Hong B S, Yang M C, Liang J N, Pang P K
Peptides. 1986 Nov-Dec;7(6):1131-5. doi: 10.1016/0196-9781(86)90143-9.
The analysis of the spectrum of circular dichroism (CD) of methionine-oxidized bovine parathyroid hormone peptide, bPTH(1-34) revealed that approximately 43% of the orderly conformation (alpha-helix and beta-sheet) was converted into random coil structure. This peptide failed to elicit any hypotensive response in rats at any of the tested doses from 0.01 to 0.05 mg/ml. The blue shift of tryptophan fluorescence and the increase in the fluorescence intensity of the fluorescence probe 2-p-toluidinylnaphthalene-6-sulfonate (TNS) bound to the oxidized peptide indicated that the more hydrophobic environment was generated in the tryptophan domain as well as the molecule as a whole when the methionines in the peptide were oxidized. Modification of arginine with 1,2-cyclohexanedione (CHD) reduced 30% to 50% of the hypotensive action of the peptide hormone. Similar results in the increase of hydrophobicity of the arginine-modified peptide were also observed. These studies suggest that the conformational changes due to the methionine oxidation or arginine modification may be related to the inactivation of the vascular activity of bPTH(1-34).
对甲硫氨酸氧化的牛甲状旁腺激素肽bPTH(1 - 34)的圆二色光谱（CD）分析表明，约43%的有序构象（α-螺旋和β-折叠）转变为无规卷曲结构。在0.01至0.05 mg/ml的任何测试剂量下，该肽在大鼠中均未引发任何降压反应。与氧化肽结合的色氨酸荧光蓝移以及荧光探针2 - 对甲苯胺基萘-6-磺酸盐（TNS）荧光强度增加表明，当肽中的甲硫氨酸被氧化时，色氨酸结构域以及整个分子中产生了更疏水的环境。用1,2 - 环己二酮（CHD）修饰精氨酸使肽激素的降压作用降低了30%至50%。在精氨酸修饰肽的疏水性增加方面也观察到了类似结果。这些研究表明，由甲硫氨酸氧化或精氨酸修饰引起的构象变化可能与bPTH(1 - 34)血管活性的失活有关。
