Figure 6.
FIG. 6. Proposed stereochemistry along the catalytic
process based on x-ray structures of tAsS complexes. Putative
hydrogen bonds are shown by dotted lines. A, tAsS complex with
U-shaped ATP and citrulline. B, tAsS complex with U-shaped ATP,
citrulline, and aspartate. Aspartate is adjacent to the -phosphate of ATP and
the ureido group of citrulline. C and D, tAsS complex with
S-shaped ATP, citrulline, and aspartate. ATP changes its
triphosphate conformation. D, citrulline changes its side-chain
conformation to approach the -phosphate of ATP (D).
E, tAsS complex with citrullyl-AMP intermediate. F, tAsS complex
with AMP and the product argininosuccinate.
The above figure is reprinted
by permission from the ASBMB:
J Biol Chem
(2003,
278,
22964-22971)
copyright 2003.
-phosphate of ATP and
the ureido group of citrulline. C and D, tAsS complex with
S-shaped ATP, citrulline, and aspartate. ATP changes its
triphosphate conformation. D, citrulline changes its side-chain
conformation to approach the