Vidal Benedicto de Campos
Department of Structural and Functional Biology, Institute of Biology, University of Campinas (Unicamp), Rua Monteiro Lobato 255, CEP 013083-862 Campinas, SP, Brazil.
Acta Histochem. 2014 Oct;116(8):1359-66. doi: 10.1016/j.acthis.2014.08.007. Epub 2014 Sep 8.
Histological and histochemical observations support the hypothesis that collagen fibers can link to elastic fibers. However, the resulting organization of elastin and collagen type complexes and differences between these materials in terms of macromolecular orientation and frequencies of their chemical vibrational groups have not yet been solved. This study aimed to investigate the macromolecular organization of pure elastin, collagen type I and elastin-collagen complexes using polarized light DIC-microscopy. Additionally, differences and similarities between pure elastin and collagen bundles (CB) were investigated by Fourier transform-infrared (FT-IR) microspectroscopy. Although elastin exhibited a faint birefringence, the elastin-collagen complex aggregates formed in solution exhibited a deep birefringence and formation of an ordered-supramolecular complex typical of collagen chiral structure. The FT-IR study revealed elastin and CB peptide NH groups involved in different types of H-bonding. More energy is absorbed in the vibrational transitions corresponding to CH, CH2 and CH3 groups (probably associated with the hydrophobicity demonstrated by 8-anilino-1-naphtalene sulfonic acid sodium salt [ANS] fluorescence), and to νCN, δNH and ωCH2 groups of elastin compared to CB. It is assumed that the α-helix contribution to the pure elastin amide I profile is 46.8%, whereas that of the B-sheet is 20% and that unordered structures contribute to the remaining percentage. An FT-IR profile library reveals that the elastin signature within the 1360-1189cm(-1) spectral range resembles that of Conex-Toray aramid fibers.
组织学和组织化学观察结果支持胶原纤维可与弹性纤维相连的假说。然而，弹性蛋白和I型胶原复合物的最终组织形式以及这些材料在大分子取向及其化学振动基团频率方面的差异尚未得到解决。本研究旨在使用偏振光微分干涉对比显微镜研究纯弹性蛋白、I型胶原和弹性蛋白-胶原复合物的大分子组织。此外，通过傅里叶变换红外（FT-IR）显微光谱研究了纯弹性蛋白和胶原束（CB）之间的异同。尽管弹性蛋白表现出微弱的双折射，但在溶液中形成的弹性蛋白-胶原复合聚集体表现出强烈的双折射，并形成了典型的胶原手性结构的有序超分子复合物。FT-IR研究表明，弹性蛋白和CB肽的NH基团参与了不同类型的氢键形成。与CB相比，在对应于CH、CH2和CH3基团（可能与8-苯胺基-1-萘磺酸钠盐[ANS]荧光显示的疏水性有关）以及弹性蛋白的νCN、δNH和ωCH2基团的振动跃迁中吸收了更多能量。据推测，α-螺旋对纯弹性蛋白酰胺I谱的贡献为46.8%，β-折叠的贡献为20%，无序结构贡献其余百分比。一个FT-IR谱库显示，在1360-1189cm(-1)光谱范围内，弹性蛋白的特征与帝人芳纶纤维的特征相似。
