Strategies for discovery and improvement of enzyme function: state of the art and opportunities.
Bottom Line: Developments in the field of enzyme or reaction engineering have allowed access to means to achieve the ends, such as directed evolution, de novo protein design, use of non-conventional media, using new substrates for old enzymes, active-site imprinting, altering temperature, etc.Utilization of enzyme discovery and improvement tools therefore provides a feasible means to overcome this problem.The present review attempts to highlight some of these achievements and potential opportunities.
Affiliation: Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Hauz Khas, New Delhi - 110 016, India.Show MeSH
Mentions: Not even best of the screening strategies can guarantee obtaining a viable hit. In such cases, one may access known databases of culture collection centres and screen from the library of microorganisms. One of the prime example of this strategy resulted in identification of Alcaligenes faecalis ATCC 8750 as a very potent expresser of a highly enantioselective nitrilase acting on racemic mandelonitrile and produced (R)‐(‐)‐mandelic acid, a versatile chiral building block (Yamamoto et al., 1991a). The cyanohydrin undergoes in situ racemization, making it a dynamic kinetic resolution. An advantage of the nitrilase process is that no organic solvents are required and it avoids the synthesis of a nitrile, as the cyanohydrin is formed from benzaldehyde and hydrogen cyanide under the reaction conditions. The recombinant nitrilase expressed in Escherichia coli is presently being used by BASF (Ludwigshafen, Germany) (Ress‐Loschke et al., 2000), Nitto Chemical Industry (Tokyo, Japan) (Endo and Tamura, 1991; 1994; Endo et al., 1994) and Asahi Kasei Kogyo (Osaka, Japan) (Yamamoto et al., 1991b) on a multiton scale to produce optically pure mandelic acid along with its substituted derivatives. A. faecalis nitrilase has also been employed for other commercial processes. An immobilized form of the recombinant host (E. coli) expressing genetically modified nitrilase was also utilized for production of hydroxy methionine derivatives that find use as nutritional additive in cattle feed (Favre‐Bulle et al., 2001; Pierrard et al., 2001; Rey et al., 2004) (Fig. 3).
Affiliation: Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Hauz Khas, New Delhi - 110 016, India.