Tang Ching-Chia, Shi Yi-Jun, Chen Ying-Jung, Chang Long-Sen
Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
Int J Mol Sci. 2017 Feb 28;18(3):520. doi: 10.3390/ijms18030520.
The aim of the present study was to investigate whether glycated ovalbumin (OVA) showed novel activity at the lipid-water interface. Mannosylated OVA (Man-OVA) was prepared by modification of the carboxyl groups with -aminophenyl α-dextro (d)-mannopyranoside. An increase in the number of modified carboxyl groups increased the membrane-damaging activity of Man-OVA on cell membrane-mimicking vesicles, whereas OVA did not induce membrane permeability in the tested phospholipid vesicles. The glycation of carboxyl groups caused a notable change in the gross conformation of OVA. Moreover, owing to their spatial positions, the Trp residues in Man-OVA were more exposed, unlike those in OVA. Fluorescence quenching studies suggested that the Trp residues in Man-OVA were located on the interface binds with the lipid vesicles, and their microenvironment was abundant in positively charged residues. Although OVA and Man-OVA showed a similar binding affinity for lipid vesicles, the lipid-interacting feature of Man-OVA was distinct from that of OVA. Chemical modification studies revealed that Lys and Arg residues, but not Trp residues, played a crucial role in the membrane-damaging activity of Man-OVA. Taken together, our data suggest that glycation of carboxyl groups causes changes in the structural properties and membrane-interacting features of OVA, generating OVA with membrane-perturbing activities at the lipid-water interface.
本研究的目的是调查糖基化卵清蛋白（OVA）在脂质 - 水界面是否表现出新型活性。通过用α - 右旋（d）-甘露吡喃糖苷 - 氨基苯修饰羧基来制备甘露糖基化OVA（Man - OVA）。修饰羧基数量的增加会增强Man - OVA对模拟细胞膜囊泡的膜损伤活性，而OVA在测试的磷脂囊泡中不会诱导膜通透性。羧基的糖基化导致OVA的总体构象发生显著变化。此外，由于它们的空间位置，Man - OVA中的色氨酸残基比OVA中的更暴露。荧光猝灭研究表明，Man - OVA中的色氨酸残基位于与脂质囊泡结合的界面上，并且它们的微环境中富含带正电荷的残基。尽管OVA和Man - OVA对脂质囊泡表现出相似的结合亲和力，但Man - OVA与脂质相互作用的特征与OVA不同。化学修饰研究表明，赖氨酸和精氨酸残基而非色氨酸残基在Man - OVA的膜损伤活性中起关键作用。综上所述，我们的数据表明羧基的糖基化会导致OVA的结构性质和膜相互作用特征发生变化，从而产生在脂质 - 水界面具有膜扰动活性的OVA。
