Factor XIIIa (FXIIIa) is a transglutaminase of major therapeutic interest for the development of anticoagulants due to its essential role in the blood coagulation cascade. While numerous FXIIIa inhibitors have been reported, they failed to reach clinical evaluation due to their lack of metabolic stability and low selectivity over transglutaminase 2 (TG2). Furthermore, the chemical tools available for the study of FXIIIa activity and localization are extremely limited. To combat these shortcomings, we designed, synthesised, and evaluated a library of 21 novel FXIIIa inhibitors. Electrophilic warheads, linker lengths, and hydrophobic units were varied on small molecule and peptidic scaffolds to optimize isozyme selectivity and potency. A previously reported FXIIIa inhibitor was then adapted for the design of a probe bearing a rhodamine B moiety, producing the innovative KM93 as the first known fluorescent probe designed to selectively label active FXIIIa with high efficiency (kinact/KI = 127,300 M−1 min−1) and 6.5-fold selectivity over TG2. The probe KM93 facilitated fluorescent microscopy studies within bone marrow macrophages, labelling FXIIIa with high efficiency and selectivity in cell culture. The structure–activity trends with these novel inhibitors and probes will help in the future study of the activity, inhibition, and localization of FXIIIa.
因子 XIIIa(FXIIIa)是一种转谷氨酰胺酶,在血液凝固级联过程中起着至关重要的作用,因此对抗凝剂的开发具有重要的治疗意义。虽然已有许多 FXIIIa 抑制剂的报道,但由于它们缺乏代谢稳定性,而且对转谷氨酰胺酶 2 (TG2) 的选择性较低,因此未能进行临床评估。此外,用于研究 FXIIIa 活性和定位的化学工具也极为有限。为了克服这些不足,我们设计、合成并评估了一个包含 21 种新型 FXIIIa 抑制剂的文库。我们改变了小分子和多肽支架上的亲电弹头、链接长度和疏水单元,以优化同工酶的选择性和效力。随后,对之前报道的一种 FXIIIa 抑制剂进行了改良,设计出了一种带有罗丹明 B 分子的探针,从而产生了创新性的 KM93,它是第一个已知的荧光探针,可选择性地标记活性 FXIIIa,具有高效率(kinact/KI = 127,300 M-1 min-1)和比 TG2 高 6.5 倍的选择性。KM93 探针有助于在骨髓巨噬细胞内进行荧光显微镜研究,在细胞培养中高效、选择性地标记 FXIIIa。这些新型抑制剂和探针的结构-活性趋势将有助于今后研究 FXIIIa 的活性、抑制和定位。