Liu Wei, Prausnitz John M, Blanch Harvey W
Chemical Engineering Department, University of California, Berkeley, 94720, USA.
Biomacromolecules. 2004 Sep-Oct;5(5):1818-23. doi: 10.1021/bm049841e.
Peptide LYS (11-36), derived from the beta-sheet region of T4 lysozyme, forms an amyloid fibril in aqueous trifluoroethanol (TFE) at elevated temperature. The peptide has a moderate alpha-helix content in 20 and 50% (v/v) TFE solution; large quantities of fibrils were formed after incubation at 55 degrees C for 2 weeks as monitored by a thioflavin T fluorescence assay. No fibrils were observed when the peptide initially existed predominantly as a random coil or as a complete alpha helix. Our results suggest that a moderate amount of alpha helix and random coil present in the peptide initially facilitates the fibril-formation process, but a high alpha-helix content inhibits fibril formation. Transmission electron microscopy revealed several types of fibril morphologies at different TFE concentrations. The fibrils were highly twisted and consisted of interleaved protofilaments in 50% TFE, while smooth and flat ribbonlike fibrils were found in 20% TFE. In 50% TFE, the fibril growth rate of LYS (11-36) was found to depend strongly on peptide concentration and seeding but was insensitive to solution pH and ionic strength.
源自T4溶菌酶β折叠区域的肽LYS (11 - 36)，在高温下于三氟乙醇(TFE)水溶液中形成淀粉样纤维。该肽在20%和50%（v/v）的TFE溶液中具有适度的α螺旋含量；通过硫黄素T荧光测定法监测，在55摄氏度孵育2周后形成了大量纤维。当肽最初主要以无规卷曲或完整的α螺旋形式存在时，未观察到纤维。我们的结果表明，肽中最初存在的适量α螺旋和无规卷曲有助于纤维形成过程，但高α螺旋含量会抑制纤维形成。透射电子显微镜揭示了在不同TFE浓度下几种类型的纤维形态。在50% TFE中，纤维高度扭曲，由交错的原纤维组成，而在20% TFE中发现了光滑扁平的带状纤维。在50% TFE中，发现LYS (11 - 36)的纤维生长速率强烈依赖于肽浓度和接种，但对溶液pH值和离子强度不敏感。
