2glg
From Proteopedia
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NMR structure of the [L23,A24]-sCT mutant
Overview
Salmon calcitonin (sCT) forms an amphipathic helix in the region 9-19, with the C-terminal decapeptide interacting with the helix (Amodeo, P., Motta, A., Strazzullo, G., Castiglione Morelli, M. A. (1999) J. Biomol., NMR 13, 161-174). To uncover the structural requirements for the hormone, bioactivity, we investigated several sCT analogs. They were designed so as, to alter the length of the central helix by removal and/or replacement of, flanking residues and by selectively mutating or deleting residues inside, the helix. The helix content was assessed by circular dichroism and NMR, spectroscopies; the receptor binding affinity in human breast cancer cell, line T 47D and the in vivo hypocalcemic activity were also evaluated. In, particular, by NMR spectroscopy and molecular dynamics calculations we, studied Leu(23),Ala(24)-sCT in which Pro(23) and Arg(24) were replaced by, helix inducing residues. Compared with sCT, it assumes a longer, amphipathic alpha-helix, with decreased binding affinity and one-fifth of, the hypocalcemic activity, therefore supporting the idea of a relationship, between a definite helix length and bioactivity. From the analysis of, other sCT mutants, we inferred that the correct helix length is located in, the 9-19 region and requires long range interactions and the presence of, specific regions of residues within the sequence for high binding affinity, and hypocalcemic activity. Taken together, the structural and biological, data identify well defined structural parameters of the helix for sCT, bioactivity.
About this Structure
2GLG is a Single protein structure of sequence from [1] with NH2 as ligand. Full crystallographic information is available from OCA.
Reference
Structural determinants of salmon calcitonin bioactivity: the role of the Leu-based amphipathic alpha-helix., Andreotti G, Mendez BL, Amodeo P, Morelli MA, Nakamuta H, Motta A, J Biol Chem. 2006 Aug 25;281(34):24193-203. Epub 2006 Jun 9. PMID:16766525
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