【摘要】 利用ThT荧光分析法、透射电子显微镜和圆二色光谱检测αs1-酪蛋白形成淀粉样纤维沉淀(Fibril)的动力学过程,优化了其形成条件,研究了Fibril形成的影响因素.实验结果表明,αs1-酪蛋白在65℃高温下,pH=5～5.4的范围内,加热144 h以上,可以形成Fibril.在此过程中,αs1-酪蛋白的二级结构由α螺旋构象向β折叠构象转变.甘油磷酸胆碱D6PC可以显著地促进αs1-酪蛋白Fibril的形成,并呈浓度依赖性,说明一定条件下蛋白质可能与细胞膜的磷脂之间存在相互作用,从而导致酪蛋白二级构象的转变.硫酸肝素对αs1-酪蛋白形成Fibril无影响,说明硫酸肝素对蛋白质二级构象的影响作用因蛋白质的不同而不同,与不同蛋白质的Fibril形成机制相关.更多还原

【Abstract】 αs1-Casein is the major protein in milk and has a molecular chaperone action.With the interest in that,whether κ-and αs2-casein can form amyloid fibrils or not,we investigated amyloid fibril formation from αs1-casein by means of ThT assay,transmission electron microscopy and circular dichroism(CD) spectra.The results show that amyloid fibrils formed from αs1-casein at pH=5.0—5.4 and 65 ℃ under heating for 144 h.The CD spectra show that the structure of αs1-casein has changed from α-helical to β sheet core,which are the special structure characters of fibrils.Lipids of D6PC promoted amyloid fibril formation from αs1-casein in the concentration of 0.3 and 1 mmol/L.Heparin sulphate did not influence the fibril formation from αs1-casein in the test.It is concluded that although αs1-casein has the effects of molecular chaperon,but it could still form fibrils under harsh conditions.Lipids can influence amyloid fibril formation from αs1-casein,depanding on concentration.It suggests that there is relationship between lipid in membrane and amyloid fibril formation.The results are helpful to exploring the mechanism of fibril formation from αs1-casein.更多还原