Figure 6.
Fig. 6. Scheme of principal steps in the sequence of
reactions catalyzed by Fpg, showing catalytically important
amino acid residues. Nucleophilic attack at C1' and protonation
at O4' (a) lead to base displacement and deoxyribose ring
opening. A Schiff base involving Pro-1 is formed with O4'
stabilized by hydrogen bonding to Glu-2. b, following
abstraction of the 2' proton of deoxyribose by a general base,
Lys-56 protonates the 3'-phosphate leading to -elimination
(c). Deprotonation of C4', now vinilogous to C1', is followed by
protonation of the 5'-phosphate by Arg-258 and the second -elimination
event (c).
The above figure is reprinted
by permission from the ASBMB:
J Biol Chem
(2002,
277,
19811-19816)
copyright 2002.
-elimination
(c). Deprotonation of C4', now vinilogous to C1', is followed by
protonation of the 5'-phosphate by Arg-258 and the second