| Abstract |
The aim of the present study is to investigate the effect of glycation on structur and functional properties of bovine serum albumin (BSA). Glucose and p-aminophenyl α-D-mannopyranoside were employed to modify -amino groups and carboxyl groups of BSA for preparation of AGE-BSA and Man-BSA, respectively. The results of mass analyses, HPLC, fluorescence and CD measurement indicated that glycation markedly changed physicochemical properties of BSA. Compared with AGE-BSA, Man-BSA had higher hydrophilicity. Fluorescence intensity of Man-BSA was lower than those of native BSA and AGE-BSA. The structural stability of Man-BSA was notably higher than that of BSA and AGE-BSA. The membrane-damaging activity, membrane perturbation effect and fusogenicity of glycated BSA on liposomes were further investigated using fluorescence measurement. In contrast to BSA and AGE-BSA, Man-BSA showed a notable membrane-damaging activity on liposomes, while the binding-affinity of these proteins for liposomes was similar. Noticeably, Man-BSA induced fusion of EYPC/ EYSM/Chol vesicles and membrane permeability of EYPC/EYSM vesicles. FTIR spectra showed that Man-BSA adopted distinct structure upon binding with EYPC/ EYSM/Chol and EYPC/EYSM vesicles. Likewise, Glc-BSA in which carboxyl groups were modified with p-aminophenyl α-D-glucopyranoside showed similar membrane- damaging activities noted with Man-BSA. The results of hemolysis and MTT assay indicated that Man-BSA induced cell death and lysis of cholesterol-depleted cells. Co-treatment of Man-BSA and liposome-encapsulated As2O3 further increased the cytotoxicity of As2O3, resulting from improving As2O3 delivery efficiency into cancer cells. Collectively, our data indicate that Man-BSA displays novel membrane-damaging activities, and that cholesterol crucially regulates the mode of Man-BSA on damaging phospholipid bilayers. |
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