COENZYME RECYCLING USING A MEMBRANE REACTOR

ENZYME-CATALYZED REACTIONS OFFER ATTRACTIVE PROCEDURES FOR PREPARING PURE ENANTIOMERS, INCLUDING PHARMACEUTICALS, INSECTICIDES, AND HERBICIDES. DESPITE A PLETHORA OF ATTRACTIVE FEATURES, ENZYMES HAVE NOT BEEN WIDELY ACCEPTED AS ROUTINE CATALYSTS FOR THE PREPARATION OF PURE ENANTIOMERS. ONE REASON FOR THIS IS THAT MANY ENZYMES REQUIRE COFACTORS CALLED COENZYMES TO BE CATALYTICALLY ACTIVE. COENZYMES ARE EXPENSIVE AND MAKE THE PROCESS UNECONOMICAL. A GROUP OF ENZYMES PARTICULARLY WELL SUITED FOR THE PREPARATION OF PURE ENANTIOMERS ARE THE OXIDOREDUCTASES THAT USE NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD) AS A COENZYME. PRACTICAL PROCESSES CAN BE DEVISED USING CATALYTIC QUANTITIES OF THE COENZYME WHEN THE ENZYME REACTION IS COUPLED TO A COENZYME REGENERATION SCHEME. THE BEST CURRENTLY AVAILABLE COENZYME REGENERATION SCHEMES HAVE A NUMBER OF DRAWBACKS, INCLUDING THE FOLLOWING: 1) THEY USE EXPENSIVE ENZYME CATALYSTS, AND 2) THE REGENERATION SCHEME PRODUCES BYPRODUCTS THAT COMPLICATE THE ISOLATION OF THE DESIRED PRODUCT. IN THIS PROPOSAL BEND RESEARCH, INC. DESCRIBES A NEW PROCESS FOR NADH REGENERATION USING THE INEXPENSIVE ENZYME ALCOHOL DEHYDROGENASE OBTAINED FROM YEAST. THE NOVEL PART OF OUR REGENERATION SCHEME IS THE USE OF A MEMBRANE REACTOR TO CONTINUOUSLY AND SELECTIVELY REMOVE THE PRODUCT OF THE REGENERATION REACTION, ACETALDEHYDE, AND THEREBY DRIVE THE REACTION TO COMPLETION. THE PROPOSE TO DEMONSTRATE THE PRACTICALITY OF THIS REGENERATION SCHEME BY COUPLING OUR REGENERATION PROCESS TO THE PRODUCTION OF CHIRAL D-LACTIC ACID, AN EXPENSIVE PRECURSOR USED IN THE SYNTHESIS OF SEVERAL COMMERCIAL HERBICIDES.