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It was observed that a biocatalyst prepared from dehydrated whole cells of a recombinant Escherichia coli (initially suspended in borate buffer) was able to hydrolyze gaseous 1-chlorobutane in a solid/gas reactor. Nevertheless, at 40 degrees C and for a 0.7 water activity, it rapidly lost its activity. The explanation of this phenomenon was first investigated by observing the biocatalyst structure at the microscopic level and by studying the localization of the dehalogenase involved in catalysis (intracellular/extracellular). The behavior of this biocatalyst was then compared with that of a preparation made from cells extracts. The reasons of the inactivation are discussed in terms of thermal denaturation and protective effect of buffer salts., ((c) 2009 Wiley Periodicals, Inc.)

Although microwave-assisted reactions are widely applied in various domains of organic chemistry, their use in the area of enzyme chemistry has been rather limited, due to the high temperatures associated with the microwave heating: Because current technology, allows a good control of reaction parameters, several examples of microwave-assisted enzyme chemistry have been reported, using stable and effective biocatalysts (modified enzymes). The purpose of this review is to highlight the applications and studies on the influence of microwave irradiation on enzymatic properties and their application in enzyme chemistry.

One of the limiting steps in the further development of enzyme technology is the regeneration of cofactors, especially the pyridinic nucleotide cofactors. Immobilization of alcohol dehydrogenase and steroid dehydrogenase is described. In the last case stabilized enzymes could work in non aqueous solvents. Co-enzyme molecules are bound in the immediate vicinity of the active site of the enzyme. Cofactor regeneration was performed with an electron carrier (Phenazine methosulfate). Ageing phenomena were observed. The co-immobilization of superoxide dismutase gives rise to an increase of stability.