3 种方法提取的澳洲坚果蛋白功能性质与构象的关系

采用3?种蛋白提取方法从澳洲坚果脱脂粉中提取得到3?种分离蛋白，包括碱提酸沉澳洲坚果蛋白（alkaline extraction and acid precipitation extracted macademia protein isolate，MAPI）、三（羟甲基）氨基甲烷提取澳洲坚果蛋白（tris (hydroxymethyl) aminomethane extracted macademia protein isolate，MTPI）以及氯化钠提取澳洲坚果蛋白（sodium chloride extracted macadamia protein isolate，MSPI），并对其功能和构象进行比较研究。研究发现，在酸性pH值范围内MSPI比MAPI和MTPI有更高的溶解性，而在碱性pH值范围内恰好相反。MSPI比MAPI和MTPI具有更高的乳化活性指数。MAPI、MTPI和MSPI的蛋白质量分数分别为88.9%、80.3%和86.1%。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和氨基酸分析表明，3?种分离蛋白具有相似的条带分布和氨基酸组成，但它们的条带强度和氨基酸数量不同。此外，与MAPI和MTPI相比，MSPI具有较高的表面疏水性、荧光强度和较小的粒度。场发射扫描电子显微镜结果表明，MSPI比MAPI和MTPI具有更多的由不同大小球状结构组成的颗粒。

Comparison of Functional Properties of Macadamia (Macadamia integrifolia) Proteins Prepared by Three Different Methods Related to Their Conformation

Functional and conformational properties of three proteins from defatted macadamia kernel flour prepared by alkaline (MAPI), Tris-HCl (MTPI) and sodium chloride (MSPI) extraction methods were investigated. MSPI was found to have higher solubility than MAPI and MTPI in the acidic pH range, while the opposite was observed in the alkaline pH range. MSPI had an emulsifying activity index higher than that of MAPI and MTPI. The protein contents of MAPI, MTPI and MSPI were 88.9%, 80.3% and 86.1%, respectively. The three protein isolates had similar protein bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and similar amino acid composition except for differences in band intensities and amino acid contents. Furthermore, MSPI showed higher surface hydrophobicity and fluorescence intensity and smaller particle size than MAPI and MTPI. Field emission scanning electron microscopy (FE-SEM) results revealed that MSPI contained more spherical particles of different sizes as compared with MAPI and MTPI.