Catalytic mechanism and maturation of the metalloenzyme nitrile hydratase.

摘要

Nitrile hydratases are metalloenzymes that catalyze the hydration of nitriles to their corresponding amides in a specific manner at ambient pressures and temperatures at neutral pH. Traditional industrial methods require high temperature and pressure, extreme pH, and heavy metals. NHases are used as biocatalysts in the large scale industrial production of amide precursors to textiles, animal feedstock, and polymers. Notably, NHase is used in the production of ~100,000 tons of acrylamide annually by the Mitsubishi Corporation.;Despite being used extensively in industry, questions remain about NHase. The catalytic mechanism is not defined. Understanding the way in which the nitrile is converted to amide will be useful for engineering a more efficient, specific, and stable enzyme. The improved enzyme will shift industry towards green chemistry. Additionally, the enzyme has a unique metallocenter. Understanding the chemistry of the enzyme will give new information on this rare enzyme configuration.;The maturation mechanism is not understood for NHase. It is understood that activator proteins may act as metallochaperones, bringing the metal to the active site. Metallochaperones regulate potentially toxic, but essential metals in cells. By understanding NHase's maturation, we can not only apply the knowledge to NHase understanding and engineering, but also to similar metallochaperones that may be responsible for causing Alzheimer's disease and the like.;The goal of the dissertation is to answer these questions. The catalytic mechanism will be investigated by studying reaction intermediates using spectroscopic techniques. The activator protein and NHase maturation will be studied with biophysical methods to probe its metal binding and protein-protein interactions.