Yamamoto Kaori, Yagi Hisashi, Ozawa Daisaku, Sasahara Kenji, Naiki Hironobu, Goto Yuji
Institute for Protein Research, Osaka University, and CREST, Japan Science and Technology Agency, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan.
J Mol Biol. 2008 Feb 8;376(1):258-68. doi: 10.1016/j.jmb.2007.12.002. Epub 2007 Dec 7.
Dialysis-related amyloidosis frequently develops in patients undergoing long-term hemodialysis, in which the major component of fibrils is beta(2)-microglobulin (beta2-m). To prevent the disease, it is important to stop the formation of fibrils. beta2-m has one disulfide bond, which stabilizes the native structure, and amyloid fibrils. Here, the effects of reductants (i.e., dithiothreitol and cysteine) on the formation of beta2-m amyloid fibrils were examined at neutral pH. Fibrils were generated by three methods: seed-dependent, ultrasonication-induced, and salt-and-heat-induced fibrillation. Thioflavin T fluorescence, electron microscopy, and far-UV circular dichroism revealed that the addition of reductants significantly inhibits seed-dependent and ultrasonication-induced fibrillation. For salt-and-heat-induced fibrillation, where the solution of beta2-m was strongly agitated, formation of amyloid fibrils was markedly reduced in the presence of reductants, although a small number of fibrils formed even after the reduction of the disulfide bond. The results suggest that reductants such as cysteine and dithiothreitol would be useful for preventing the formation of beta2-m amyloid fibrils under physiological conditions.
透析相关淀粉样变性常见于长期接受血液透析的患者，其中淀粉样纤维的主要成分是β2-微球蛋白（β2-m）。为预防该疾病，阻止纤维形成很重要。β2-m有一个二硫键，可稳定天然结构和淀粉样纤维。在此，研究了还原剂（即二硫苏糖醇和半胱氨酸）在中性pH条件下对β2-m淀粉样纤维形成的影响。纤维通过三种方法生成：种子依赖型、超声诱导型和盐热诱导型纤维化。硫黄素T荧光、电子显微镜和远紫外圆二色性显示，添加还原剂可显著抑制种子依赖型和超声诱导型纤维化。对于盐热诱导型纤维化，即β2-m溶液剧烈搅拌的情况，在存在还原剂时淀粉样纤维的形成明显减少，尽管二硫键还原后仍形成少量纤维。结果表明，半胱氨酸和二硫苏糖醇等还原剂在生理条件下对预防β2-m淀粉样纤维的形成可能有用。
