Single Crystals of V-Amylose Complexed with α-Naphthol

Abstract

Lamellar square single crystals of V-amylose were obtained by adding alpha-naphthol to metastable dilute aqueous solutions of synthetic amylose chains with an average degree of polymerization of 100. The morphology and structure of the crystals were studied using low-dose transmission electron microscopy including high-resolution imaging, as well as electron and X-ray diffraction. The crystals are crystallized in a tetragonal P4(1)2(1)2 or P4(3)2(1)2 space group with unit cell parameters, calculated from X-ray diffraction data, a = b = 2.2844 nm (+/-0.0005) and c = 0.7806 nm (+/-0.001), implying the presence of two amylose chains per unit cell. High-resolution lattice images of the crystals confirmed that the amylose chains were crystallized as 8-fold helices corresponding to the repeat of four maltosyl units.

V-amylose Structural Characteristics, Methods of Preparation, Significance, and Potential Applications

“…(4,6,46,48) In space, the single helices are organized into the standard orthogonal space group 8 P2 1 2 1 2 1 arrangement and may have up to 4 or 16 water molecules in the interhelical space within each crystal unit cell for V a and V h , respectively ( Figure 2). (4,6,10) The 8-fold helices (V8) on the other hand, may occur as tetragonal P41212 or P43212 space group with unit cell parameters a = b = 2.2844 nm and c = 0.7806 nm (49) . The helical structure of the V-amylose was recently discussed by Putseys et al (50) and Putaux et al.…”

Helical Conformation in Crystalline Inclusion Complexes of V‐Amylose: A Historical Perspective

“…[45] So far, the strongest evidence of an 8-fold helix has been provided by Cardoso et al who published high-resolution lattice images, showing a 8 subunit projection along the helical axis. [61] A brief mention of a 9-fold helix in V a-naphthol crystals can be found in a paper by Jane and Robyt but the authors admit that their data are insufficient to support this hypothesis. [62] The Structure of Amylose V isopropanol Crystals In order to propose a conclusive threedimensional model for the complexes of the V isopropanol family, we have prepared V isopropanol single crystals and recorded their electron diffraction patterns.…”

Amylose folding under the influence of lipids

“…3 In fact different arrangements are observed in the unit cell for V-amylose crystals, depending on the exact crystallization conditions. 4 Amylose can also fold under the influence of other compounds, such as surfactants and lipids. The amylose-lipid complexes are important in the food industry 5 (e.g., emulsifying starch) and are suitable nanocapsules for controlled release of lipids.…”