Conformational transitions of schizophyllan in aqueous alkaline solution

Kitamura, Shinichi; Hirano, Takashi; Takeo, Ken’ichi; Fukada, Harumi; Takahashi, Katsutada; Falch, Berit H.; Stokke, Bjørn T.

doi:10.1002/(sici)1097-0282(199609)39:3<407::aid-bip12>3.0.co;2-8

Cited by 56 publications

(63 citation statements)

References 33 publications

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“…4). Previous studies reported that concentrations of NaOH greater than 0.24 M were required to convert triplehelix glucans to random coils (19,27), which subsequently would form single helices after removing NaOH (16). FRET would not occur if there was actual strand separation (random coil conformers) due to the relatively large distance between the donor and the acceptor probes.…”

Section: Resultsmentioning

confidence: 99%

“…The degree of strand opening depends on the concentration of NaOH used. This structure better explains the observation that the M r of native and NaOH-treated SPG is the same (13,19). Identification of a partially opened triple-helix is difficult because most spectroscopic methods cannot distinguish between a closed and a partially opened triple-helix.…”

Section: Discussionmentioning

confidence: 99%

“…Aketagawa et al (18) suggested that treatment of SPG with NaOH causes the triple-helix to form single chains which rap-idly convert to a single helix followed by gradual reversion to the triple-helix (18). This mechanism implies that immediately after treatment with NaOH the M r should be one-third of the untreated glucan, however, experimental evidence has shown that denatured SPG has the same M r as untreated SPG (13,19). An alternative explanation that is consistent with the observations regarding M r would be that NaOH treatment results in a partially opened of the triple-helix rather than completed strand separation (Fig.…”

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Observation of a Partially Opened Triple-helix Conformation in 1→3-β-Glucan by Fluorescence Resonance Energy Transfer Spectroscopy

Young¹,

Dong²,

Jacobs³

2000

Journal of Biological Chemistry

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This study used fluorescence resonance energy transfer (FRET) spectroscopy as an indirect method to investigate the effect of NaOH treatment on the conformation of a triple-helix (133)-␤-D-glucan and then evaluated the effect of conformation on biological activity. Previous studies have suggested that treatment of the triple-helix glucans with NaOH produces single-helix conformers. FRET spectra of the triple-helix glucan, laminarin, doubly labeled with 1-aminopyrene as donor probe and fluorescein-5-isothiocyanate as acceptor probe attached at the reducing end, showed that a partially opened triplehelix conformer was formed on treatment with NaOH. Increasing degrees of strand opening was associated with increasing concentrations of NaOH. Based on these observations we propose that a partially opened triplehelix rather than a single helix, is formed by treating the triple-helix glucans with NaOH. After neutralizing the NaOH, changes in FRET indicated that the partially opened conformer gradually reverts to the triple-helix over 8 days. Laminarian was stabilized at different degrees of partial opening and its biological activity examined using the Limulus amebocyte lysate assay and nitric oxide production by alveolar macrophage. Both Limulus amebocyte lysate activity and nitric oxide production were related to the degree of opening of the triple-helix. Partially open conformers were more biologically active than the intact triple-helix.(133)-␤-D-Glucans have been shown to systemically enhance the immune system, resulting in antitumor, antibacterial, and wound healing activities (1). Differences in these activities are thought to be related to three factors: molecular conformation, the degree of branching, and the molecular weight (M r ) (2). Studies have shown that high M r (100,000 -200,000 g/mol) glucans with a degree of branching of 0.20 -0.33 are most active (2), however, data describing the effects of molecular conformation on biological activity are less clear. This is in part due to the lack of adequate methodology to characterize the tertiary structure of glucans.Most spectroscopic techniques only provide data about the secondary structure of glucans. Methods such as solid state 13 C NMR spectroscopy (3) or multi-angle laser-light scattering (4) have had some success in relating the tertiary structure of glucans to their conformation based biological activity, however, their use is limited by availability, cost, and efficacy for evaluating glucan structure in solution. A direct observation technique, such as x-ray crystallography would assist in understanding glucan structure and its biological relevance; however, it is difficult to crystallize glucans and only a limited number of these studies have been done (5-7).Fluorescence resonance energy transfer (FRET) 1 is a phenomenon of non-radioactive energy transfer over relatively long distances that has been used to characterize the spatial relationship of donor-and acceptor-labeled molecules in biological systems (8). If a system contains two fluorophores an...

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Observation of a Partially Opened Triple-helix Conformation in 1→3-β-Glucan by Fluorescence Resonance Energy Transfer Spectroscopy

Young¹,

Dong²,

Jacobs³

2000

Journal of Biological Chemistry

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“…This helix-coil transition, which is a cooperative process, is commonly referred as 'denaturation' (Cantor & Schimmel, 1980;Sletmoen & Stokke, 2008). Denaturation of ␤-1,3-D-glucans has been reported to occur in alkaline solutions (>0.25 M NaOH) (Bo, Milas, & Rinaudo, 1987;Kitamura et al, 1996;Tabata, Ito, Kojima, Kawabata, & Misaki, 1981), in dimethylsulfoxide (DMSO; water weight fraction W H < 0.13) (Kitamura & Kuge, 1989;Norisuye et al, 1980;Sato, Norisuye, & Fujita, 1981;, or when increasing the temperature above the triplex melting temperature, Tm = 135 • C Yanaki, Tabata, & Kojima, 1985).…”

Section: Introductionmentioning

confidence: 99%

Effects of thermal, alkaline and ultrasonic treatments on scleroglucan stability and flow behavior

Viñarta

Delgado

Figueroa

et al. 2013

Carbohydrate Polymers

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“…The triplex structure of these nonionic, high molecular weight samples are stable over a broad range of temperatures in aqueous solution at physiological pH. They can, however, be forced to undergo a strand-separation transition (denaturation) when the temperature is increased above 135°C, 10 -12 when in highly alkaline solutions (pH Ͼ 12) 13,14 or when the water weight fraction in mixed water-dimethylsulfoxide (DMSO) solvents is below 0.13. 12,15 The immunological properties of scleroglucan and other (1 33)-␤-D-glucans, e.g., lentinan and schizophyllan, 16 -18 are one important application area where the conformation of the molecules adopted in aqueous solution affects their efficiency, and ultimately their clinical use.…”

Section: Introductionmentioning

confidence: 99%

Macromolecular triplex zipping observed in derivatives of fungal (1 ? 3)-?-D-glucan by electron and atomic force microscopy

2001

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Conformational transitions of schizophyllan in aqueous alkaline solution

Cited by 56 publications

References 33 publications

Observation of a Partially Opened Triple-helix Conformation in 1→3-β-Glucan by Fluorescence Resonance Energy Transfer Spectroscopy

Observation of a Partially Opened Triple-helix Conformation in 1→3-β-Glucan by Fluorescence Resonance Energy Transfer Spectroscopy

Effects of thermal, alkaline and ultrasonic treatments on scleroglucan stability and flow behavior

Macromolecular triplex zipping observed in derivatives of fungal (1 ? 3)-?-D-glucan by electron and atomic force microscopy

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