这项研究报告了使用配备有微观扫描功能的量子级联激光VCD系统(称为多维VCD[MultiD-VCD])对四个不同昆虫翅膀上的振动圆二色性(VCD)的微观测量。机翼样本,包括(i)甲虫,Albopilosa(女),(ii)欧洲大黄蜂,VerspacrabroflavofasciataCameron,1903年(女),(iii)微小的蜻蜓,NannopphiapygmaeRambur,1842(男性),和(iv)蜻蜓,奥古马SymetrumgracileOguma,1915年(男性),在这项研究中使用。以100μm的空间分辨率获得VCD信号的二维图案(〜10mm×10mm)。测量涵盖了1500-1740cm-1范围内酰胺I和II的吸收峰。测量基于肽基团的立构规整连接的VCD信号的增强。模式明显依赖于物种。在样本(i)和(ii)中,机翼包含不同二级结构的蛋白质聚集体的分离结构域。每个微域的尺寸约为100μm。相比之下,在样品(iii)和(iv)中未检测到清晰的VCD光谱。一个可能的原因是立体规则多肽的链太短而不能在样品(iii)和(iv)中实现VCD增强。值得注意的是,由于物种之间的红外光谱几乎相同,因此仅在VCD光谱中观察到独特的特征。VCD结果暗示了蛋白质微观结构与每个物种的机翼拍打机制的联系。
This study reports the microscopic measurements of vibrational circular dichroism (VCD) on four different insect wings using a quantum cascade laser VCD system equipped with microscopic scanning capabilities (named multi-dimensional VCD [MultiD-VCD]). Wing samples, including (i) beetle, Anomala albopilosa (female), (ii) European hornet, Verspa crabro flavofasciata Cameron, 1903 (female), (iii) tiny dragonfly, Nannophya pygmae Rambur, 1842 (male), and (iv) dragonfly, Symetrum gracile Oguma, 1915 (male), were used in this study. Two-dimensional patterns of VCD signals (~10 mm × 10 mm) were obtained at a spatial resolution of 100 μm. Measurements covered the absorption peaks assigned to amides I and II in the range of 1500-1740 cm-1 . The measurements were based on the enhancement of VCD signals for the stereoregular linkage of peptide groups. The patterns were remarkably dependent on the species. In samples (i) and (ii), the wings comprised segregated domains of protein aggregates of different secondary structures. The size of each microdomain was approximately 100 μm. In contrast, no clear VCD spectra were detected in samples (iii) and (iv). One possible reason was that the chain of stereoregular polypeptides was too short to achieve VCD enhancement in samples (iii) and (iv). Notably, the unique features were only observed in the VCD spectra because the IR spectra were nearly the same among the species. The VCD results hinted at the connection of protein microscopic structures with the wing flapping mechanisms of each species.