Polypeptide Adsorption on a Synthetic Montmorillonite: A Combined Solid‐State NMR Spectroscopy, X‐ray Diffraction, Thermal Analysis and N 2 Adsorption Study

Two homopolypeptides, polylysine and polyglutamic acid, were adsorbed on a synthetic montmorillonite clay, in acidic medium. These organic‐inorganic complexes can be heated up to 110 °C without any degradation of the polypeptide. 1 H‐ 13 C CP‐MAS NMR spectra show that these polypeptides, which exhibit a mixture of α‐helical and random coil conformations in the bulk, tend to unfold and adopt a more extended random coil structure on adsorption on the phyllosilicate. The values of the basal spacing measured by X‐ray diffraction on dehydrated samples clearly indicate that in the presence of adsorbed polypeptide, the silicate layers do not collapse. The incorporation of polypeptide fragments within the interlayer space is also revealed by the decrease in the specific surface areas measured by N 2 ‐adsorption BET experiments. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)