Amylose conformational transitions in binary DMSO/water mixtures

Cheetham, Norman W.H.; Tao, Leping

doi:10.1016/s0144-8617(97)00151-3

Cited by 42 publications

(42 citation statements)

References 19 publications

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“…When amy ose forms a complex the loose helix is forced into a tighter helical conformation by the complexing agent. In contrast to Banks & Greenwood (1971) Cheetham & Tao (1997 have shown [using the changes in chemical shifts of 13C NMR (nuclear magnetic resonance), optical rotation and limiting viSCOSity measurements] that amylose conformation in 100% DMSO is helical rather than a random coil. With the addition of water, the intramolecular hydrogen bonding In amylose (when amylose is in DMSO) is gradually replaced by amylose -water intermolecular hydrogen bonds (amylose I DMSO I water), leading to conformational changes.…”

Section: Amylosementioning

confidence: 90%

“…However, conflicting hypothesis still exists concerning the molecular conformation of amylose in aqueous solution (Banks & Greenwood, 1971;Senior & Hamori, 1973;Cheetham & Tao, 1997). Banks & Greenwood (1971) proposed three model conformations for amylose in aqueous solution (Fig 2.3 a-c).…”

Section: Amylosementioning

confidence: 99%

“…Further decrease in OM SO (66.6 to 33.3%) causes conformational change from loose helix -+ random coil [Cheetham & Tao, 1997] Amyfose in solution presents two features which are important in the functionality of starch based products; namely the ability to form indusion complexes with desirable ligands and the ability to form interchain associations inpolysaceharidechainsleadingtogelationorprecipitation.…”

Section: Amylosementioning

confidence: 99%

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The effect of hydroxypropylation on the structure and physicochemical properties of native, defatted and heat-moisture treated potato starches

Perera

Hoover

Martı́n

1997

Food Research International

116

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Native potato starch was physically modified by heat-moisture treatment (1WC, 16h, 30% moisture) and defatting (75%. n-propanol water, 7h). The changes in structure and physicochemical properties on heat-moisture treatment and defatting were monitored by scanning eleclron microscopy (SEM), X-ray diffraction, differential scanning calorimetry (OSC), Brabender viscosities, swelling fador (SF) and amylose leaching (AML). SEM showed that neither defatting nor heat-moisture treatment altered the size, shape or the surface appearance of the native starch granule. Heat-moisture treatment decreased Xray diffraction intensities and altered the 'B' type X-ray diffraction pattern to 'A+B'. The clecrease in X-ray intensities on heat-moisture treatment is indicative of aystallite disruption and/or rearrangement of double helices. The gelatinization enthalpy (aH), Brabender viscosity (at 95°C), SF and AML decreased on heat-moisture treatment. whereas gelatinization transition temperatures (GTT), and thermal stability inaeased. Defatting inaeased the Xray diffraction intensities and altered the X-ray pattern from 'B' to 'A+B'. The increased X-ray intensities on defatting is indicative of interactions between amylose -amylose (AM-AM), amylopectin -amylopectin (AMP-AMP) and amylose -amylopectin (AM-AMP) chains. These interactions in tum, increased

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Section: Amylosementioning

confidence: 90%

Section: Amylosementioning

confidence: 99%

Section: Amylosementioning

confidence: 99%

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The effect of hydroxypropylation on the structure and physicochemical properties of native, defatted and heat-moisture treated potato starches

Perera

Hoover

Martı́n

1997

Food Research International

116

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“…At pH > 13 the hydroxyl groups on the glucose residues become negatively charged and the molecule expands to its largest volume. In neutral water solution amylose obtains a random coil [146,147], an extended coil, a random coil with extended helical segments [148][149][150], or a wormlike helical conformation [151][152][153]-interpretation of experimental data are diverse. Nevertheless, amylose is unstable in aqueous solutions, especially in pure water, and forms double-helices that readily precipitate.…”

Section: Helical Conformationmentioning

confidence: 99%

Understanding Starch Structure: Recent Progress

Bertoft¹

2017

Agronomy

523

299

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Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species, their internal structures have remarkably similar architecture, consisting of growth rings, blocklets, and crystalline and amorphous lamellae. The basic components of starch granules are two polyglucans, namely amylose and amylopectin. The molecular structure of amylose is comparatively simple as it consists of glucose residues connected through α-(1,4)-linkages to long chains with a few α-(1,6)-branches. Amylopectin, which is the major component, has the same basic structure, but it has considerably shorter chains and a lot of α-(1,6)-branches. This results in a very complex, three-dimensional structure, the nature of which remains uncertain. Several models of the amylopectin structure have been suggested through the years, and in this review two models are described, namely the "cluster model" and the "building block backbone model". The structure of the starch granules is discussed in light of both models.

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“…The oxygen atom of a DMSO molecule can interact with water through H-bonding [10] with the continuum percolation transition in aqueous DMSO solutions with the percolation threshold of 12-15 wt.% of DMSO. A number of studies have been carried out over the years to understand the conformational properties of linear amylose [10][11][12][13][14] (Table 3) and branched amylopectin [14][15][16][17], in water and DMSO mixtures. The authors determined that the temperature and time of the dissolution have substantial influence on the weight average molecular mass, radius of gyration and the dispersion of the polysaccharide chains in the solution.…”

Section: Starch Polysaccharides and Osmotic Properties Of Its Pastesmentioning

confidence: 99%

Osmotic Properties of Polysaccharides Solutions

Kruk¹,

Pancerz²,

Ptaszek³

2017

Solubility of Polysaccharides

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Osmotic properties of polysaccharides' solutions and associated biopolymer-solvent and biopolymer-biopolymer type interaction are very important from a technological point of view. The knowledge of osmotic properties of these systems provides the basis to appropriate use of polysaccharides having comply with the relevant technology functions, impart the appropriate texture and forming the sensory properties of the final product. Furthermore, an important issue is the effect of time on the osmotic properties of polysaccharides', because with time, the aforementioned effects may change. Membrane osmometry is one of the methods used in the studies of synthetic polymers to determine their average molecular mass and the degree of interaction between a polymer and a solvent. This method is successfully applied in the case of biopolymers that include polysaccharides. The existence of the osmotic pressure, formed by diffusion of solvent molecules through a semi-permeable membrane, is the basis of this method. Analysis and interpretation of osmometric research results is based on the van't Hoff equation dependency of the concentration. The second virial coefficient obtained based on this relation allows characterisation of biopolymer-solvent interactions, and thus biopolymer tendency to solvation. The third virial coefficient provides information on mutual interactions between the biopolymer molecules, as well as its tendency to aggregate.

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Amylose conformational transitions in binary DMSO/water mixtures

Cited by 42 publications

References 19 publications

The effect of hydroxypropylation on the structure and physicochemical properties of native, defatted and heat-moisture treated potato starches

The effect of hydroxypropylation on the structure and physicochemical properties of native, defatted and heat-moisture treated potato starches

Understanding Starch Structure: Recent Progress

Osmotic Properties of Polysaccharides Solutions

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