tailieunhanh - Báo cáo khoa học: The oleic acid complexes of proteolytic fragments of a-lactalbumin display apoptotic activity

In this review, we first describe the mechanisms by which the epidermal growth factor receptor generates a Ca 2+ signal and, subsequently, we com-pile the available experimental evidence regarding the role that the Ca 2+ ⁄calmodulin complex, formed after the rise in cytosolic free Ca 2+ concentration, exerts on the receptor. | ỊFEBS Journal The oleic acid complexes of proteolytic fragments of a-lactalbumin display apoptotic activity Serena Tolin1 Giorgia De Franceschi1 Barbara Spolaore1 Erica Frare1 Marcella Canton2 Patrizia Polverino de Laureto1 and Angelo Fontana1 1 CRIBI Biotechnology Centre University of Padua Italy 2 Department of ExperimentalBiomedicalSciences University of Padua Italy Keywords apoptosis HAMLET oleic acid protein fragments a-lactalbumin Correspondence P. Polverino de Laureto CRIBI Biotechnology Centre University of Padua Viale G. Colombo 3 35121 Padua Italy Fax 39 049 827 6159 Tel 39 049 827 6157 E-mail Received 7 August 2009 revised 9 October 2009 accepted 27 October 2009 doi The complexes formed by partially folded human and bovine a-lactalbumin with oleic acid OA have been reported to display selective apoptotic activity against tumor cells. These complexes were named human HAMLET or bovine BAMLET alpha-lactalbumin made lethal to tumor cells. Here we analyzed the OA complexes formed by fragments of bovine a-lactalbumin obtained by limited proteolysis of the protein. Specifically the fragments investigated were 53-103 and the two-chain fragment species 1-40 53-123 and 1-40 104-123 these last being the N-terminal fragment 1-40 covalently linked via disulfide bridges to the C-terminal fragment 53-123 or 104-123. The OA complexes were obtained by mixing the fatty acid and the fragments in solution 10-fold and 15-fold molar excess of OA over protein fragment or by chromatography of the fragments loaded onto an OA-conditioned anion exchange column and salt-induced elution of the OA complexes. Upon binding to OA all fragments acquire an enhanced content of a-helical secondary structure. All OA complexes of the fragment species showed apoptotic activity for Jurkat tumor cells comparable to that displayed by the OA complex of the intact protein. We conclude that the entire sequence of the protein is .