Structural Biochemistry/Enzyme/Metalloproteases

Overview
Metalloproteases contain an active site that has a bound metal ion; this metal is almost always zinc. Metalloproteases are enzymes which catalyze reactions. Although the metal found is almost always zinc, the reactions can proceed with cobalt as well. The metal ion activates a water molecule to carry out a nucleophilic attack on a carbonyl peptide bond. A base is present to help deprotonate the metal-bound water.

There are two major types of metalloproteases: metalloendopeptidases and metalloexopeptidases. Some common metalloproteases that have been studied are carboxypeptidase A and B, as well as thermolysin, which are digestive enzymes. Thermolysin can be observed in its production from the bacteria by the bacteria Bacillus thermoproteolyticus.



Mechanism of Metalloproteases
Metalloproteases contain on their active site usually a bound metal ion (most of the time Zinc). The metal ion activates a water molecule to act as a nucleophile and attack the peptide carbonyl group. Bound to the active site is a base that pulls a proton from the water molecule bound to the metal in order to turn the water molecule into a nucleophile to attack the peptide bond.