Microbial cell-free extracts enzymatic activity

Chakrabarty has extensively reviewed the biodegradation of pesticides (J ). Table I shows the results of several studies on the enzymatic activity of microbial cell-free extracts for pesticide degradation. Clearly, there is substantial evidence to suggest that enzymes might be used in the development of biotechnology for use in degradation of pesticides. 

Table I. Enzymatic Activity of Microbial Cell-Free Extracts For Pesticide Degradation...

The conversion of D-glucose (17) into D-fructose (9) by a microbial enzyme (Scheme 5) was first reported in 1957 when Marshall and Kooi found glucose isomerase activity in cell-free extracts of Pseudomonas hydrophila (91. This enzymatic activity was enhanced in the presence of arsenate. Soon thereafter, other arsenate-requiring enzymes were isolated from Aerobacter sp. as well as Escherichia freundii [10]. Enzymes required arsenate when D-glucose or D-fructose was the substrate but not when the corresponding 6-phosphates 11 and 12 were offered. Purification of the arsenate-dependent principle component from Escherichia intermedia allowed the conclusion that the enzyme was a glucose 6-phosphate isomerase (EC 5.3.1.9) that was able to isomerise free D-glucose when it was complexed with arsenate [11]. 

The enzymatic activity in soil is mainly of microbial origin, being derived from intracellular, cell-associated or free enzymes. Only enzymatic activity of ecto-enzymes and free enzymes is used for determination of the diversity of enzyme patterns in soil extracts. Enzymes are the direct mediators for biological catabolism of soil organic and mineral components. Thus, these catalysts provide a meaningful assessment of reaction rates for important soil processes. Enzyme activities can be measured as in situ substrate transformation rates or as potential rates if the focus is more qualitative. Enzyme activities are usually determined by a dye reaction followed by a spectrophotometric measurement. 

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