Detection of nitroxyl (HNO), the transient one-electron reduced form of nitric oxide, is a significant challenge owing to its high reactivity with biological thiols (rate constants as high as 109M−1 s−1). Reported herein is a new thiol-based HNO-responsive trigger that can compete against reactive thiols for HNO. This process forms an N-hydroxysulfenamide intermediate which cyclizes to release a masked fluorophore leading to fluorescence enhancement. To ensure a rapid cyclization step, the disclosed design capitalizes on two established physical organic phenomena: the alpha-effect and the Thorpe-Ingold effect. Using this new trigger, NitroxylFluor was developed; a selective HNO-responsive fluorescent probe. Treatment of NitroxylFluor with an HNO donor results in a 16-fold turn-on. This probe also exhibits excellent selectivity over various reactive nitrogen, oxygen, and sulfur species and efficacy in the presence of thiols (e.g., glutathione in mM concentrations). Also, live cell imaging of HNO using NitroxylFluor was performed.
一氧化氮(HNO)是
一氧化氮的瞬时单电子还原形式,由于它与
生物硫醇的高反应性(速率常数高达 109M-1 s-1),因此检测它是一项重大挑战。本文报告的是一种基于
硫醇的新型 HNO 反应触发器,它可以与活性
硫醇竞争 HNO。这一过程会形成一个 N-羟基亚磺酰胺中间体,该中间体环化后会释放出被掩蔽的荧光团,从而导致荧光增强。为确保快速环化步骤,所披露的设计利用了两个已确立的物理有机现象:α 效应和索普-英戈德效应。利用这种新的触发器,开发出了 NitroxylFluor;一种选择性 HNO 反应荧光探针。用 HNO 给体处理 NitroxylFluor 可使其开启 16 倍。这种探针还对各种活性氮、氧和
硫物种具有极佳的选择性,在存在
硫醇(如 mM 浓度的
谷胱甘肽)的情况下也有效。此外,还利用 NitroxylFluor 对 HNO 进行了活细胞成像。