1H-nmr studies of the 20–31 fragment of calmodulin and of its cyclic analogue

✍ Scribed by Andrea Motta; Teodorico Tancredi; Gianfranco Borin; Ferdinando Marchiori; Evaristo Peggion; Pierandrea Temussi

• Book ID: 102762359
• Publisher: Wiley (John Wiley & Sons)
• Year: 1988
• Tongue: English
• Weight: 824 KB
• Volume: 27
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360270507

✦ Synopsis

High-resolution 'H-nmr spectroscopy at 500 MHz has been used to study the Ca2' binding domain I of bovine brain calmodulin in aqueous solution. All the resonances of the linear dodecapeptide Asp-Lys-Asp-Gly-Am-Gly-Thr-Ile-Thr-Thr-Lys-Glu and of its cyclic analogue, synthesized by classical solution methods, have been completely assigned using a combination of several one-and two-dimensional nmr experiments, including the zero quantum correlation. Chemical shift values and 3JCHNH coupling constants indicate that, on the nmr time scale, both peptides are flexible and assume multiple conformations in rapid equilibrium, with no relevant contribution of structured features. Addition of Ca" causes only minor spectral changes in aqueous solution of both peptides, while larger effects are observed in more hydrophobic mixtures such as water/trifluoroethanol. The linear analogue shows nonspecific interactions, while only As# and Am5 are significantly perturbed in the cyclic peptide. This evidence, together with identical findings in La3' titration studies of the cyclic analogue in pure water, suggest that loop I of calmodulin is endowed with an intrinsic binding ability.