Contaminant-metabolizing enzymes

Collier, T.K. and U. Varanasi. 1991. Hepatic activities of xenobiotic metabolizing enzymes and biliary levels of xenobiotics in English sole (Parophrys vetulus) exposed to environmental contaminants. Arch. Environ. Contam. Toxicol. 20 462-473. 

Goldstein, J.A., Friesen, M., Linder, R.E., Hickman, P, Hass, J.R. Bergman, H. (1977) Effects of pcntachlorophenol on hepatic drug-metabolizing enzymes and porphyria related to contamination with chlorinated dibenzo-/i-dioxins and dibenzo-furans. Biochem. Phamiacol., 26, 1549-1557... 

Collier, T.K., S.V. Singh, Y.C. Awasthi and U. Varanasi. Hepatic xenobiotic metabolizing enzymes in two species of benthic fish showing different prevalences of contaminant-associated liver neoplasms. Toxicol. Appl. Pharmacol. 113 319-324, 1992. 

With regard to toxicity, interactions with co-contaminants concern not only the actual toxicant/target interaction, but may also influence the adsorption, distribution and excretion (i.e. kinetics), the biotransformation (i.e. metabolism) or the bioavailability (Tichy, Cikrt and Roth, 1994). The primary impacts may be due to alterations in transport and distribution, changes in membrane properties, effects on metabolizing enzymes or competition for conjugation reactions. The resulting activities of a chemical mixture may be... 

Collier TK, Stein JE, Wallace RJ, Varanasi U (1986) Xenobiotic metabolizing enzymes in spawning English sole (Parophrys vetulus) exposed to organic-solvent extracts of marine sediments from contaminated and reference areas. Comp Biochem Physiol 84C 291-298. 

In some cases, microorganisms can transform a contaminant, but they are not able to use this compound as a source of energy or carbon. This biotransformation is often called co-metabolism. In co-metabolism, the transformation of the compound is an incidental reaction catalyzed by enzymes, which are involved in the normal microbial metabolism.33 A well-known example of co-metabolism is the degradation of (TCE) by methanotrophic bacteria, a group of bacteria that use methane as their source of carbon and energy. When metabolizing methane, methanotrophs produce the enzyme methane monooxygenase, which catalyzes the oxidation of TCE and other chlorinated aliphatics under aerobic conditions.34 In addition to methane, toluene and phenol have been used as primary substrates to stimulate the aerobic co-metabolism of chlorinated solvents. 

Organic contaminants such as petroleum hydrocarbons or chlorinated solvents can be directly metabolized by proteins and enzymes, leading to the degradation, metabolism, or mineralization of the contaminants. Furthermore, many of these contaminants can be broken down into harmless products or converted into a source of food and energy for the plants or soil organisms.50... 

Two of the most widely used and detected UV filters in the environment and WWTPs are BP3 and 4-MBC. Thus, they were the selected compounds to study individually their degradation by fungi [44, 49]. Studies with BP1, not only a BP3 metabolite but also an industrial UV filter (but its use in cosmetics is not allowed) itself have also been performed. Studies in liquid media allow a better analysis and monitoring of many parameters, both the contaminant concentration and the fungal metabolic state such as glucose consumption and enzyme production. In these studies, the degradation process was performed with the fungus in form of pellets. 

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