tailieunhanh - Báo cáo khoa học: Protein dissection enhances the amyloidogenic properties of a-lactalbumin

a-lactalbumin (LA) in its molten globule (MG) state at low pH forms amyloid fibrils. Here, we have studied the aggregation propensities of LA derivatives characterized by a single peptide bond fission (1–40⁄41–123, named Th1-LA) or a deletion of a chain segment of 12 amino acid resi-dues located at the level of the b-subdomain of the native protein (1– 40⁄53–123, named desb-LA). We have also compared the early stages of the aggregation process of these LA derivatives with those of intact LA | iFEBS Journal Protein dissection enhances the amyloidogenic properties of a-lactalbumin Patrizia Polverino de Laureto1 Erica Frare1 Francesca Battaglia1 Maria F. Mossuto1 Vladimir N. Uversky2 3 4 and Angelo Fontana1 1 CRIBI Biotechnology Centre University of Padua Italy 2 Institute for BiologicalInstrumentation Russian Academy of Sciences Pushchino Russia 3 Department of Biochemistry and Molecular Biology Medical School Indiana University Indianapolis IN USA 4 Molecular Kinetics Inc. Indianapolis IN USA Keywords amyloid a-lactalbumin circular dichroism infrared spectroscopy limited proteolysis molten globule protein aggregation Correspondence A. Fontana CRIBI Biotechnology Centre University of Padua Viale G. Colombo 3 35121 Padua Italy Fax 39 49 827 6159 Tel 39 49 827 6156 E-mail Received 21 December 2004 revised 23 February 2005 accepted 2 March 2005 doi a-lactalbumin LA in its molten globule MG state at low pH forms amyloid fibrils. Here we have studied the aggregation propensities of LA derivatives characterized by a single peptide bond fission 1-40 41-123 named Th1-LA or a deletion of a chain segment of 12 amino acid residues located at the level of the b-subdomain of the native protein 140 53-123 named desb-LA . We have also compared the early stages of the aggregation process of these LA derivatives with those of intact LA. Th1-LA and desb-LA aggregate at pH much faster than the intact protein and form long and well-ordered fibrils. Furthermore in contrast to intact LA the LA derivatives form regular fibrils also at neutral pH even if at much reduced rate. In acidic solution Th1-LA and desb-LA adopt a MG state which appears to be similar to that of intact LA as given by spectroscopic criteria. At neutral pH both Th1-LA and desb-LA are able to bind the hydrophobic dye 1-anilinonaphtalene-8-sulfonate thus indicating the presence of exposed hydrophobic patches. It is concluded that nicked Th1-LA and .