1poa
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| , resolution 1.5Å | |||||||
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| Ligands: | |||||||
| Activity: | Phospholipase A(2), with EC number 3.1.1.4 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
INTERFACIAL CATALYSIS: THE MECHANISM OF PHOSPHOLIPASE A2
OverviewOverview
A chemical description of the action of phospholipase A2 (PLA2) can now be inferred with confidence from three high-resolution x-ray crystal structures. The first is the structure of the PLA2 from the venom of the Chinese cobra (Naja naja atra) in a complex with a phosphonate transition-state analogue. This enzyme is typical of a large, well-studied homologous family of PLA2S. The second is a similar complex with the evolutionarily distant bee-venom PLA2. The third structure is the uninhibited PLA2 from Chinese cobra venom. Despite the different molecular architectures of the cobra and bee-venom PLA2s, the transition-state analogue interacts in a nearly identical way with the catalytic machinery of both enzymes. The disposition of the fatty-acid side chains suggests a common access route of the substrate from its position in the lipid aggregate to its productive interaction with the active site. Comparison of the cobra-venom complex with the uninhibited enzyme indicates that optimal binding and catalysis at the lipid-water interface is due to facilitated substrate diffusion from the interfacial binding surface to the catalytic site rather than an allosteric change in the enzyme's structure. However, a second bound calcium ion changes its position upon the binding of the transition-state analogue, suggesting a mechanism for augmenting the critical electrophile.
About this StructureAbout this Structure
1POA is a Single protein structure of sequence from Naja atra. Full crystallographic information is available from OCA.
ReferenceReference
Interfacial catalysis: the mechanism of phospholipase A2., Scott DL, White SP, Otwinowski Z, Yuan W, Gelb MH, Sigler PB, Science. 1990 Dec 14;250(4987):1541-6. PMID:2274785
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