Investigation of cis/trans proline isomerism in a multiply occurring peptide fragment from human salivary proline-rich glycoprotein.
Investigation of cis/trans proline isomerism in a multiply occurring peptide fragment from human salivary proline-rich glycoprotein.
复制标题
研究人唾液富含脯氨酸的糖蛋白中多次出现的肽片段中的顺式/反式脯氨酸异构体。
DOI：
10.1111/j.1399-3011.1991.tb01523.x
复制
发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Loomis,PM
中科院分区：
文献类型：
--
作者：
Loomis,RE;Gonzalez,M;Loomis,PM
利用13 C核磁共振（NMR）和圆二色性（CD）光谱研究了人唾液富含脯氨酸糖蛋白（PRG）中8个含脯氨酸肽段在2 ×蒸馏水（经金属离子螯合树脂处理）中的溶液构象。肽序列和首字母缩写如下：PRG9 - 2 = NH2-G（I）-P（2）-CONH2，PRG9 - 3 = NH2-G（1）-P（2）-P（3）-CONH2，PRG9 - 4 = NH2-G（1）-P（2）-P（3）-P（4）-CONH2，PRG9 - 5 = NH2-G（1）-P（2）-P（3）-P（4）-H（5）-CONH2，PRG9 - 6 = NH2-G（1）-P（2）-P（3）-P（4）-H（5）-P（6）-CONH2，PRG9 - 7 = NH2-G（1）-P（2）-P（3）-P（4）-H（5）-P（6）-G（7）-CONH2，PRG9 - 8 = NH2-G（1）-P（2）-P（3）-P（4）-H（5）-P（6）-G（7）-K（8）-CONH2和PRG9 - 9 = NH2-G（1）-P（2）-P（3）-P（4）-H（5）-P（6）-G（7）-K（8）-P（9）~（13）C-NMR谱的序列特异性共振归属表明，反式脯氨酸异构体主导肽段的构象。CD结果清楚地表明，PRG 9 - 3 → PRG 9 - 5中存在聚-L-脯氨酸II螺旋作为主要构象，PRG 9 - 6 → PRG 9 - 9中补充β-和/或γ-转角。这些数据表明，在“无金属”水中，天然PRG可能含有几个小的聚-l-脯氨酸II螺旋沿着β-和/或γ-转角。由于脯氨酸是天然PRG中存在的主要氨基酸，这些局部构象可能有助于PRG的全局构象，并作为决定其生物活性的主要力量。
The solution‐state conformations of eight proline‐containing peptide fragments found in human salivary proline‐rich glycoprotein (PRG) were investigated in 2 × distilled water (treated with metal ion chelating resin) using13C‐nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. The peptide sequences and acronyms were as follows: PRG9‐2 = NH2‐G(I)‐P(2)‐CONH2, PRG9‐3 = NH2‐G(1)‐P(2)‐P(3)‐CONH2,PRG9‐4 = NH2‐G(1)‐P(2)‐P(3)‐P(4)‐CONH2, PRG9‐5 = NH2‐G(1)‐P(2)‐P(3)‐P(4)‐H(5)‐CONH2,PRG9‐6 = NH2‐G(1)‐P(2)‐P(3)‐P(4)‐H(5)‐P(6)‐CONH2, PRG9‐7 = NH2‐G(1)‐P(2)‐P(3)‐P(4)‐H(5)‐P(6)‐G(7)‐CONH2, PRG9‐8 = NH2‐G(1)‐P(2)‐P(3)‐P(4)‐H(5)‐P(6)‐G(7)‐K(8)‐CONH2and PRG9‐9 = NH2‐G(1)‐P(2)‐P(3)‐P(4)‐H(5)‐P(6)‐G(7)‐K(8)‐P(9)‐CONH2.Sequence‐specific resonance assignments from the13C‐NMR spectra indicated that thetransproline isomer dominated the conformations of the peptides. CD results clearly showed the presence of the poly‐l‐proline II helix as the major conformation in PRG9‐3 → PRG9‐5, supplemented byβ‐ and/orγ‐turns in PRG9‐6 → PRG9‐9. These data suggest that in “metal free” water, native PRG could contain several small poly‐l‐proline II helices along withβ‐and/orγ‐turns. Since proline is the major amino acid present in native PRG, these localized conformations may contribute to PRG's global conformation and act as a primary force in determining its biological activities.