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

Abstract

Summary: Amylose forms V-type crystalline inclusion complexes with a large variety of small molecules. Several authors have proposed models for these complexes based on amylose single helices with 6, 7 and 8 glucosyl units per turn. However, so far, only a small number of crystal structures have been solved and several models are still hypothetical. We have recently shown that in the unit cell of such complex with isopropanol, the amylose molecules were organized in 7-fold left-handed helices, with isopropanol and water molecules located as guests both within and between the helices.

Single Crystals of V‐Amylose Complexed with Bicyclic Organic Compounds

“…V6 I (also called V h ), prepared for instance with ethanol or fatty acids, V6 II , prepared with n ‐butanol, and V6 III , prepared with glycerol, contain 6‐fold helices. The previously proposed occurrence of 7‐fold helices (V7 structure) has recently been demonstrated for complexes with 2‐propanol . Finally, a V8 structure has been reported for complexes with 1‐naphthol and quinoline …”

“…The amylose single helices are oriented perpendicular to the lamellae with a thickness, or folding length, of about 10 nm . The guest complexing agent is thought to be located inside the amylose helices, in‐between, or both …”

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

“…The helical structure of the V-amylose was recently discussed by Putseys et al (50) and Putaux et al. (51) from a historical perspective.…”

Characterization Methods for Starch-Based Materials: State of the Art and Perspectives

“…Native starch is typically complexed with lipids and displays six glucose unit turns. [100,101] The single helices form V-type crystallites while the double helices can produce A-or B-type crystallites. V-type crystallites involve lipid complexes.…”