Sung Yu-Sheng, Khvalbota Liudmyla, Dhaubhadel Umang, Špánik Ivan, Armstrong Daniel W
Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas, USA.
Institute of Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Bratislava, Slovakia.
Chirality. 2023 Aug;35(8):461-468. doi: 10.1002/chir.23543. Epub 2023 Mar 16.
D-amino acids and epimeric peptides/proteins can play crucial biological roles and adversely affect protein folding and oligopeptide aggregation in age-related pathologies in humans. This has ignited interest in free D-amino acids as well as those incorporated in peptides/proteins and their effects in humans. However, such stereoisomeric analytes are often elusive and in low abundance with few existing methodologies capable of scouting for and identifying them. In this work, we examine the feasibility of using teicoplanin aglycone, a macrocyclic antibiotic, which has been reported to strongly retain D-amino acids and peptides with a D-amino acid on the C-terminus, for use as a solid phase extraction (SPE) medium. The HPLC retention factors of L-/D-amino acids and C-terminus modified D-amino acid-containing peptides and their L-amino acid exclusive counterparts on teicoplanin aglycone are presented. Retention curve differences between amino acids and peptides highlight regions of solvent composition that can be utilized for their separation. This approach is particularly useful when coupled with enzymatic hydrolysis via carboxypeptidase Y to eliminate all L-amino acid exclusive peptides. The remaining peptides with carboxy-terminal D-amino acids are then more easily concentrated and identified.
D-氨基酸以及差向异构肽/蛋白质在人类与年龄相关的病理过程中可发挥关键的生物学作用，并对蛋白质折叠和寡肽聚集产生不利影响。这引发了人们对游离D-氨基酸以及那些掺入肽/蛋白质中的D-氨基酸及其对人类影响的兴趣。然而，这类立体异构分析物往往难以捉摸且丰度较低，现有的能够搜寻和鉴定它们的方法很少。在这项工作中，我们研究了使用替考拉宁苷元（一种大环抗生素）作为固相萃取（SPE）介质的可行性，据报道，该抗生素能强烈保留D-氨基酸以及C端带有D-氨基酸的肽。文中给出了L-/D-氨基酸以及C端修饰的含D-氨基酸肽及其仅含L-氨基酸的对应物在替考拉宁苷元上的HPLC保留因子。氨基酸和肽之间的保留曲线差异突出了可用于它们分离的溶剂组成区域。当与羧肽酶Y进行酶促水解相结合以消除所有仅含L-氨基酸的肽时，这种方法特别有用。然后，剩余的具有羧基末端D-氨基酸的肽更容易被浓缩和鉴定。
