Whereas l-3-oxo-hexanoyl homoserine lactone (OHHL) is the active enantiomer of the of LuxR-regulated quorum sensing (QS) autoinducer, its d isomer is implicitly considered as inactive. The present work aims to clarify this l-specificity and investigate whether it extends to some analogues in the acyl homoserine lactone (AHL) family. For this purpose, OHHL and a series of AHL analogs were synthesized in racemic and enantiomerically pure d and l forms and their ability to induce or attenuate bioluminescence in the LuxR-dependent QS system was evaluated. In this study, l-isomers are confirmed as either the only, or as the most active, enantiomers. However, in several cases, especially for the natural ligand of LuxR (OHHL) and the very similar AHL agonist analogue 2, the d-isomer cannot be considered as totally inactive on QS. Molecular modelling suggests that when the lactone moiety of the d-isomer is able to twist, enabling the lactone carbonyl group and the amide function to interact with the key residues in the binding site, then the d-isomer can exhibit some activity.

而升-3-氧代-己酰基高丝氨酸内酯（OHHL）是的蛋白LuxR调节的群体感应（QS）自体诱导物，其的活性对映体d异构体被隐式地被视为无效。本工作旨在阐明这种l-特异性，并研究它是否扩展至酰基高丝氨酸内酯（AHL）家族中的某些类似物。为此，合成了外消旋和对映体纯的d和l形式的OHHL和一系列AHL类似物，并评估了它们在LuxR依赖的QS系统中诱导或减弱生物发光的能力。在这项研究中，1-异构体被确认为是唯一的或最具活性的对映异构体。但是，在某些情况下，尤其是对于LuxR（OHHL）的天然配体和非常相似的AHL激动剂类似物2，不能认为d-异构体对QS完全无活性。分子模型表明，当d-异构体的内酯部分能够扭曲，使内酯羰基和酰胺功能与结合位点中的关键残基相互作用时，d-异构体就可以表现出一定的活性。