US EPA

1744935 

Technical Report 

Characterization of chemically modified enzymes for bioremediation- reactions. 1997 annual progress report 

Adams, MWW; Kaufman, EN 

1997 

NTIS/02924983_a 

GRA and I 

GRA and I 

Many, if not most, biological transformation reactions of interest to US Department of Energy (DOE) site remediation involve substrates that are only sparingly soluble in aqueous environments. Hence, destruction of these recalcitrant and toxic materials would benefit tremendously if their degradation could be performed in nonaqueous environments. Organic biocatalysis may be motivated by the nature of the substrate itself, augmented mass transport, ease of product recovery, or novel reaction pathways afforded by the organic solvent. For instance, polychlorinated biphenyls (PCBs) are sparingly soluble in water, but may be more effectively processed when solubilized by organic liquids. However, naturally-occurring enzymes are not soluble in organic solvents. Indeed, most spontaneously denature and, depending on the solvent used, typically form inactive and insoluble precipitates. The objective of the current work is to gain a fundamental understanding of the molecular and catalytic properties of enzymes that have been chemically-modified so that they are catalytically-active and chemically-thermally-stable in organic solvents. The premise for this study is that highly stable enzymes which are catalytically active in both water and in a range of organic solvents are optimally suited for bioremediation where substrates of interest are more soluble and may be processed with greater specificity in nonaqueous solvents. The proposed research program will enable the development of nonaqueous bioremediation technologies for the treatment of DOE sites contaminated with aqueous-insoluble organic compounds. Such compounds may include dense nonaqueous phase liquids, trichloroethylene (TCE), trichloroacetic acid, trans- dichloroethylene, diesel fuel, and PCBs. These compounds have been identified as targets for technology development in the 'EM Technology Needs Database' and are contaminants at the following DOE sites: K-25 Site plumes; ORNL WAGS 1, 4, and 5; Paducah plumes; Portsmouth plumes; the X-701B Holding Pond; and the Y-12 Poplar Creek and Bear Creek Watersheds. 

Enzymes; *Bioremediation; *Progress Report; *Molecular Structure; Decomposition; Structural Models; Genotype; Remedial Action; Decontamination; Decommissioning; EDB/550000; EDB/540000