NSF Award
8800572
High-value fine chemicals are frequently prepared in a more efficient and economical manner by the use of regioselective and/or stereoselective oxidoreductase enzymes in place of conventional catalysts. However, such oxidoreductase enzymes consume expensive nicotinamide coenzymes--nicotinamide adenine dinucleotide (NAD) or its phosphorylated analog (NADP). Consequently, the practical use of nicotinamide coenzymes is limited to situations in which they can be regenerated in situ. Nicotinamide coenzymes exist in two forms: the reduced form (NAD(P)H) and the oxidized form (NAD(P) ). A major obstacle to the commercial use of oxidoreductase enzymes is the absence of a large-scale, economical nicotinamide coenzyme-regeneration process. During Phase I of the program, a novel process for the efficient and continuous regeneration of nicotinamide coenzymes was developed. The process, based on the chemical coupling of an NAD-linked reaction with a highly specific membrane separation, allows an inexpensive sacrificial reducing agent or sacrificial oxidizing agent to quantitatively regenerate NAD(P)H and NAD(P) , respectively. The goal of the Phase II program is to further characterize the membrane-assisted coenzyme recycling process with the aim of assembling a database of information appropriate for process optimization and design of a scaled-up system. Specifically, the technical objectives are 1) to identify and measure the factors that govern the efficiency of the coenzyme recycling process, 2) to assemble a membrane-reactor system for the production of an amino acid utilizing the recycling process, 3) to evaluate the performance of this membrane-reactor system, and 4) to evaluate the economics of the amino acid production process. In this Phase II program, further exploration of the membrane- assisted process that offers a simple, economical method to recycle the expensive coenzymes needed for the production of extremely pure specialty chemicals will be carried out. If these specialty chemicals can be produced economically, they will have a wide variety of potential uses, including the production of flavors, fragrances, food additives, pharmaceuticals, herbicides, and pesticides. As an example, it is estimated that the coenzyme-recycling process can produce L-phenylalanine, a component of the artificial sweetner aspartame at a cost savings of 45 percent compared with current L-phenylalanine production costs. Based on Phase I feasibility studies, it is expected that similar cost savings will be incurred in the production of other specialty chemicals. Also, it is expected that variations of this coenzyme-recycling process can be used to provide an efficient method to regenerate expensive or unstable reagents needed in clinical and environmental analytical procedures and sensor technology.
