Structural Stability of V-Amylose Helices in Water-DMSO Mixtures Analyzed by Molecular Dynamics

Abstract

Computational techniques have been employed to fundamentally understand the behavior of helically structured amylose in water/DMSO mixtures. Using a computationally generated amylose helix of 55 glucose residues, we have investigated the time-dependent behavior of intra- and intermolecular hydrogen bonds, particularly between O2 and O3 of adjacent glucose molecules and between O6 and neighboring O2 and O3 groups. The helix character was defined by the total number of residually existing hydrogen bonds. Our results parallel the experimental finding that increasing the percentage of DMSO results in increasing helical stability. It can be shown that O6-O2/O3 hydrogen bonds are preferentially lost when the helix starts to unfold to a finally resulting random coil structure. While water is small enough to interact with every hydroxyl group at the helix surface and finally penetrate the helix coil, DMSO can initially only form single hydrogen bonds to part of the OH groups of the amylose molecule, thereby allowing a longer conservation of intramolecular hydrogen bonds that are necessary to maintain the helix. However, given a long enough time for interaction, the helical structure of amylose is lost in water as well as in DMSO, yielding a random orientation of the glucose strand.

Molecular dynamics studies of amylose plasticized with Brazilian Cerrado oils: part I

“…As observed in experimental data and corroborated further by MD studies, inter-and intra-molecular interactions play a major role on the molecular behavior of complex systems comprised by natural plasticizers and polysaccharides [12,[17][18][19]21] . In fact, they are essential for the rational design of high performance biomaterials as well as to predict its properties.…”

“…They found that strong hydrogen bonding was essential for cohesion of the amylose/glycerol model, which was further corroborated by experimental data (X-ray diffraction, tensile strength and water uptake), probed with starch/glycerol cast films. Tusch et al [18] observed that at certain simulation times the helix character of a single helical amylose chain (55 monomeric units) in water/DMSO mixtures was stabilized after increasing the DMSO concentration, since DMSO helps to preserve intramolecular hydrogen bonds in starch. Their findings were in consonance with NMR data.…”

“…In fact, they are essential for the rational design of high performance biomaterials as well as to predict its properties. Most of MD studies were limited to a single and short poly-glucose chains, mainly because larger and more complex systems would demand for longer simulation times and even more expensive computational instrumentation [17][18][19]21] .…”

Amylose folding under the influence of lipids

“…11,[20][21][22] However, previous MD studies of amylose have mainly dealt with small amylose fragments in water or studies of V-amylose in low polarity solvents. [23][24][25] The object of the present study was to deepen the understanding of the structure and formation of V-amylose inclusion complexes in view of its anticipated use as a delivery system of long chain fatty acids and other nutraceuticals. To that aim, we consider a short amylose fragment, and simulate its structure and dynamics in the presence of either dipalmitoyl-phosphatidylcholine (diC 16 -PC) or glycerol monooleate (GMO) in aqueous solution.…”

Relationship between intrinsic viscosity, thermal and retrogradation properties of amylose and amylopectin

“…Recently, many researchers have reported various properties of amylose such as structural conformation and stability in solvents (Nakanishi et al 1993;Shimada et al 2000;Radosta et al 2001;Tusch et al 2011), conformational transitions (Cheetham & Tao 1997), crystallisation and crystal structure (Takahashi et al 2004;Creek et al 2006;Popov et al 2009;Montesanti et al 2010), amylose complexes (Hulleman et al 1996;Ozcan & Jackson 2002;Nuessli et al 2003;Ciesielski & Tomasik 2004;Cardoso et al 2007;Nishiyama et al 2010), gel microstructure and textural properties (Torres et al 1978;Leloup et al 1992) and amylose gel physical network (Lay & Delmas 1998). Whereas, research on the properties of amylopectin was focused on its structural and retrogradation properties (Manners & Matheson 1981;Manners 1989;Paredes-Lopez et al 1994), crystallinity of amylopectin films and network formation (Putaux et al 2000;Myllarinen et al 2002), and amylopectin complexes (Ciesielski & Tomasik 2004).…”