Open AccessThe Solution Structure of the Synthetic Circular Peptide
Author(s) -
Rietman B. H.,
Folkers P. J. M.,
Folmer R. H. A.,
Tesser G. I.,
Hilbers C. W.
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0706w.x
Subject(s) - peptide , protein secondary structure , chemistry , peptide sequence , amino acid , protein structure , protein folding , folding (dsp implementation) , dna , cyclic peptide , stereochemistry , biophysics , biochemistry , gene , biology , electrical engineering , engineering
The cyclic disulfide peptide was prepared to obtain a constrained analogue of residues 17–27 of the DNA‐binding loop of the gene‐V‐encoded ssDNA‐binding protein of filamentous bacteriophage M13. Amino acid sequences very similar to that of this β‐loop have been found in various phage‐encoded ssDNA‐binding proteins, and it has been proposed that such a loop may occur as a common motif in this class of proteins. The conformation, in aqueous solution, of the synthetic gene‐V‐protein binding‐loop analogue has been investigated by means of two‐dimensional‐ 1 H‐NMR techniques. Subsequent structure calculations show that the molecule forms a β‐loop that includes a turn formed by three residues. This structure, very unusually for a cyclic disulfide peptide, is highly similar to that of the analogous part of the binding loop of the native protein. Comparison with experiments on other cyclic disulfide peptides indicates that the formation, of the β‐sheet (β‐hairpin) secondary structure is essentially governed by the amino acid composition of the 11‐residue sequence. The disulfide bridge in the 11‐residue sequence is essential for conformational stability, as indicated by the finding that the open peptide analogue that encompasses residues Ser17–Ser27 does not adopt a detectable secondary structure in water. The bridge replaces the role of the loop formed by residues 49–58 in the protein, which act as a scaffold to hold the N‐terminal and C‐terminal ends of the DNA‐binding loop together.