Disordering of helix of oxidized L‐methionine containing copolypeptides

Abstract

The solid-state conformation of copolymers of oxidized L-methionine [~-Met(O)l with L-methionine (L-Met) and/or L-alanine (L-Ala) was studied by IR spectroscopy and circular dichroism (CD). The results from the IR spectra in the region of 900-330 cm-' are compared with data obtained by CD experiments. A film cast from the solution of a copolymer containing L-Met(0) had a new trough between 205 and 210 nm in the solid-state CD spectra and new IR absorption bands at 815 and 680 cm-', while oxidizing the film of an L-Met containing copolymer after casting did not induce a significant change in IR and CD spectra. It seems that the film cast from the solution of an L-Met(0) containing copolymer exhibits the feature of a random coil as well as of an a-helix. From the CD spectra of the film on immersion in water, it was deduced that the helix of the film became gradually disordered and hence the film was dissolved in water.

Oxidation‐Responsive Materials: Biological Rationale, State of the Art, Multiple Responsiveness, and Open Issues

“…Here we would like to emphasize a morphological consequence of Met oxidation in such typically highly ordered structures: the higher hydrophilicity of oxidized species is typically accompanied by a loss of order in their secondary structure. This was first shown by Aiba et al on poly(methionine) in the 1980s and later by Gellman et al. in the 1990s, using a peptide containing multiple Met residues, whose oxidation to both sulfoxide and sulfone determined a transition from α helix to β strand.…”

Selective Tuning of Elastin-like Polypeptide Properties via Methionine Oxidation

“…The lack of T t for low concentrations of ELP-M O -40 was likely due to increased water-solubility afforded by the sulfoxide groups as compared to thioether groups. 4,33,34 With T t values greater than those of ELP-M-40, but lower than those of ELP-M O -40 at identical concentrations, the sulfone derivative ELP-M O2 -40 (T t = 42 to 69°C, concentration = 25 to 1,250 μM) displayed intermediate temperature-dependent solubility compared to the other ELPs. Although sulfone groups have greater dipole moments compared to sulfoxides, the large dipoles of the sulfone groups can lead to sulfone−sulfone and sulfone−protein interactions, that can lead to decreased water solubility.…”

Homogeneous grafting reaction of vinyl pyrrolidone onto chitosan

“…Whereas chitin contains an acetmethod. [1][2][3] amide groups situated in the C-2 of the anhyCurrently, we are working on the grafting of droglucose ring, the presence of free amine groups vinyl monomers on polysaccharides, such as chiin chitosan enhances the solubility of this polysactin, pectin, and chitosan, where these polysacchacharide in dilute acids as compared with chitin. rides carry functional groups, such as amido, carIn spite of a rather wide range of applications boxyl, and amino, respectively.…”