Biocatalyst research

By rect comparison of structural and functional characteristics of different, naturally-occurring enzymes and modified biocatalysts, researchers hope to delineate the structural features controlling the hydrolytic and S3mthetic catalytic activities of this family of glucosylases. This understanchng will eventually lead to the ability to "engineer" glucan biocatalyst capability. 

Antibodies that bind to metallopoiphyrins provide an ideal cofactor in oxidation reactions, similar to cytochrome P-450 catalyzed oxidations. The metalloporphyrins provides the chemical activation site where the antibody exerts its selectivity (25), This antibody-mediated metalloporphyrin chemistry adds another dimension to the use of antibody catalysts in organic syntheses. Research on these systems has demonstrated that antibody technology represents a powerful and versatile tool for creating tailored biocatalysts. Research and development in this area should continue to generate efficient and robust catalysts with high specificity particularly for organic syntheses. 

L-Phenylalanine can be synthesised from trims-cinnamic add (Figure A8.12) catalysed by a L-phenylalanine ammonia-lyase from Rhodococcus glutinis. The commercialisation of the process was limited by the low conversion (70%), low stability of the biocatalyst and die severe inhibition exerted by trims-cinnamic add. These problems were largely overcome by researchers at Genex. The process, commercialised for a short period by Gen ex, involves a cell-free preparation of phenylalanine-ammonia-lyase activity from Rhodotorula rubra. 

As shown in this chapter, by focusing on the modulation of enzyme selectivity by medium engineering, quite simple modifications of the solvent composition can really have significant effects on the performances of the biocatalysts. The main drawback remains the lack of reliable predictive models. Despite the significant research efforts (particularly in the last decade), it is likely that a reasonable foresight of the enantioselective outcome of an enzymatic transformation will continue to be based solely on a careful analysis of the increasingly numerous literature reports. 

End N, Schoning K-U (2004) Immobilized Biocatalysts in Industrial Research and Production. 242 273-317... 

Indeed, recent research on the use of a cyanobacterium as a biocatalyst has opened up this area asymmetric reduction of ketones by a cyanobacteria, Syne-chococcus elongates PCC 7942, with the aid of light energy proceeded smoothly... 

One of the most interesting research fields in biocatalysis is the study of biocatalyst denaturation and stabilization in the reaction environment. In nonconventional media,... 

To improve biocatalyst recovery and ease of recycle, a research group reported immobilization of Gordona strain CYKS1 on celite beads [197], A cell loading of 1.5 mg cell/g celite was obtained. Use of immobilized biocatalyst at 50% v/v relative to aqueous buffer volume probably results in higher cell density however, the specific rate of desulfurization appeared to decrease. The reports did not have sufficient data to correctly... 

Further research in improving the BDS activity of the biocatalysts was targeted towards the search of co-catalysts and co-factors to enhance overall desulfurization rates as well as promoters to enhance enzyme expression. This research resulted in identification of NADH and FMNH2 as co-factors essential for electron transfer and related oxidoreductase enzymes as co-catalysts as described in detail below. Additionally, other bacterial strains were also investigated as hosts and are reported below. 

Biocatalysts Ltd. works through customer agreements with customer, so far, they already hold exclusivity agreements with some blue chip companies around the world. The R D program is focused on the development of new enzymes and enzyme complexes mainly identified by customers. British Universities undertake most of the needed basic research into new enzymes through allegiances with Biocatalyst Ltd. This allows the in-house scientists to focus onto the customers needs, whilst keeping full up to date with the latest developments in bioresearch. 

The research was oriented towards the development of biocatalysts for removal of recalcitrant sulfur heterocyclic compounds including benzothiophenes, naphthothio-phenes, and alkylbenzothiophenes. To begin with, they focused on asymmetric sulfur compounds in this class and developed a method for desulfurization of these compounds present in petroleum products [108], The identity of the microorganisms was not disclosed in the abstract but they do claim use of the enzymes as well in the application. 

The researchers from Waseda University have been following the most recent GE strategy for developing improved biocatalysts with desulfurization activity. They hold two patents, the first concerns with the use of Mycobacterium frei WU-0103 strain in a method for decomposing heterocyclic sulfur compounds [169], This bacterium has the ability for desulfurizing DBTs, benzothiophenes, naphthothiophene, and their alkyl derivatives, at 50°C. Details about this strain and the method can be found in Section 2.2.3 in Chapter 3. 

Some of the recent work from Japan has identified strains capable of desulfurizing dipentyl DBTs and other larger alkyl DBTs. Research in the area of substrate transport and identification of any active transport proteins would be greatly helpful in developing effective biocatalysts for desulfurization of larger molecules. Second, strains capable of desulfurization of benzonaphthothiophenes have also been identified [11]. Desulfurization of whole crude oils will require desulfurization of not just benzonaphthothiophenes... 

Provided that the research needs are satisfied, the development of bioprocessing alternatives would be dependent on improved biocatalysts. The biocatalyst has to be active towards multiple molecules (broader substrate specificity), with multi-functional capability (BDS-BDN-BDM), and adaptability to function in an oil environment, with... 

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