学術雑誌論文

学術雑誌論文

text

Journal of Physical Chemistry B. 2012, 116(42), p. 12714-12720

Side-chain-dependent helical conformation of amylose alkylcarbamates: Amylose tris(ethylcarbamate) and amylose tris(n-hexylcarbamate)

American Chemical Society

英語

text

2012-10-05

https://doi.org/10.1021/jp307998t

Terao K., Maeda F., Oyamada K., et al. Side-chain-dependent helical conformation of amylose alkylcarbamates: Amylose tris(ethylcarbamate) and amylose tris(n-hexylcarbamate). Journal of Physical Chemistry B, 116(42), 12714-12720, October 5, 2012. Copyright © 2012, American Chemical Society. https://doi.org/10.1021/jp307998t.

Eight amylose tris(ethylcarbamate) (ATEC) samples ranging in the weight-average molar mass Mw from 1.0 - 104 to 1.1 - 106 g mol-1 and five amylose tris(n-hexylcarbamate) (ATHC) samples of which Mw varies from 4.9 - 104 to 2.2 - 106 g mol-1 have been prepared from enzymatically synthesized amylose samples having narrow dispersity indices and no branching. Small-angle angle X-ray scattering (SAXS), light scattering, viscometry, and infrared (IR) absorption measurements were carried out for their dilute solutions, that is, ATEC in tetrahydrofuran (THF), 2-methoxyethanol (2ME), methanol (MeOH), and ATHC in THF and 1-propanol (1PrOH) to determine M w, particle scattering functions, intrinsic viscosities, and IR spectra. SAXS and viscosity measurements were also made on ATEC in d- and l-ethyl lactates. The data were analyzed in terms of the wormlike cylinder model to estimate the helix pitch (or contour length) per residue h and the Kuhn segment length λ-1 (stiffness parameter, twice the persistence length). Both ATEC and ATHC have large λ-1 in THF, that is, 33 and 75 nm, respectively, and smaller λ-1 were obtained in alcohols, indicating that they have rigid helical conformation stabilized by intramolecular hydrogen bonds in THF. On the contrary, the helical structure estimated from the h value significantly depends on the alkyl side groups in a complex fashion, that is, h = 0.36 nm for ATEC, h = 0.29 nm for ATHC, and h = 0.26 nm for amylose tris(n-butylcarbamate) (ATBC). This is likely related to the bulkiness of side groups packed inside the amylosic helices. The solvent dependence of h, λ-1, and the fraction fhyd of intramolecular hydrogen bonds for ATEC can be explained by a current model as is the case with ATBC [ Terao, K.; Macromolecules 2010, 43, 1061 ], in which each contour point along the chain takes loose helical and rigid helical sequences independently. © 2012 American Chemical Society.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Journal of Physical Chemistry B, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/jp307998t.

81805

Side-chain-dependent helical conformation of amylose alkylcarbamates: Amylose tris(ethylcarbamate) and amylose tris(n-hexylcarbamate)

American Chemical Society

英語

2012-10-05

Journal of Physical Chemistry B

116

42

12714

12720

https://doi.org/10.1021/jp307998t

https://hdl.handle.net/11094/81805