Structural changes and dynamic rheological properties of sarcoplasmic proteins subjected to pH-shift method.
Structural changes and dynamic rheological properties of sarcoplasmic proteins subjected to pH-shift method.
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DOI：
10.1021/jf903219u
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发表时间：
2010-04
影响因子：
6.1
通讯作者：
P. Tadpitchayangkoon;J. W. Park;S. G. Mayer;J. Yongsawatdigul
中科院分区：
文献类型：
--
作者：
P. Tadpitchayangkoon;J. W. Park;S. G. Mayer;J. Yongsawatdigul
研究了不同ph位移作用下条纹鲶鱼（Pangasius hypophthalmus）肌浆蛋白的结构变化和动态流变学特性。酸提取的肌浆蛋白的等电沉淀导致其在水中的溶解度最低。肌浆蛋白经过极酸和极碱提取后展开，暴露出色氨酸和脂肪残基。α -螺旋结构在酸性提取后转化为β -薄片，而碱性处理不会扰乱肌浆蛋白的α -螺旋结构。在极端pH萃取条件下，二硫化物形成、酪氨酸残基氢键和疏水相互作用发生。与碱性处理相比，酸性提取诱导肌浆蛋白变性和聚集的程度更大。在等电沉淀过程中，通过脂肪和芳香残基形成疏水相互作用。肌浆蛋白经过等电沉淀和中和后部分重新折叠。通过碱性ph转移过程制备的肌浆蛋白在45.10℃时容易聚集形成凝胶，而在酸处理的肌浆蛋白中观察到更高的热变性温度（约80℃）和凝胶点（约78℃）。提取、沉淀和中和的pH条件对肌浆蛋白的结构变化有很大的影响，导致了不同的热流变特性和动态流变特性。
Structural changes and dynamic rheological properties of sarcoplasmic proteins from striped catfish ( Pangasius hypophthalmus ) treated by various pH-shift processes were investigated. Isoelectric precipitation of acid-extracted sarcoplasmic proteins led to the lowest solubility in water. Sarcoplasmic proteins were unfolded after extremely acidic and alkaline extraction, exposing tryptophan and aliphatic residues. The alpha-helical structure was converted to beta-sheet following acidic extraction, whereas alkaline treatment did not disturb the alpha-helical structure of sarcoplasmic proteins. Disulfide formation, hydrogen bonding via tyrosine residues, and hydrophobic interactions occurred under extreme pH extraction. Acidic extraction induced denaturation and aggregation of sarcoplasmic proteins to a greater extent than did alkaline treatment. Hydrophobic interactions via aliphatic and aromatic residues were formed during isoelectric precipitation. Sarcoplasmic proteins were partially refolded after isoelectric precipitation followed by neutralization. Sarcoplasmic proteins prepared from an alkaline pH-shift process readily aggregated to form a gel at 45.10 degrees C, whereas higher thermal denaturation temperatures (>80 degrees C) and gel points ( approximately 78 degrees C) were observed in acid-treated sarcoplasmic proteins. The pH condition used for extraction, precipitation, and neutralization greatly affected structural changes of sarcoplasmic proteins, leading to different thermal and dynamic rheological properties.