Structural properties associated with the emulsifying functionality of parvalbumin isoforms

用SephadexG-75柱层析法从鲤鱼肌浆蛋白中分离出小清蛋白（PA）。当用三油酸甘油酯分散时，PA组分具有优于其它肌浆蛋白（Sp-P）组分的上级乳化性能。PA组分的脂肪结合能力在较低的蛋白质浓度下较高。PA组分的表面疏水性显著低于Sp-P组分。用DEAE-Sephacel柱层析，按洗脱时间的先后顺序得到了3种异构体（a，B，c）。异构体c的乳化活性在PA异构体中最高（c>B>a）。在80 ℃以上加热时，异构体分子之间形成分子间二硫键，从而诱导二聚化。二聚化在一定程度上影响乳化活性。EDTA还导致PA异构体改变其乳化活性、表面疏水性和静电性质（等电点）。与Ca^<2+>有关的PA结构和静电状态的变化可能显著影响其乳化性能。

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.