Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama VI Rd., Phayathai, Bangkok 10400, Thailand.
J Biosci Bioeng. 2011 Jun;111(6):628-34. doi: 10.1016/j.jbiosc.2011.01.013. Epub 2011 Feb 26.
Non-rubber components present in natural rubber (NR) latex, such as proteins and phospholipids, are presumed to be distributed in the serum fraction as well as surrounding the rubber particle surface. The phospholipid-protein layers covering the rubber particle surface are especially interesting due to their ability to enhance the colloidal stability of NR latex. In this study, we have characterized the components surrounding the NR particle surface and investigated their role in the colloidal stability of NR particles. Proteins from the cream fraction were proteolytically removed from the NR latex and compare to those from the serum fractions using SDS-polyacrylamide gel electrophoresis revealing that both fractions contained similar proteins in certain molecular weights such as 14.5, 25 and 27 kDa. Phospholipids removed from latex by treatment with NaOH were analyzed using (1)H-NMR spectroscopy and several major signals were assignable to -(CH(2))(n)-, -CH(2)OP, -CH(2)OC═O and -OCH(2)CH(2)NH-. These signals are important evidence that indicates phospholipids associate with the rubber chain. The colloidal behavior of rubber lattices before and after removal of protein-lipid membrane was evaluated by zeta potential analysis and scanning electron microscope (SEM). The lowest zeta potential value of NR particles was observed at pH 10, consequently leading to the highest stability of rubber particles. Additionally, SEM micrographs clearly displayed a gray ring near the particle surface corresponding to the protein-lipid membrane layer.
天然胶乳（NR）中的非橡胶成分，如蛋白质和磷脂，据推测分布在血清部分以及橡胶颗粒表面周围。覆盖橡胶颗粒表面的磷脂-蛋白质层特别有趣，因为它们能够增强 NR 胶乳的胶体稳定性。在这项研究中，我们对 NR 颗粒表面周围的成分进行了表征，并研究了它们在 NR 颗粒胶体稳定性中的作用。通过蛋白酶解从 NR 胶乳中去除乳脂部分的蛋白质，并与血清部分的蛋白质进行 SDS-聚丙烯酰胺凝胶电泳比较，结果表明这两个部分在某些分子量（如 14.5、25 和 27 kDa）都含有相似的蛋白质。用 NaOH 处理从胶乳中去除的磷脂用 (1)H-NMR 光谱进行分析，几个主要信号可归因于 -(CH(2))(n)-、-CH(2)OP、-CH(2)OC═O 和 -OCH(2)CH(2)NH-。这些信号是磷脂与橡胶链结合的重要证据。通过zeta 电位分析和扫描电子显微镜（SEM）评估去除蛋白-脂膜前后橡胶晶格的胶体行为。NR 颗粒的 zeta 电位值在 pH 10 时最低，因此导致橡胶颗粒的稳定性最高。此外，SEM 显微照片清楚地显示了颗粒表面附近的灰色环，对应于蛋白-脂膜层。
