Structural properties associated with the emulsifying functionality of parvalbumin isoforms

用Sephadex G-75柱层析从鲤鱼肌浆蛋白组分中分离出细小蛋白(PA)。当PA组分与三油酸脂分散时，其乳化性能优于其他肌浆蛋白(Sp-P)组分。当蛋白质浓度较低时，PA组分的脂肪结合能力较高。PA组分的表面疏水性明显低于Sp-P组分。通过DEAE-Sephacel层析，得到了PA的三种异构体(a，b，c)，并对洗脱时间进行了排序。在PA异构体(c&gt；b&gt；a)中，c亚型的乳化活性最高。在80ﾟC以上加热，异构体分子间形成分子间二硫键，引发二聚反应，二聚反应对乳化活性有一定影响。EDTA还导致PA异构体的乳化活性、表面疏水性和静电性质(等电点)发生变化。与Ca~(2+)~(2+)有关的PA的结构和静电状态的变化可能会显著影响乳化性能。

Parvalbumin (PA) was separated from carp sarcoplasmic protein fraction with Sephadex G-75 chromatography. When dispersed with triolein, PA fraction had superior emulsifying properties to the other sarcoplasmic protein (Sp-P) fraction. Fat-binding capacity of PA fraction was higher at lower protein concentration. Surface hydrophobicity of PA fraction was significantly less than Sp-P fraction. Superiority of emulsifying activity in PA was suggested to be independent of hydrophobicity.Three isoforms (a, b, c) of PA were obtained with DEAE-Sephacel chromatography in order of the elution time. Emulsifying activity of isoform c was the highest in the PA isoforms (c>b>a). Intermolecular disulfide bond was formed between the molecules of the isoforms to induce dimerization by heating above 80ﾟC.The dimerization somewhat affected the emulsifying activity. EDTA also led the PA isoforms to vary their emulsifying activity, surface hydrophobicity and electrostatic property (isoelectric point). Changes in the structural and electrostatic states of PA related to Ca^<2+> might have markedly affected the emulsifying properties.