Furuki Takao, Shimizu Tempei, Chakrabortee Sohini, Yamakawa Kentarou, Hatanaka Rie, Takahashi Tsuyoshi, Kikawada Takahiro, Okuda Takashi, Mihara Hisakazu, Tunnacliffe Alan, Sakurai Minoru
Center for Biological Resources and Informatics, Tokyo Institute of Technology, Yokohama, Japan.
Biochim Biophys Acta. 2012 Jul;1824(7):891-7. doi: 10.1016/j.bbapap.2012.04.013. Epub 2012 May 8.
Group 3 late embryogenesis abundant (G3LEA) proteins have amino acid sequences with characteristic 11-mer motifs and are known to reduce aggregation of proteins during dehydration. Previously, we clarified the structural and thermodynamic properties of the 11-mer repeating units in G3LEA proteins using synthetic peptides composed of two or four tandem repeats originating from an insect (Polypedilum vanderplanki), nematodes and plants. The purpose of the present study is to test the utility of such 22-mer peptides as protective reagents for aggregation-prone proteins. For lysozyme, desiccation-induced aggregation was abrogated by low molar ratios of a 22-mer peptide, PvLEA-22, derived from a P. vanderplanki G3LEA protein sequence. However, an unexpected behavior was noted for the milk protein, α-casein. On drying, the resultant aggregation was significantly suppressed in the presence of PvLEA-22 with its molar ratios>25 relative to α-casein. However, when the molar ratio was <10, aggregation occurred on addition of PvLEA-22 to aqueous solutions of α-casein. Other peptides derived from nematode, plant and randomized G3LEA protein sequences gave similar results. Such an anomalous solubility change in α-casein was shown to be due to a pH shift to ca. 4, a value nearly equal to the isoelectric point (pI) of α-casein, when any of the 22-mer peptides was mixed. These results demonstrate that synthetic peptides derived from G3LEA protein sequences can reduce protein aggregation caused both by desiccation and, at high molar ratios, also by pH effects, and therefore have potential as stabilization reagents.
第3组晚期胚胎发生丰富（G3LEA）蛋白具有带有特征性11聚体基序的氨基酸序列，并且已知在脱水过程中可减少蛋白质的聚集。此前，我们使用由源自昆虫（摇蚊）、线虫和植物的两个或四个串联重复序列组成的合成肽，阐明了G3LEA蛋白中11聚体重复单元的结构和热力学性质。本研究的目的是测试此类22聚体肽作为易聚集蛋白保护剂的效用。对于溶菌酶，源自摇蚊G3LEA蛋白序列的22聚体肽PvLEA - 22以低摩尔比即可消除干燥诱导的聚集。然而，对于乳蛋白α-酪蛋白，观察到了意想不到的行为。干燥时，当PvLEA - 22与α-酪蛋白的摩尔比>25时，α-酪蛋白的聚集显著受到抑制。然而，当摩尔比<10时，向α-酪蛋白水溶液中添加PvLEA - 22会发生聚集。源自线虫、植物和随机G3LEA蛋白序列的其他肽也得到了类似结果。结果表明，当任何一种22聚体肽混合时，α-酪蛋白这种异常的溶解度变化是由于pH值转变至约4，该值几乎等于α-酪蛋白的等电点（pI）。这些结果表明，源自G3LEA蛋白序列的合成肽可减少由干燥以及高摩尔比时的pH效应引起的蛋白质聚集，因此具有作为稳定试剂的潜力。
