Correlations between biological activities and conformational properties for human, salmon, eel, porcine calcitonins and Elcatonin elucidated by CD spectroscopy.
Eur J Biochem
; 221(3): 1117-25, 1994 May 01.
Article
em En
| MEDLINE
| ID: mdl-8181470
ABSTRACT
Calcitonin (CT) inhibits osteoclastic bone resorption and induces calcium uptake from body fluids. A comparative study of the conformational behaviours of therapeutic calcitonins [salmon (s), eel (e), a synthetic eel calcitonin analogue (Elcatonin), porcine (p) and human (h) calcitonins] as a function of solvent polarity and temperature have been performed by circular dichroism spectroscopy. Elements of secondary structure were lacking in H2O but could be observed in 2,2,2-trifluoroethanol and sodium dodecyl sulphate. In particular, similar amounts of alpha-helical content (four alpha-helical turns) were estimated in trifluoroethanol despite the considerable differences in amino acid sequences. The relative ability to form an alpha helix, assessed by trifluoroethanol/H2O titration, was found to be Elcatonin > sCT > pCT > eCT > hCT. In Elcatonin, sCT, pCT and eCT the four alpha-helical turns were promoted almost completely in a single step, between 0 and 35% trifluoroethanol, unlike hCT where helical structure formation has been reported to involve two steps over the whole trifluoroethanol/H2O range [Arvinte, T. & Drake, A. F. (1993) J. Biol. Chem. 268, 6408-6414]. In SDS, which mimics the membrane environment, conformational differences (3-4 helical turns in Elcatonin, sCT, eCT versus one helical turn in pCT, hCT) were observed and correlate well with biological activity (Elcatonin = sCT = eCT > pCT = hCT). Low-temperature studies in a cryogenic solvent mixture showed the formation of high alpha-helix content (similar to that in trifluoroethanol) in Elcatonin, sCT, eCT and pCT, whilst a left-handed extended helix (3(1) helix) was formed in hCT. This is consistent with the hypothesis of 'linear' and 'helical' calcitonin receptors [Nakanuta, H., Orlowski, R. C. & Epand, R. M. (1990) Endocrinology 127, 163-169].
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Conformação Proteica
/
Calcitonina
Limite:
Animals
/
Female
/
Humans
Idioma:
En
Revista:
Eur J Biochem
Ano de publicação:
1994
Tipo de documento:
Article
País de afiliação:
Reino Unido