在 pH 偏移法作用下肌浆蛋白的结构变化和动态流变特性。

Structural changes and dynamic rheological properties of sarcoplasmic proteins subjected to pH-shift method.

机构信息

School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand.

出版信息

J Agric Food Chem. 2010 Apr 14;58(7):4241-9. doi: 10.1021/jf903219u.

DOI:10.1021/jf903219u

PMID:20232914

Abstract

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.

摘要

研究了不同 pH 值转换过程处理的条纹鲶鱼（ Pangasius hypophthalmus ）肌浆蛋白的结构变化和动态流变特性。酸性提取的肌浆蛋白等电沉淀导致在水中的溶解度最低。极度酸性和碱性提取后，肌浆蛋白展开，暴露出色氨酸和脂肪族残基。酸性提取后，α-螺旋结构转化为β-折叠，而碱性处理不会干扰肌浆蛋白的α-螺旋结构。在极端 pH 值提取时，形成二硫键、通过酪氨酸残基形成氢键以及疏水相互作用。酸性提取比碱性处理更能引起肌浆蛋白的变性和聚集。通过脂肪族和芳香族残基形成疏水相互作用。等电沉淀后，肌浆蛋白部分复性，然后中和。从碱性 pH 值转换过程制备的肌浆蛋白在 45.10 度下容易聚集形成凝胶，而在酸性处理的肌浆蛋白中观察到更高的热变性温度（>80 度）和凝胶点（约 78 度）。提取、沉淀和中和过程中使用的 pH 值极大地影响了肌浆蛋白的结构变化，导致不同的热和动态流变特性。