ABSTRACT Isoelectric precipitation was used to produce protein isolates (>90% protein contents) from three edible vegetable leaves. Amaranth (ALI), eggplant (ELI) and fluted pumpkin (FLI) leaf protein were isolated to study their conformational structures. Intrinsic fluorescence indicated a loose structural conformation for ELI at all the pH values, whereas FLI and ALI had more compact structures at pH 3.0 and pH 9.0. The surface hydrophobicity showed a greater distribution of hydrophobic amino acid groups of the protein isolates at the basic than the acidic regions. The SDS-PAGE results showed that the leaf isolates had similar polypeptide bonds characterized by 20, 25, 40 and 200 kDa and some distinct bands above 200 kDa. The ELI formed emulsions with significantly (p < .05) smallest oil droplet sizes (<3.3 µm) when compared to FLI and ALI. However, foaming capacity was mostly pH-dependent with significantly (p < .05) higher values at pH 7.0 and 9.0. The leaf protein isolates may be considered as potential functional food ingredients.

中文翻译：

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食用植物叶分离蛋白结构和功能特性的比较研究

摘要 等电沉淀用于从三种可食用植物叶中生产蛋白质分离物（> 90% 蛋白质含量）。分离苋菜 (ALI)、茄子 (ELI) 和南瓜 (FLI) 叶蛋白以研究它们的构象结构。内在荧光表明 ELI 在所有 pH 值下都具有松散的结构构象，而 FLI 和 ALI 在 pH 3.0 和 pH 9.0 下具有更紧凑的结构。表面疏水性表明蛋白质分离物的疏水性氨基酸基团在碱性区域比酸性区域分布更大。SDS-PAGE 结果表明，叶分离物具有相似的多肽键，其特征在于 20、25、40 和 200 kDa 以及一些超过 200 kDa 的不同条带。ELI 形成的乳液具有显着 (p < .05) 最小的油滴尺寸 (<3. 3 µm) 与 FLI 和 ALI 相比。然而，起泡能力主要取决于 pH 值，在 pH 7.0 和 9.0 时具有显着更高的值 (p < .05)。叶蛋白分离物可被视为潜在的功能性食品成分。