1slf

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spinqualitylabelsall models 1slf, resolution 1.76Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

APOSTREPTAVIDIN, PH 5.6, TWO MOLECULES OF (SO4)2 BOUND AT THE BIOTIN BINDING SITE

Overview

The streptavidin-bound crystal structures of two disulfide-bridge cyclic, peptides (cyclo-Ac-[CHPQGPPC]-NH2 and cyclo-Ac-[CHPQFC]-NH2) and of a, linear peptide (FSHPQNT) were determined, as well as the structure of, apostreptavidin (streptavidin-sulfate). Both the linear and, disulfide-bridged cyclic peptides studied share a common HPQ conformation, and make common interactions with streptavidin, although significant, differences in structures and interactions occur for flanking residues, among the complexes. The conformation of the linear peptide in the crystal, structure of streptavidin-FSHPQNT was found to differ from that in the, same complex published [Weber, P. C., Pantoliano, M. W., & Thompson, L. D., (1992) Biochemistry 31, 9350-9354]. In the present investigation, the, HPQNT portion of the ligand is well-defined with some density defining the, Phe, whereas in the investigation of Weber et al. only the HPQ segment of, the bound peptide could be interpreted. Both bound cyclic peptides adopt a, beta-turn involving an H-bond between the His main chain carbonyl and the, main chain amide NH of the i+3 residue. In the streptavidin-bound, cyclo-Ac-[CHPQFC]-NH2 structure, there is an additional H-bond, indicative, of alpha-helix, between the main chain His carbonyl and the main chain, C-terminal Cys amide NH group. Binding interactions for both cyclic and, linear peptides include direct H-bonds, H-bonds mediated by tightly bound, water molecules, and hydrophobic interactions. The above structures and, that of streptavidin-biotin in the literature are compared and discussed, in the context of structure-based ligand design.

About this Structure

1SLF is a Single protein structure of sequence from Streptomyces avidinii with SO4 as ligand. Full crystallographic information is available from OCA.

Reference

Binding to protein targets of peptidic leads discovered by phage display: crystal structures of streptavidin-bound linear and cyclic peptide ligands containing the HPQ sequence., Katz BA, Biochemistry. 1995 Nov 28;34(47):15421-9. PMID:7492542

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