METAP2 the exact mechanism of catalysis is not known and is studied via x-ray crystallography.
The bridging water or hydroxide ligand acts as a nucleophile during the hydrolysis reaction, but the exact mechanism of catalysis is not yet known. The catalytic mechanisms of hydrolase enzymes depend greatly on the identity of the bridging ligand, which can be challenging to determine due to the difficulty of studying hydrogen atoms via x-ray crystallography. 
