文献类型：期刊文献

中文题名：3种离子强度下pH值对罗非鱼肌球蛋白溶解度及分子构象的影响

英文题名：Effect of pH on tilapia myosin solubility and conformation under three ionic strength solutions

作者：付苇娅[1];周春霞[1,2];朱潘红[1];郑惠娜[1,2];洪鹏志[1,2];杨萍[1,2]

机构：[1]广东海洋大学食品科技学院广东省水产品加工与安全重点实验室,广东湛江524088;[2]广东海洋大学深圳研究院,广东深圳518120

年份：2017

卷号：43

期号：9

起止页码：64

中文期刊名：食品与发酵工业

外文期刊名：Food and Fermentation Industries

收录：CSTPCD、、北大核心2014、CSCD2017_2018、北大核心、CSCD

基金：国家自然科学基金项目(31201389);广东省教育厅科技创新项目(2013KJCX0098);广东省省部产学研合作专项(2013A090100009)

语种：中文

中文关键词：罗非鱼肌球蛋白;pH值;离子强度;去折叠;溶解度;构象

外文关键词：tilapia myosin ; pH ; ionic strength ; unfolding; solubility; conformation

中文摘要：研究了3种离子强度下,不同pH值(2.0~12.0)对罗非鱼(Oreochromis niloticus)肌球蛋白溶解性、表面疏水性、SDS-PAGE及α-螺旋含量的影响。结果表明,在实验范围内,离子强度增大使肌球蛋白等电点向酸性方向偏移,在低离子强度(1 mmol/L KCl)、生理离子强度(150 mmol/L KCl)及高离子强度(600 mmol/L KCl)条件下,其溶解度最小的pH值分别为5.5、5.0和4.5,极端酸性(pH 2.0)和碱性(pH 11.0~12.0)条件下,肌球蛋白溶解度较高(>80%);在中性和高离子强度条件下,分子表面疏水性低,α-螺旋含量高,稳定性较好;酸诱导去折叠过程中,在等电点附近表面疏水性较低,在偏离等电点的酸性条件下,表面疏水性增加,而极端酸性条件下展开的肌球蛋白分子可能会发生折叠,分子降解及静电相互作用导致溶解度增大;碱诱导去折叠过程中,表面疏水性随pH值的升高而增加,肌球蛋白重链通过二硫键形成聚合物;在中性、碱性和极端酸性条件下,α-螺旋含量随着盐浓度的增加而增大,高盐对肌球蛋白的二级结构有保护作用。总体分析,在高盐浓度和极端碱性条件下,肌球蛋白呈现"熔球态"构象。

外文摘要：Effect of various pH （2.0 - 12.0） on solubility of tilapia myosin and surface hydrophobicity, SDSPAGE and α-helix contents of tilapia myosin were investigated at three ionic strength levels. Results showed that, in the experimental range, with increasing of ionic strength, the isoelectric point of myosin was shifted to acidic pH. In low ionic strength （1 mmol/L KCl）, physiological ionic strength （150 mmol/L KCl） and high ionic strength （600 mmol/L KCl） solution, the pH of the minimum solubilities of myosin was 5.5, 5.0 and 4.5 respectively. At extreme acid （pH 2.0） and alkali （pH 11.0 - 12.0） condition, the solubility of myosin was higher than 80%. Under the neutral and high ionic strength, surface hydrophobicity was low and α-helix content was high and stability of myosin was good. During acid-induced refolding process, lower surface hydrophobicity was observed near the isoelectric point, and surface hydrophobicity increased under the acid condition of deviating from the isoelectric point. However, unfolded myosin might refold partly under extreme acidic conditions, and molecular degradation and electrostatic inter- actions could lead to the high solubility. During alkali-induced refolding process, the surface hydrophobicity increased with the rising of pH value, the macro-molecular polymer was formed through disulfide bonding between myosin heavy chains. In neutral pH condition, alkaline and extreme acidic conditions, α-helix content increased with the increase of salt concentration, and therefore high salt could protect the secondary structure of myosin. All above results indicated that myosin molecule could be unfolded to an intermediate sate similar to ＂molten globule＂ at extreme alkali and high salt condition.