Ragnoni Elena, Palombo Francesca, Green Ellen, Winlove C Peter, Di Donato Mariangela, Lapini Andrea
LENS, European Laboratory for Nonlinear Spectroscopies, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Florence, Italy and Department of Physics, University of Siegen, Walter-Flex Str. 3, D-57068 Siegen, Germany.
School of Physics and Astronomy, University of Exeter, Exeter EX4 4QJ, UK.
Phys Chem Chem Phys. 2016 Oct 12;18(40):27981-27990. doi: 10.1039/c6cp04049g.
Elastin is the main protein to confer elasticity to biological tissues, through the formation of a hierarchical network of fibres. α-Elastin, a soluble form of the protein, is widely used in studies of the biosynthesis of human elastic tissue and exhibits coacervation in solution. This process involves the association of α-elastin molecules through a liquid-liquid phase transition, which is reversible unless the temperature is driven sufficiently high to induce the formation of insoluble aggregates. The thermodynamics of this process have attracted interest over many years and in the present work we used ultrafast nonlinear infrared spectroscopy of the amide I protein backbone vibration to resolve the secondary structural changes occurring during coacervation and probe the protein dynamics on a picosecond time scale. Four classes of carbonyl oscillators with distinct absorption peaks were revealed and, through narrowband excitation, vibrational and anisotropy decays could be distinguished. Analysis of the vibrational lifetimes and anisotropy decay times of these bands characterized the conformational changes and revealed the structural bases of the coacervation process.
弹性蛋白是赋予生物组织弹性的主要蛋白质，它通过形成分级纤维网络来实现这一功能。α-弹性蛋白是该蛋白质的一种可溶形式，广泛应用于人类弹性组织生物合成的研究，并在溶液中表现出凝聚作用。这个过程涉及α-弹性蛋白分子通过液-液相转变进行缔合，这种转变是可逆的，除非温度升高到足以诱导形成不溶性聚集体。多年来，这个过程的热力学一直备受关注。在本研究中，我们利用酰胺I蛋白主链振动的超快非线性红外光谱来解析凝聚过程中发生的二级结构变化，并在皮秒时间尺度上探测蛋白质动力学。研究揭示了具有不同吸收峰的四类羰基振荡器，通过窄带激发，可以区分振动和各向异性衰减。对这些谱带的振动寿命和各向异性衰减时间的分析表征了构象变化，并揭示了凝聚过程的结构基础。
