Figure 6.
FIGURE 6. Proposed mechanism for mtFabH transacylation. The
formation of the thiolate ion at Cys122, which is crucial to the
transacylation reaction, appears to be promoted in part by the
helix dipole effect (represented here by a partial positive
charge at the N-terminal end of helix 5) and by shuttling of the
proton via water 568 and ultimately abstraction via N 2 of
His258. Through hydrogen bonding, the backbone nitrogens of
Gly322 and Cys122 stabilize the negative charge gained by the
acyl-CoA carbonyl during formation of the acyl-enzyme thioester
Michaelis complex (boxed). Data are adapted from Refs. 24 and 29.
The above figure is reprinted
by permission from the ASBMB:
J Biol Chem
(2005,
280,
32539-32547)
copyright 2005.
2 of
His258. Through hydrogen bonding, the backbone nitrogens of
Gly322 and Cys122 stabilize the negative charge gained by the
acyl-CoA carbonyl during formation of the acyl-enzyme thioester
Michaelis complex (boxed). Data are adapted from Refs. 24 and 29.