Probing macromolecular architectures of nanosized cyclic structures of (1→3)-β-d-glucans by AFM and SEC-MALLS

Sletmoen, Marit; Christensen, Bjørn E.; Stokke, Bjørn Torger

doi:10.1016/j.carres.2005.01.026

Cited by 32 publications

(44 citation statements)

References 29 publications

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“…30 This is close to the predicted value for triple-helical structures of scleroglucan, being equal to 2150 g mol À1 nm…”

supporting

confidence: 67%

“…Scleroglucan of the latter M w has also previously been shown to give a large fraction of circular structures upon renaturation and chromatograms of such samples are previously published. 29,30 Based on imaging techniques the circular structures have been shown to elute in the last part of the elution profile, i.e., from 17.5 to 21.0 mL in the experimental set up used in the present studies. The elution profile was determined using both a RI and an UV detector.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have concluded that circular molecules elute in the interval 17.5-21.0 mL, whereas linear structures elute in the interval 11.5-14.5 mL. 30 For notational convenience, the terms circular and linear are therefore adopted in the following for the fraction eluting in the intervals 17.5-21.0 mL, and before 14.5 mL, respectively. Thus, the relative fraction of linear and circular molecules can be determined from the area under the chromatogram corresponding to these two fractions.…”

Section: Resultsmentioning

confidence: 99%

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Structural properties of polyC–scleroglucan complexes

Sletmoen¹,

Stokke²

2005

Biopolymers

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Successive changes of solvent conditions can be used to dissociate and reassociate the triple-helical structure of (1,3)-beta-D-glucans. Ultramicroscopic techniques have revealed a blend of circular and other structures following renaturation. When this solvent exchange process is carried out in the presence of certain polynucleotides, the process creates a novel macromolecular complex. Here, we use size exclusion chromatography (SEC) to study such (1,3)-beta-D-glucan-polynucleotide complexes. Online multi-angle laser-light scattering (MALLS) and refractive index (RI) detectors allowed determination of molecular weight and radius of gyration of the molecules. An ultraviolet (UV) detector allowed specific detection of the polynucleotide. The poly-cytidylic acid (poly C) shifted to coelution with the linear fraction of the scleroglucan following the renaturation of poly C-scleroglucan blends, indicating that poly C is incorporated in linear, but not in circular, structures of scleroglucan. This conclusion was consistent with AFM topographs that revealed a decreased fraction of circular structures upon addition of poly C during the renaturation process. The combined information about radius of gyration (R(g)) and molecular weight (M(w)) allowed us to conclude that the poly C-scleroglucan complexes are more dense and have a higher persistence length than linear scleroglucan triple helixes. The experimentally determined mass per unit length was used as a basis for elucidating possible molecular arrangements within the poly C-scleroglucan complex.

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“…30 This is close to the predicted value for triple-helical structures of scleroglucan, being equal to 2150 g mol À1 nm…”

supporting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Structural properties of polyC–scleroglucan complexes

Sletmoen¹,

Stokke²

2005

Biopolymers

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“…On the assumption that -(1,3)-glucans are able to exist as a triple helix in water, which can be denatured by adding dimethylsulfoxyde (DMSO), and that the resulting random coil can be reformed by adding water [61], it has been hypothesized that -(1,3)-glucans could be very interesting candidates for complexing helical nucleic acids. Such a concept was demonstrated by the teams of Shinkai and Sakurai.…”

Section: Synthesis Of -(13)-glucans and Deriva-tives Chemical Modulamentioning

confidence: 99%

Recent Progress in the Field of β-(1,3)-Glucans and New Applications

Descroix¹,

Ferrières²,

Jamois³

et al. 2006

MRMC

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Beta-(1,3)-glucans are widely distributed within microorganisms or seaweeds in which they act as membrane components or for energy storage, respectively. Since these glucans are not biosynthesized by mammals, they are likely to activate the immune system of their host. Since the discovery of their positive involvement as immunomodulator agents, numerous studies were published all around the glycosciences. These works deal with purification procedures, analytical chemistry, synthetic processes, chemical modification of the natural polysaccharides, determination of their physicochemical properties, and assessment of their biological and medicinal effects through in vitro and in vivo studies. This article aims at presenting some recent results linked to beta-(1,3)-glucans through two closely connected points of view, i.e. biology and chemistry. Biological aspects will be focused more particularly on discovery of some receptors present on immunocompetent cells and scope and limitations of chemical synthesis and/or modifications will be described. Moreover, this paper will also introduce some new chemo-enzymatic synthetic methods using wild-type or mutant glycosidases and will be extended to novel opportunities of applications of beta-(1,3)-glucans in nanotechnology resulting from a better understanding of their self-assembling propensity in aqueous media.

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“…[8][9][10] It has been reported that many (1!3)-(1!6)-b-D D-glucans adopt ordered helical conformations in aqueous solution. 11,12 A strong alkaline environment can induce the denaturation of such helical structures by breaking the intra-and intermolecular hydrogen bonds, leading to reduced aqueous viscosity. 13 As shown in Figure 3, significant reduction of intrinsic viscosity [g] was observed as NaOH concentration increases from 0 to 0.2 M, reflecting a continuous denaturation process of Table 1.…”

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confidence: 99%