Background:

IC50: 53 nM

Cathepsin G (EC 3.4.21.20, chymotrypsin-like proteinase, neutral proteinase) is an enzymatic protein belonging to the peptidase or protease families. In humans, it is coded by the CTSG gene. Cathepsin G Inhibitor I is a potent, selective, reversible, competitive, non-peptide inhibitor of cathepsin G.

In vitro: Cathepsin G Inhibitor I shows reversible, competitive inhibition with IC50 and Ki values of 53 ± 12 (N = 10) and 63 ± 14 nM (N = 5), respectively. Another attribute of Cathepsin G Inhibitor I relates to its selectivity vs other serine proteases. It weakly inhibits chymotrypsin (Ki = 1.5 ± 0.2 μM), and poorly inhibits (<50% inhibition at 100 μM) thrombin, factor Xa, factor IXa, plasmin, trypsin, tryptase, proteinase 3, and human leukocyte elastase [1].

In vivo: Cathepsin G Inhibitor I is currently in in-vitro investigation and no animal in vivo study is ongoing [1].

Clinical trial: Cathepsin G Inhibitor I is currently in the preclinical development and no clinical trial is ongoing.

Reference:
[1] Greco MN, Hawkins MJ, Powell ET, Almond HR Jr, Corcoran TW, de Garavilla L, Kauffman JA, Recacha R, Chattopadhyay D, Andrade-Gordon P, Maryanoff BE.  Nonpeptide inhibitors of cathepsin G: optimization of a novel beta-ketophosphonic acid lead by structure-based drug design. J Am Chem Soc. 2002;124(15):3810-1.