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Refined structure and metal binding site of the kalata B1 peptide. Arch Biochem Biophys 2002 Mar 15;399(2):142-8

Date

03/13/2002

Pubmed ID

11888199

DOI

10.1006/abbi.2002.2769

Scopus ID

2-s2.0-0037088544   60 Citations

Abstract

The cyclic polypeptide kalata B1 from the African plant Oldenlandia affinis DC consists of 29 amino acid residues with three disulfide linkages. In this study we used two-dimensional NMR spectroscopy to investigate the three-dimensional structure of the peptide and to determine the disulfide connectivities. Nuclear Overhauser effects (NOEs) between neighboring beta-protons of the cysteines detected at 750 MHz provided evidence for the disulfide connectivity pattern 5-13, 17-29, and 22-27. These disulfide linkages were confirmed by three-dimensional structures calculated from input constraints derived solely from NOEs without explicit disulfide connectivities. Kalata B1 is insoluble in aqueous solution above pH 3.5, but in a 50-50 water-methanol mixture, it was possible to use natural abundance two-dimensional (15)N-(1)H heteronuclear single quantum coherence spectroscopy to study the hydrophobic peptide from pH 2 to 10. The addition of methanol resulted in no significant structural changes. Although the peptide contains three prolyl residues, no evidence of multiple conformers was detected at any pH. The addition of Mn(2+) to kalata B1 resulted in selective broadening of resonances from Asn 23, Thr 24, and Glu 15; these results suggest that these three residues are involved in a specific metal binding site.

Author List

Skjeldal L, Gran L, Sletten K, Volkman BF

Author

Brian F. Volkman PhD Professor in the Biochemistry department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Binding Sites
Cyclotides
Disulfides
Hydrogen-Ion Concentration
Magnetic Resonance Spectroscopy
Metals
Models, Molecular
Peptides, Cyclic
Protein Conformation
Titrimetry
jenkins-FCD Prod-444 eb4ebd1a08581aba961d3befd3b851a3c3ec6b46