Figure 4 Proposed mechanism for -CA.
(A) Bicarbonate bound in the active site, in a position similar
to that seen for the acetic acid molecule, forming hydrogen
bonds with Gly224, Asp162 and Glu151. (B) This molecule
decomposes into CO, which continues to interact with Gln151'
and hydroxide. (C) CO diffuses out of the active site leaving
a hydroxide ion bound to the zinc. This ion then accepts a
proton from a buffer molecule in bulk solvent, leaving water
bound at the active site zinc (D).
The above figure is reprinted
from an Open Access publication published by Macmillan Publishers Ltd: