Morphological and structural studies of poly(gly‐gly‐ala)

Abstract

SynopsisThe ultrastrrict,ural morphology and x-ray and electron diffract,ion of poly(Gly-Cr1y-Ala) have been studied. The polymer has two forms; the first, form I possesses a superfolded cross-p striictiire, long fibers of which show some twisting and intert,wining. Form I1 precipitates in a less dist.irict. fibroiis form from aqueous solut,ion. The x-ray diffraction and orient,ed electron diffraction dat,a suggest th%t, form I1 isba polyglyciAie I1 helix situated iii a monoclinic cell with dimensions a = I;.% A, b = 22.0 A, c = 9.42 A, and p = YO0. Combined with the morphological evidence it appears likely that form I1 is also in ail antiparallel superfolded array.

Supramolecular Amyloid-like Assembly of the Polypeptide Sequence Coded by Exon 30 of Human Tropoelastin

“…The deconvoluted amide II region of EX30 fibers (Fig. 5) shows two components at 1516 cm Ϫ1 as well as at 1558 cm Ϫ1 that are considered representative of the presence of ␤-sheet conformation (45,46). The band at 1542 cm Ϫ1 could be tentatively assigned to the unordered component.…”

A study of conformational stability of polyglycine and poly(L-alanine), and polyglycine/poly(L-alanine) blends in the solid state by13C cross-polarization/magic angle spinning NMR

“…The conformation of PG was converted to 3 1 -helix structure by precipitation from an aqueous lithium bromide solution. [13][14][15][16] Poly(Lalanine) (MW 23600) with the ␣-helix form was purchased from Sigma Chemical Co. The conformation of these polypeptides was checked by 13 C CP/MAS nmr.…”

“…By using PLA/PG blend systems, such conformational change may provide useful knowledge about conformational stability under the balance of intermolecular hydrogen-bonding interactions between PLA and PG, and also under the balance of intramolecular and intermolecular hydrogen bonding interactions. As nmr methodology for elucidating the conformational stability in the PLA/PG systems the conformation-dependent 13 Cnmr chemical shift for polypeptides in the solid state will be able to be used in this work, which has been demonstrated in a series of our research works as described below. This is the motivation of the present study.…”

“…We have elucidated that 13 C-nmr chemical shifts of a number of polypeptides and proteins in the solid state as determined by the CP/MAS (cross-polarization/magic angle spinning) method are significantly displaced depending on their particular conformations such as ␣-helix, ␤-sheet, 3 1 -helix, and -helix. 8 -12 It has been clarified that PG takes the ␤-sheet and 3 1 -helix forms and PLA takes the right-handed ␣-helix and ␤-sheet forms in the solid state, and (Ala, Gly) n copolymers take the right-handed ␣-helix, ␤-sheet and 3 1 -helix forms in the solid state as obtained by changing a composition ratio or solvent treatment.…”

“…8 -12 It has been clarified that PG takes the ␤-sheet and 3 1 -helix forms and PLA takes the right-handed ␣-helix and ␤-sheet forms in the solid state, and (Ala, Gly) n copolymers take the right-handed ␣-helix, ␤-sheet and 3 1 -helix forms in the solid state as obtained by changing a composition ratio or solvent treatment. [13][14][15][16] From such a background, in this work, we aim to prepare PG/PLA blend samples with various mixture ratios and to elucidate the conformational stability of PG and PLA in PG/PLA blends by 13 C CP/MAS nmr and T 1H experiments.…”