2np1
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CRYSTAL STRUCTURE OF NITROPHORIN 1 FROM RHODNIUS PROLIXUS
OverviewOverview
The nitrophorins are heme-based proteins from the salivary glands of the, blood-sucking insect Rhodnius prolixus that deliver nitric oxide gas (NO), to the victim while feeding, resulting in vasodilation and inhibition of, platelet aggregation. The nitrophorins also bind tightly to histamine, which is released by the host to induce wound healing. Here we present, three crystal structures of nitrophorin 1 (NP1): bound to cyanide, which, binds in a manner similar to NO (2.3 A resolution); bound to histamine, (2.0 A resolution); and bound to what appears to be NH3 from the, crystallization solution (2.0 A resolution). The NP1 structures reveal, heme to be sandwiched between strands of a lipocalin-like beta-barrel, and, in an arrangement unlike any other gas-transport protein discovered to, date. The heme is six-coordinate with a histidine (His 59) on the proximal, side, and ligand in a spacious pocket on the distal side. The structures, confirm that NO and histamine compete for the same binding pocket and, become buried on binding. The dissociation constant for histamine binding, was found to be 19 nM, approximately 100-fold lower than that for NO.
About this StructureAbout this Structure
2NP1 is a Single protein structure of sequence from Rhodnius prolixus with NH4, HEM and 2HP as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of a nitric oxide transport protein from a blood-sucking insect., Weichsel A, Andersen JF, Champagne DE, Walker FA, Montfort WR, Nat Struct Biol. 1998 Apr;5(4):304-9. PMID:9546222
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