Effects of Lipids and Heparin Sulphate on Formation of Amyloid Fibril from αs1-Casein

alpha(s1)-Casein is the major protein in milk and has a molecular chaperone action. With the interest in that, whether kappa-and alpha(s2)-casein can form amyloid fibrils or not, we investigated amyloid fibril formation from alpha(s1)-casein by means of ThT assay, transmission electron microscopy and circular dichroism(CD) spectra. The results show that amyloid fibrils formed from art alpha(s1)-casein at pH=5. 0-5. 4 and 65 degrees C under heating for 144 h. The CD spectra show that the structure of alpha(s1)-casein has changed from alpha-helical to beta sheet core, which are the special structure characters of fibrils. Lipids of D6PC promoted amyloid fibril formation from alpha(s1)-casein in the concentration of 0. 3 and 1 mmol/L. Heparin sulphate did not influence the fibril formation from alpha(s1)-casein in the test. It is concluded that although alpha(s1)-casein has the effects of molecular chaperon, but it could still form fibrils under harsh conditions. Lipids can influence amyloid fibril formation from alpha(s1)-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 alpha(s1)-casein.