related system we noticed that the additional reagents could be skipped. Like an Egyptian pharaoh rules the people from the top of a (social) pyramid or like a puppet player controls his marionette, a single biocatalyst on a superior level controlled and commanded two subordinated biocatalyst. The latter two interconverted continuously the image and the mirror image of a chemical compound (see above: left and right handed hand glove). The commanding biocatalyst controlled the two other biocatalysts via four chemical mediators resembling the officers in an agyptian society or the threats of a marionette. The superior enzyme determined whether the image compound or the mirror image compound was produced in excess; without commander the amounts of them remained or became equal.