1d3s
From Proteopedia
1.4 A crystal structure of nitrophorin 4 from Rhodnius prolixis at pH=5.6.
Structural highlights
FunctionNP4_RHOPR Heme-based protein that deliver nitric oxide gas (NO) to the victim while feeding, resulting in vasodilation and inhibition of platelet aggregation. Also bind tightly to histamine, which is released by the host to induce wound healing (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe nitrophorins comprise an unusual family of proteins that use ferric (Fe(III)) heme to transport highly reactive nitric oxide (NO) from the salivary gland of a blood sucking bug to the victim, resulting in vasodilation and reduced blood coagulation. We have determined structures of nitrophorin 4 in complexes with H2O, cyanide and nitric oxide. These structures reveal a remarkable feature: the nitrophorins have a broadly open distal pocket in the absence of NO, but upon NO binding, three or more water molecules are expelled and two loops fold into the distal pocket, resulting in the packing of hydrophobic groups around the NO molecule and increased distortion of the heme. In this way, the protein apparently forms a 'hydrophobic trap' for the NO molecule. The structures are very accurate, ranging between 1.6 and 1.4 A resolutions. Nitric oxide binding to nitrophorin 4 induces complete distal pocket burial.,Weichsel A, Andersen JF, Roberts SA, Montfort WR Nat Struct Biol. 2000 Jul;7(7):551-4. PMID:10876239[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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