Conformation of carboxylated schizophyllan in aqueous solution

Yoshiba, Kazuto; Sato, Takahiro; Osumi, Takaaki; Ulset, Ann-Sissel Teialeret; Christensen, Bjørn E.

doi:10.1016/j.carbpol.2015.07.049

Cited by 16 publications

(20 citation statements)

References 29 publications

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“…It is known that the Sclg triplex is stable in water solution up to 135 ∘ C. Furthermore, triplex stability decreases by adding DMSO to the water solution, or by increasing the alkalinity, with a triplex unfolding observed close to pH 13 [6][7][8]. Very similar behaviours have been reported for other (1 → 3)--Dglucans with 1,6-linked branches, from a structural point of view, closely related with Sclg [9][10][11][12]. The reversibility of the triplex to ss-Sclg transition is still under discussion; however, in many experimental conditions, the native triplex does not form again after a denaturation process occurred [13][14][15].…”

Section: Introductionsupporting

confidence: 66%

Relative Stability of the Scleroglucan Triple-Helix and Single Strand: an Insight from Computational and Experimental Techniques

Bocchinfuso

Meisina

Conflitti

et al. 2016

Zeitschrift Für Physikalische Chemie

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Scleroglucan (Sclg) is a polysaccharide that exhibits a triple helix conformation (triplex), both in aqueous solution and in the solid state, which is lost in DMSO solution, at high temperature and at high pH values. The triplex conformation is characterized by a high rigidity, responsible of Sclg peculiar properties. Although the relative stability of triplex and single strand has already been investigated, different structural details are still missing. In the present study, we analyse the structural properties and the factors stabilizing the single chain and the triple helix of Sclg in different conditions. To this end, we simulated both systems in water and in DMSO. The triple helix has been also simulated in the presence of chemical damages on one of the three strands (to reproduce in silico the effect of sonication) or by inducing a partial unfolding of the triplex structure. The computational results have been compared with experimental evidences in which the triplex denaturation, at alkaline pH values, has been followed by monitoring the UV and CD spectra of Congo red, used as a probe molecule. Our results indicate that sonication breaks the Sclg chains without appreciably changing the stability of the other tracts of triple helix. The simulated perturbed or partially unfolded triplexes show a clear tendency to form less Unauthenticated Download Date | 6/23/16 1:58 PM 2 | G. Bocchinfuso et al. ordered aggregates. Finally, our simulations put in evidence an important role of the hydrophobic interactions both in the triplex stability and in the aggregation processes observed after induced denaturation.

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Section: Introductionsupporting

confidence: 66%

Relative Stability of the Scleroglucan Triple-Helix and Single Strand: an Insight from Computational and Experimental Techniques

Bocchinfuso

Meisina

Conflitti

et al. 2016

Zeitschrift Für Physikalische Chemie

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“…We can summarize present results of SEC-MALS, DSC, and optical rotation (OR) measurements performed on the order-disorder transition of sclerox, as follows: Firstly, the sclerox samples have almost the same M before and after the oxidations. In contrast, a dissociation or aggregation of the trimer would largely affect Mw and the molar mass distribution (Yoshiba et al, 2015). However, these are almost unchanged for present samples by the chemical modification, which is attributed to the low DS.…”

Section: Analysis Of the Transition Curvementioning

confidence: 64%

“…The sonicated sample was purified by the fractional reprecipitation in the aqueous solution with ethanol to obtain middle fraction of each sample (SPG-1, SPG-2). The carboxylation of the sample was performed in an aqueous solution according to previous study on sclerox (Yoshiba et al, 2015). In brief, 30 mM aqueous sodium periodate (Wako Pure Chemical Industries Ltd., Osaka, Japan) was dropped into 120 ml of 0.1wt% aqueous schizophyllan containing 13.3 ml of 1-propanol to prepare different degree of oxidation of the samples.…”

