Figure 5.
Fig. 5. The interaction of a transition-state analog
(L-1-O-octyl-2-heptylphosphonyl-sn-glycero-3-phosphoethanolamine)
with the^ active site of the Class I PLA[2] from the venom of N.
n. atra (A). Class II PLA[2]s, including App-D49, substitute a
lysine residue^ for the tyrosine at sequence position 69. The
K69Y mutant has essentially the same activity as the wild type
enzyme toward PC^ and PE substrates but shows a 3-fold drop in
activity toward PG substrate. One explanation for this finding
is that the -ammonium
group of Lys-69 forms additional hydrogen bonds with
phospholipid^ head groups, especially with PG whose hydroxyl
groups can function as hydrogen bond acceptors (B). Such an
interaction would not be achievable by the phenolic oxygen of
Tyr-69 or with PC and^ PE as substrate.
The above figure is reprinted
by permission from the ASBMB:
J Biol Chem
(1997,
272,
3573-3582)
copyright 1997.
-ammonium
group of Lys-69 forms additional hydrogen bonds with
phospholipid^ head groups, especially with PG whose hydroxyl
groups can function as hydrogen bond acceptors (B). Such an
interaction would not be achievable by the phenolic oxygen of
Tyr-69 or with PC and^ PE as substrate.