Differences in Binding Specificity for the Homologous gamma- and beta-Chain "Holes" on Fibrinogen: Exclusive Binding of Ala-His-Arg-Pro-amide by the beta-Chain Hole.Doolittle, R.F., Chen, A., Pandi, L.
(2006) Biochemistry 45: 13962-13969
- PubMed: 17115691
- DOI: https://doi.org/10.1021/bi061219e
- Primary Citation of Related Structures:
- PubMed Abstract:
The beta-chain amino-terminal sequences of all known mammalian fibrins begin with the sequence Gly-His-Arg-Pro- (GHRP-), but the homologous sequence in chicken fibrin begins with the sequence Ala-His-Arg-Pro- (AHRP-). Nonetheless, chicken fibrinogen binds the synthetic peptide GHRPam, and a previously reported crystal structure has revealed that the binding is in exact conformance with that observed for the human GHRPam-fragment D complex. We now report that human fibrinogen, which is known not to bind APRP, binds the synthetic peptide AHRPam. Moreover, a crystal structure of AHRPam complexed with fragment D from human fibrinogen shows that AHRPam binds exclusively to the beta-chain hole and, unlike GHRPam, not at all to the homologous gamma-chain hole. The difference can be attributed to the methyl group of the alanine residue clashing with a critical carboxyl group in the gammaC hole but being accommodated in the roomier betaC hole where the equivalent carboxyl is situated more flexibly.
Department of Chemistry and Biochemistry and Division of Biology, University of California at San Diego, La Jolla, California 92093-0314, USA. firstname.lastname@example.org