Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Dalriada Drug Discovery, Mississauga, Ontario L5N 8G4, Canada.
Biochemistry. 2023 Nov 7;62(21):3085-3095. doi: 10.1021/acs.biochem.3c00337. Epub 2023 Oct 19.
Transglutaminases (TGases) are a family of calcium-dependent enzymes primarily known for their ability to cross-link proteins. Transglutaminase 2 (TG2) is one isozyme in this family whose role is multifaceted. TG2 can act not only as a typical transamidase through its catalytic core but also as a G-protein via its GTP binding site. These two discrete activities are tightly regulated by both environmental stimuli and redox reactions. Ubiquitously expressed in humans, TG2 has been implicated in numerous disease pathologies that require extensive investigation. The catalytic activity of TG2 can be monitored through various mechanisms, including hydrolysis, transamidation, or cleavage of isopeptide bonds. Activity assays are required to monitor the activity of this isozyme not only for studying its transamidation reaction but also for validation of therapeutics designed to abolish this activity. Herein, we present the design, synthesis, and evaluation of a new TG2 activity substrate based on a previously optimized inhibitor scaffold. The substrate exhibits excellent affinity, selectivity, and reactivity with TG2 ( = 3.0 μM). Furthermore, its application also allowed the discovery of unique hysteresis at play within the catalytic activity and inhibition reactivity of TG2.
转谷氨酰胺酶（TGases）是一组依赖于钙的酶，主要因其能够交联蛋白质的能力而闻名。该家族中的转谷氨酰胺酶 2（TG2）是一种同工酶，其作用具有多方面性。TG2 不仅可以通过其催化核心作为典型的转酰胺酶发挥作用，还可以通过其 GTP 结合位点作为 G 蛋白发挥作用。这两种不同的活性都受到环境刺激和氧化还原反应的严格调节。TG2 在人类中广泛表达，与许多需要广泛研究的疾病病理有关。可以通过多种机制监测 TG2 的催化活性，包括水解、转酰胺或异肽键的切割。需要进行活性测定来监测该同工酶的活性，不仅是为了研究其转酰胺反应，也是为了验证旨在消除该活性的治疗药物的有效性。在此，我们提出了一种基于先前优化的抑制剂支架的新型 TG2 活性底物的设计、合成和评价。该底物 对 TG2 具有优异的亲和力、选择性和反应性（ = 3.0 μM）。此外，其应用还发现了在 TG2 的催化活性和抑制反应性中起作用的独特滞后现象。
