Jaindl Martina, Popp Marianne
Department of Biomolecular Structural Chemistry, University of Vienna, A-1030 Vienna, Austria.
Biochem Biophys Res Commun. 2006 Jun 30;345(2):761-5. doi: 10.1016/j.bbrc.2006.04.144. Epub 2006 May 3.
The accumulation of cyclitols in plants is a widespread response that provides protection against various environmental stresses. The capacity of myo-Inositol, pinitol, quercitol, and other compatible solutes (i.e., sorbitol, proline, and glycinebetaine) to protect proteins against thermally induced denaturation and deactivation was examined. Enzymatic activity measurements of L-glutamine synthetase from Escherichia coli and Hordeum vulgare showed that the presence of cyclitols during heat treatment resulted in a significantly higher percentage of residual activity. CD spectroscopy experiments were used to study thermal stabilities of protein secondary structures upon the addition of myo-Inositol, pinitol, and glucose. 0.4 M myo-Inositol was observed to raise the melting temperature (Tm) of GS from E. coli by 3.9 degrees C and MDH from pig heart by 3.4 degrees C, respectively. Pinitol showed an increase in Tm of MDH by 3.8 degrees C, whereas glucose was not effective. Our results show a great potential of stabilizing proteins by the addition of cyclitols.
环醇类物质在植物中的积累是一种广泛存在的反应，可提供针对各种环境胁迫的保护作用。研究了肌醇、松醇、槲皮醇和其他相容性溶质（即山梨醇、脯氨酸和甘氨酸甜菜碱）保护蛋白质免受热诱导变性和失活的能力。对来自大肠杆菌和大麦的L-谷氨酰胺合成酶的酶活性测量表明，热处理期间环醇类物质的存在导致残余活性的百分比显著更高。圆二色光谱实验用于研究添加肌醇、松醇和葡萄糖后蛋白质二级结构的热稳定性。观察到0.4 M肌醇分别使大肠杆菌谷氨酰胺合成酶（GS）的解链温度（Tm）提高3.9℃，使猪心肌苹果酸脱氢酶（MDH）的Tm提高3.4℃。松醇使MDH的Tm升高3.8℃，而葡萄糖则无效。我们的结果表明添加环醇类物质在稳定蛋白质方面具有巨大潜力。