Section: Experimental Schizophyllan and Carboxylated Schizophyllan Samentioning

confidence: 99%

“…Since the order-disorder transition of schizophyllan is characteristic to the triple helical conformation (Kitamura & Kuge, 1989), it is necessary to investigate both of the molecular conformation and the transition behavior after the chemical modification. From conformational aspects for sclerox, we showed that a sclerox at low DS remains a trimer in 0.1 M NaCl (Yoshiba, Sato, Osumi, Ulset, Christensen, 2015). However, size-exclusion chromatography combined with multi-angle light scattering detection (SEC-MALS) indicated the global conformation of the trimer is different from the triple helix of parent schizophyllan by becoming more flexible and extended after the carboxylation.…”

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confidence: 95%

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Effects of carboxylation of the side chains on the order-disorder transition in aqueous solution of schizophyllan, a triple helical polysaccharide

Yoshiba

Okamoto

Dobashi

et al. 2017

Carbohydrate Polymers

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Schizophyllan and scleroglucan are water-soluble polysaccharides having repeating units consisting of three β-1,3-linked glucose residues in the main chain and a single β-1,6-linked glucose residue as the side chain. This polysaccharide dissolves as a triple helix in an aqueous solution and shows a cooperative order-disorder transition between the side chain and solvent molecules while retaining the triple helical conformation. Periodate and subsequent chlorite oxidations selectively modify the side chain glucose to provide the corresponding dicarboxylate units. Optical rotation measurements and differential scanning calorimetry were performed on carboxylated schizophyllan/scleroglucan ('sclerox') samples to investigate the effects of the degree of carboxylation on the order-disorder transition in deuterium oxide with 0.1M NaCl. The transition curves for the sclerox samples are strongly dependent on the degree of carboxylation. The modified side chains cannot take the ordered structure, resulting in a reduction of the transition enthalpy. The transition temperature for carboxylated schizophyllan becomes lowered and the transition curve broadens with increasing the degree of carboxylation. The permanent disordered units are included in a trimer by the carboxylation to inhibit a long sequence of the ordered units.

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“…In this case, the carboxylated side chains cannot take the ordered state, so that the transition temperature is lowered, and the transition enthalpy is decreased with increasing DS. However, the molecular conformation of the sclerox trimer is affected by carboxylation . The chain stiffness becomes flexible, and the helical pitch is extended, which may hinder a long sequence of the ordered structure.…”

Section: Discussionmentioning

confidence: 99%

Conformation and cooperative order‐disorder transition in aqueous solutions of β‐1,3‐d‐glucan with different degree of branching varied by the Smith degradation

et al. 2019

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β‐1,3‐d‐glucan with different degrees of branching were obtained by selectively and gradually removing side chains from schizophyllan, a water‐soluble triple helical polysaccharide, using the Smith degradation. Size exclusion chromatography combined with a multi‐angle light scattering detection was performed in aqueous 0.1 M NaCl. The degree of branching decreased after the Smith degradation, while the molar mass distributions were almost unchanged. The molecular conformation of the Smith‐degraded β‐1,3‐d‐glucan was analyzed on the basis of the molar mass dependency of the radius gyration, and found to be comparable to the original triple helix of schizophyllan. Differential scanning calorimetry in deuterium oxide–hexadeuterodimethylsulfoxide mixtures was performed to investigate the effects of the degree of branching on the cooperative order‐disorder transition. Removal of side chains affects both the transition temperature and transition enthalpy. The ordered structure is formed by the residual side chains in the triplex unit, so that the linear cooperative system of the triplex is maintained after the Smith degradation.

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Conformation of carboxylated schizophyllan in aqueous solution

Cited by 16 publications

References 29 publications

Relative Stability of the Scleroglucan Triple-Helix and Single Strand: an Insight from Computational and Experimental Techniques

Relative Stability of the Scleroglucan Triple-Helix and Single Strand: an Insight from Computational and Experimental Techniques

Effects of carboxylation of the side chains on the order-disorder transition in aqueous solution of schizophyllan, a triple helical polysaccharide

Conformation and cooperative order‐disorder transition in aqueous solutions of β‐1,3‐d‐glucan with different degree of branching varied by the Smith degradation

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