The conformational landscapes of β-ionone and two mutants (α-ionone and β-damascone) have been analyzed by means of state-of-the-art rotational spectroscopy and quantum-chemical calculations. The experiments performed at high resolution and sensitivity have provided a deep insight into their conformational spaces, assigning more than 8000 transitions corresponding to the rotational structures of 54 different species (3 isomers, 14 conformers, and 40 isotopologues). Methyl internal rotation dynamics were also observed and analyzed. The work proved the great flexibility of β-ionone due to its flatter potential energy surface. This feature confers on β-ionone a wider ability to interconvert between conformers with rather similar energies with respect to its mutants, allowing the retinal ligand to better adapt inside the binding pocket.

中文翻译：

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气相色谱中高分辨光谱法证明β-紫罗兰酮及其两个突变体的形状，动力学和稳定性

β-紫罗兰酮和两个突变体（α-紫罗兰酮和β-大马cone）的构象态势已通过最新的旋转光谱法和量子化学计算方法进行了分析。以高分辨率和高灵敏度进行的实验对它们的构象空间提供了深刻的见解，分配了8000多个跃迁，这些跃迁对应于54个不同物种（3个异构体，14个构象异构体和40个同位素异体）的旋转结构。还观察并分析了甲基内旋转动力学。这项工作证明了β-紫罗兰酮具有更平坦的势能表面，因此具有很大的柔韧性。该特征赋予β-紫罗兰酮更大的能力，使其与其突变体具有相当相似能量的构象异构体之间相互转化，从而使视网膜配体更好地适应结合袋内部。