1euo
|
Crystal structure of nitrophorin 2 (prolixin-S)
OverviewOverview
Nitrophorin 2 (NP2) (also known as prolixin-S) is a salivary protein that, transports nitric oxide, binds histamine, and acts as an anticoagulant, during blood feeding by the insect Rhodnius prolixus. The 2.0-A crystal, structure of NP2 reveals an eight-stranded antiparallel beta-barrel, containing a ferric heme coordinated through His(57), similar to the, structures of NP1 and NP4. All four Rhodnius nitrophorins transport NO and, sequester histamine through heme binding, but only NP2 acts as an, anticoagulant. Here, we demonstrate that recombinant NP2, but not, recombinant NP1 or NP4, is a potent anticoagulant; recombinant NP3 also, displays minor activity. Comparison of the nitrophorin structures suggests, that a surface region near the C terminus and the loops between beta, strands B-C and E-F is responsible for the anticoagulant activity. NP2, also displays larger NO association rates and smaller dissociation rates, than NP1 and NP4, which may result from a more open and more hydrophobic, distal pocket, allowing more rapid solvent reorganization on ligand, binding. The NP2 protein core differs from NP1 and NP4 in that buried, Glu(53), which allows for larger NO release rates when deprotonated, hydrogen bonds to invariant Tyr(81). Surprisingly, this tyrosine lies on, the protein surface in NP1 and NP4.
About this StructureAbout this Structure
1EUO is a Single protein structure of sequence from Rhodnius prolixus with HEM and NH3 as ligands. Full crystallographic information is available from OCA.
ReferenceReference
The crystal structure of nitrophorin 2. A trifunctional antihemostatic protein from the saliva of Rhodnius prolixus., Andersen JF, Montfort WR, J Biol Chem. 2000 Sep 29;275(39):30496-503. PMID:10884386
Page seeded by OCA on Tue Nov 20 14:19:56 2007