2q9i | pdb_00002q9i
Crystal Structure of D-Dimer from Human Fibrin Complexed with Met-His-Arg-Pro-Tyr-amide.
Structural highlights
DiseaseFIBG_HUMAN Defects in FGG are a cause of congenital afibrinogenemia (CAFBN) [MIM:202400. This rare autosomal recessive disorder is characterized by bleeding that varies from mild to severe and by complete absence or extremely low levels of plasma and platelet fibrinogen. Note=Patients with congenital fibrinogen abnormalities can manifest different clinical pictures. Some cases are clinically silent, some show a tendency toward bleeding and some show a predisposition for thrombosis with or without bleeding. FunctionFIBG_HUMAN Fibrinogen has a double function: yielding monomers that polymerize into fibrin and acting as a cofactor in platelet aggregation. 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 PubMedIn a recent report, we showed that alanine can replace glycine at the amino terminus of synthetic B-knobs that bind to human fibrin(ogen). We now report a survey of 13 synthetic peptides with the general sequence XHRPYam, all tested with regard to their ability to delay fibrinolysis in an in vitro system activated by t-PA, the results being used as measures of binding affinity to the betaC hole. Unexpectedly, some large and bulky amino acids, including methionine and arginine, are effective binders. Amino acids that branch at the beta carbon (valine, isoleucine, and threonine) do not bind effectively. Crystal structures were determined for two of the peptides (GHRPYam and MHRPYam) complexed with fibrin fragment D-dimer; the modeling of various other side chains showed clashing in the cases of beta-carbon substituents. The two crystal structures also showed that the enhanced binding observed with pentapeptides with carboxyl-terminal tyrosine, compared with that of their tetrapeptide equivalents, is attributable to an interaction between the tyrosine side chain and a guanidino group of a nearby arginine (beta406). The equivalent position in gamma-chains of human fibrin(ogen) is occupied by a lysine (gamma338), but in chicken and lamprey fibrin(ogen), it is an arginine, just as occurs in beta chains. Accordingly, the peptides GPRPam and GPRPYam, which are surrogate A-knobs, were tested for their influence on fibrin polymerization with fibrinogen from lamprey and humans. In lampreys, GPRPYam is a significantly better inhibitor, but in humans, it is less effective than GPRPam, indicating that in the lamprey system the same tyrosine-arginine interaction can also occur in the gamma-chain setting. Probing the beta-chain hole of fibrinogen with synthetic peptides that differ at their amino termini.,Doolittle RF, Pandi L Biochemistry. 2007 Sep 4;46(35):10033-8. Epub 2007 Aug 10. PMID:17688324[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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