Investigating the inclusion properties of aromatic amino acids complexing beta-cyclodextrins in model peptides

Abstract

Cyclodextrins are commonly used as complexing agents in biological, pharmaceutical, and industrial applications since they have an effect on protein thermal and proteolytic stability, refolding yields, solubility, and taste masking. β-cyclodextrins (β-CD), because of their cavity size are a perfectly suited complexing agent for many common guest moieties. In the case of peptide-cyclodextrin and protein-cyclodextrin host-guest complexes the aromatic amino acids are reported to be the principal responsible of the interaction. For these reasons, we have investigated the inclusion properties of nine designed tripeptides, obtained permuting the position of two L-alanines (Ala, A) with that of one L-tryptophan (Trp, W), L-phenylalanine (Phe, F), or L-tyrosine (Tyr, Y), respectively. Interestingly, the position of the aromatic side-chain in the sequence appears to modulate the β-CD:peptide binding constants, determined via UV-Vis and NMR spectroscopy, which in turn assumes values higher than those reported for the single amino acid. The tripeptides containing a tyrosine showed the highest binding constants, with the central position in the Ac-AYA-NH2 peptide becoming the most favorite for the interaction. A combined NMR and Molecular Docking approach permitted to build detailed complex models, highlighting the stabilizing interactions of the neighboring amino acids backbone atoms with the upper rim of the β-CD.

Synthesis and Characterization of Host Guest Inclusion Complexation of Cyclic Oligosaccharide with Industrially Potent Dye in Different Phases by Physicochemical Contrivance

“…The double reciprocal plots were made on the basis of Benesi–Hildebrand equation for IC of 1 : 1 stoitiometry. We divided the intercept by the slope obtained from the straight line of the double reciprocal plot and thereby calculated association constants (K a ) at three different temperatures …”

Sustenance of Inclusion Complexes of Ionic Liquid with Cyclic Oligosaccharide Molecules in Liquid and Solid Phases by Diverse Approaches

“…The changes in the values of absorbance (ΔA) of IL (at λ max =252 nm) were recorded at three different temperatures to determine the association constants ( K a ) (Tables2 and See supporting information Table S8−S10) . Basing on the Benesi−Hildebrand method for 1:1 host−guest ICs, double‐reciprocal plots of 1/▵A against 1/[CD] were plotted using the following equation (See supporting information Figure S3 , …”

Bitterness of fish protein hydrolysate and its debittering prospects

“…Sensory characteristics also indicated the decreased bitterness. Caso et al () investigated the inclusion properties of aromatic amino acids by complexing with β‐CD in model peptides using nuclear magnetic resonance (NMR). Internal cavity of CD was suitable for formation of complexes with aromatic/hydrophobic compound.…”