Fingerprinting Desmosine-Containing Elastin Peptides
Fingerprinting Desmosine-Containing Elastin Peptides
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DOI：
10.1007/s13361-014-1075-9
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发表时间：
2015-05-01
影响因子：
3.2
通讯作者：
Schmelzer, Christian E. H.
中科院分区：
文献类型：
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作者：
Schraeder, Christoph U.;Heinz, Andrea;Schmelzer, Christian E. H.
弹性蛋白是颌类脊椎动物细胞外基质的重要蛋白质，为许多组织提供弹性。它以其可溶性前体原弹性蛋白的形式分泌，其随后在弹性纤维组装过程中交联。该过程涉及两种四功能氨基酸锁链素（DES）和异锁链素（IDES）的形成，这是弹性蛋白所特有的。由此产生的高度交联赋予蛋白质显著的性质，包括机械完整性、不溶性和长期稳定性。这些特征阻碍了成熟弹性蛋白的结构解析。然而，通过蛋白水解释放的线性和交联肽的MS 2数据可以提供对弹性蛋白结构的间接见解。在这项研究中，我们进行了能量分辨碰撞诱导解离实验DES，IDES，其衍生物，DES/IDES-含有肽，以确定特征产物离子。结果发现，所有研究的化合物产生相同的产物离子簇在升高的碰撞能量。使用这些离子的精确质量的元素组成测定揭示了CxHyN型的分子式，这表明DES/IDES的吡啶核心即使在相对高的碰撞能量下也保持完整。这些特定产物离子的发现使得能够开发基于相似性的评分算法，该算法成功应用于牛弹性蛋白酶的LC-MS/MS数据，用于鉴定DES-/IDES-交联肽。这种方法有利于直接调查的天然交联弹性蛋白。
Elastin is a vital protein of the extracellular matrix of jawed vertebrates and provides elasticity to numerous tissues. It is secreted in the form of its soluble precursor tropoelastin, which is subsequently cross-linked in the course of the elastic fiber assembly. The process involves the formation of the two tetrafunctional amino acids desmosine (DES) and isodesmosine (IDES), which are unique to elastin. The resulting high degree of cross-linking confers remarkable properties, including mechanical integrity, insolubility, and long-term stability to the protein. These characteristics hinder the structural elucidation of mature elastin. However, MS2 data of linear and cross-linked peptides released by proteolysis can provide indirect insights into the structure of elastin. In this study, we performed energy-resolved collision-induced dissociation experiments of DES, IDES, their derivatives, and DES-/IDES-containing peptides to determine characteristic product ions. It was found that all investigated compounds yielded the same product ion clusters at elevated collision energies. Elemental composition determination using the exact masses of these ions revealed molecular formulas of the type CxHyN, suggesting that the pyridinium core of DES/IDES remains intact even at relatively high collision energies. The finding of these specific product ions enabled the development of a similarity-based scoring algorithm that was successfully applied on LC-MS/MS data of bovine elastin digests for the identification of DES-/IDES-cross-linked peptides. This approach facilitates the straightforward investigation of native cross-links in elastin.