Interactions of Casein and Polypeptides in Multilayer Films Studied by FTIR and Molecular Dynamics

Multilayer films containing α- and β-casein and polypeptides, poly-L-lysine (PLL), and poly-L-arginine (PLArg) were formed by the layer-by-layer technique and Fourier Transform InfraRed spectroscopy with Attenuated Total Reflection (FTIR-ATR) and FTIR/Grazing Angle analyzed their i...

Full description

Bibliographic Details
Main Authors: Lilianna Szyk-Warszyńska, Katarzyna Raszka, Piotr Warszyński
Format: Article
Language:English
Published: MDPI AG 2019-05-01
Series:Polymers
Subjects:
Online Access:https://www.mdpi.com/2073-4360/11/5/920
Description
Summary:Multilayer films containing &#945;- and &#946;-casein and polypeptides, poly-L-lysine (PLL), and poly-L-arginine (PLArg) were formed by the layer-by-layer technique and Fourier Transform InfraRed spectroscopy with Attenuated Total Reflection (FTIR-ATR) and FTIR/Grazing Angle analyzed their infrared spectra. We investigated the changes of conformations of casein and polypeptides in the complexes formed during the build-up of the films. To elucidate the differences in the mechanism of complex formation leading to various growths of (PLL/casein)<sub>n</sub> and (PLArg/casein)<sub>n</sub> films, we performed the molecular dynamics simulations of the systems consisting of short PLL and PLArg chains and the representative peptide chains&#8212;casein fragments, which consists of several aminoacid sequences. The results of the simulation indicated the preferential formation of hydrogen bonds of poly-L-arginine with phosphoserine and glutamic acid residues of caseins. FTIR spectra confirmed those, which revealed greater conformational changes during the formation of casein complex with poly-L-arginine than with poly-L-lysine resulting from stronger interactions, which was also reflected in the bigger growth of (PLArg/casein)<sub>n</sub> films with the number of deposited layers.
ISSN:2073-4360