Premium
Conformation of amylose–iodine–iodide complex in aqueous solution
Author(s) -
Handa Takashi,
Yajima Hirofumi
Publication year - 1981
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1981.360201003
Subject(s) - chemistry , amylose , iodide , aqueous solution , iodine , persistence length , scattering , anisotropy , saturation (graph theory) , light scattering , crystallography , intrinsic viscosity , analytical chemistry (journal) , molecule , inorganic chemistry , chromatography , optics , organic chemistry , physics , polymer , mathematics , combinatorics , starch
Abstract The conformational characteristics of the amylose–iodine–iodide complex in aqueous solution, particularly for a rapidly mixed system, were studied by resonance polarized scattering measurements using a He‐Ne laser at low concentrations of the complex and by viscosity measurements at high concentrations of the complex. For the scattering measurements, the following results were obtained: the depolarization ratios ρ u and ρ v showed a pronounced increase with the degree of saturation of the bound iodine ( q ) in amylose, depending on KI concentration. At q ≃ 0.7, the increase in these values appeared to be suppressed. However, the ρ h value was approximately 1, irrespective of q . Additionally, the dissymmetry Z decreased appreciably with increasing q . The conformational change of the complex with q was characterized by the changes in the contour and persistence lengths of the chain and in the optical anisotropy of the scattering segments, which were obtained from numerical computations based on the polarized scattering equation for a wormlike‐chain model with a restriction by the entropy force of the chain. The viscosity of the complex solution decreased with increasing q ; above q ≃ 0.7 it increased strikingly. The conformational change of the complex with q was characterized by the change in exponent α in the Houwink‐Mark‐Sakurada equation [η] = KM α . It was concluded that the iodine‐saturated complex has the characteristics of a rod, regardless of the complex concentration.