Conformational studies of alanine‐rich peptide using CD and FTIR spectroscopy

Abstract

The circular dichroism (CD) and Fourier transform infrared (FTIR) methods were applied to the conformational studies of alanine-rich peptide Ac-K-[A]11-KGGY-NH2 (where K is lysine, A is alanine, G is glycine and Y is tyrozyne) in water, methanol (MeOH) and trifluoroethanol (TFE). The analysis of CD-spectra of the peptide in water at different concentrations revealed that the secondary structure content depends on the peptide concentration and pH of the solution. The increase of the peptide concentration causes a decrease of alpha-helix content and, simultaneously, an increase of beta-sheet structure, while the unordered structure is the predominant one. Additional elements are discovered in MeOH and TFE but alpha-helix and beta-turns predominate. Moreover, in these solutions the percentage content of the secondary structure does not depend on the temperature. FTIR measurements, carried out at higher peptide concentration (about one order of magnitude) than these CD measurements mentioned above, revealed that in water solution the solid state beta-sheet, and aggregated structures, dominate. However, in TFE the most abundant are alpha-helix and beta-turns structures. The thioflavine T assay showed the tendency of the studied peptide for aggregate.

Screening of antimicrobial compound from the sea slug <i>Armina babai</i>

“…The FT-IR spectroscopy is complementary to the CDspectroscopy method according to the conformational studies of peptides and proteins (Bagińska et al, 2008). Therefore, sometimes they may be used simultaneously.…”

PEG-Poly(l-alanine) Thermogel As a 3D Scaffold of Bone-Marrow-Derived Mesenchymal Stem Cells

“…The PEG‐PA was synthesized by the ring‐opening polymerization of the N ‐carboxy anhydrides of l‐alanine, where α‐amino‐ω‐methoxy PEG was used as an initiator . The α‐amino‐ω‐methoxy PEG (5.0 g, 5.0 mmole) was dissolved in anhydrous toluene (70 mL) and the residual water was removed by azeotropic distillation to a final volume of about 10 mL.…”

Targeted Delivery with Peptidomimetic Conjugated Self-Assembled Nanoparticles

“…For example, CD spectral analysis of alanine-rich peptide Ac-K-[A] 11 -KGGY-NH 2 demonstrated that the α-helix content of the self-assembled peptide depended on peptide concentration in water and secondary structure was independent of temperature (76). FTIR spectra of the same peptide in water revealed that the β-sheet structure dominated at higher concentrations (76). The interaction of the polymer chain with conjugated peptide can be studied by X-ray reflectivity as well as CD and FTIR (77,78).…”

“…The secondary structure of the synthesized peptide and peptide-polymer conjugate can be characterized by circular dichroism (CD) and Fourier Transform Infrared Spectrometry (FTIR) (76). CD and FTIR spectral range of 200-300 nm and 1,500-1,800 cm −1 , respectively, are utilized for analysis of secondary structures (76).…”

“…CD and FTIR spectral range of 200-300 nm and 1,500-1,800 cm −1 , respectively, are utilized for analysis of secondary structures (76). For example, CD spectral analysis of alanine-rich peptide Ac-K-[A] 11 -KGGY-NH 2 demonstrated that the α-helix content of the self-assembled peptide depended on peptide concentration in water and secondary structure was independent of temperature (76). FTIR spectra of the same peptide in water revealed that the β-sheet structure dominated at higher concentrations (76).…”