Removal of the side-chain glucose groups from schizophyllan improves the thermal stability of the polycytidylic acid complexes under the physiological conditions
✍ Scribed by Kazuya Koumoto; Ryouji Karinaga; Masami Mizu; Takahisa Anada; Kazuo Sakurai; Toyoki Kunitake; Seiji Shinkai
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2004
- Tongue
- English
- Weight
- 266 KB
- Volume
- 75
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
Thermal stabilization of the complex between polycytidylic acid [poly(C)] and the modified schizophyllan (SPG) whose hydrophilic side‐chain glucose groups are selectively removed utilizing mild Smith‐degradation has been investigated. With the decrease in the side‐chain glucose groups of schizophyllan, the complex with poly(C) can be considerably stabilized compared with unmodified SPG; for example, the T~m~ value after the removal of the side‐chain glucose groups from 33.3 (unmodified) to 1.0 is enhanced by 14°C. In addition, the thermal stabilization effect is even operative under the physiological conditions ([NaCl] = 0.15 mol dm^−3^). This effect is exerted owing to the construction of the hydrophobic atmosphere around the complex. Although schizophyllan lost the side‐chain glucose groups, it still kept the protection effect of the bound poly(C) chain against RNaseA‐mediated hydrolysis as observed for unmodified schizophyllan. The assessment of the cytotoxicity for A375:human malignant melanoma, and HL60:human promyelocytic leukemia revealed that the modified schizophyllan scarcely increases the cytotoxicity. These results indicate that the present modification for schizophyllan is of great significance in a viewpoint to develop the practical gene carriers operative even under the physiological conditions. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004