Layer of Clay Platelets in a Peptide Matrix: Binding, Encapsulation, and Morphology

Monte Carlo simulations are performed to study the binding of peptides (M1: (1)H(2)G(3)I(4)N(5)T(6)T(7)K(8)P(9)F(10)K(11)S(12)V) to a stack of mobile clay platelets and evaluate the morphological responses on a cubic lattice. A coarse-grained description is used to model both platelets and peptides capturing the specificity of each residue. Mobility profiles of residues and their proximity to platelets (i.e., the local structural profile) suggest that the peptide binding is anchored by (7)Lys and (10)Lys. Correlation between the density profiles of platelets and peptides aided by the visual analysis shows that (i) the layered morphology is maintained due to peptide binding, (ii) the interstitial spacing between platelets, that is, the gallery width decreases on increasing the peptide concentration (consistent with recent experiments), (iii) relatively smaller amplitude of oscillations in peptide density profile around the inner clay galleries suggests that the peptides are more likely to bind at the layer boundaries and exterior surface of the platelets than intercalate. The radius of gyration (R-g) of the peptide shows nonmonotonic dependence on the peptide concentration (C-p). (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 2566-2574, 2010