Aromatic Dehalogenases: Insights into Structures, Mechanisms, and Evolutionary Origins

摘要: Chlorinated aromatic compounds are among the most significant environmental contaminants introduced into environment by human activities. Pesticides such as atrazine, 2,4-D (2,4-dichlorophenoxyacetic acid), and pentachlorophenol intentionally, while PCBs have been released accidentally or poor disposal practices in past. Many of these novel xenobiotic (foreign to life), therefore microorganisms may not enzymes capable transforming them. As expected, many chlorinated xenobiotics quite resistant biodegradation. However, degrading often isolated from contaminated sites, suggesting that can adapt presence evolving new metabolic pathways allow them either take advantage a nutrient source destroy toxin. The participate newly evolved be acquired horizontal transfer another organism, recruitment pre-existing cellular protein has at least modest ability catalyze needed reaction. Given sufficient time selective pressure, genetic changes occur will improve function recruited proteins. It is, course, clear what length is “sufficient”. anthropogenic aromatics present for less than century. That period, an eye-blink nearly 4 billion-year history life on earth, apparently enough get process started, but unlikely long generate their usual level sophistication terms regulation catalytic proficiency. Biodegradation requires removal chlorine substituents before after ring cleaved, although highly some PCBs, chlorines must removed cleavage. dehalogenases accomplish difficult task removing rings subject