Structure-activity relationship, kinetic mechanism, and selectivity for a new class of ubiquitin C-terminal hydrolase-L1 (UCH-L1) inhibitors

Bioorg Med Chem Lett. 2007 Jul 1;17(13):3729-32. doi: 10.1016/j.bmcl.2007.04.027. Epub 2007 Apr 10.


3-Amino-2-keto-7H-thieno[2,3-b]pyridin-6-one derivatives were discovered as moderately potent inhibitors of ubiquitin C-terminal hydrolase-L1 (UCH-L1) utilizing an assay that measures hydrolysis of the fluorogenic substrate Ub-AMC. SAR studies revealed that both the carboxylate at the 5-position and the 6-pyridone ring were critical for inhibitory activity. Furthermore, activity was dependent on the nature of the ketone substituent at the 2-position, with 4-Me-Ph and 2-naphthyl being best. Kinetic mechanism studies revealed that these compounds were uncompetitive inhibitors of UCH-L1, binding only to the Michaelis-complex and not to free enzyme. The active compounds were selective for UCH-L1, exhibiting neither inhibition of other cysteine hydrolases (e.g., UCH-L3, papain, isopeptidase T, caspase-3, and tissue transglutaminase) nor cytotoxicity in N2A cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Chemistry, Pharmaceutical / methods*
  • Cysteine / chemistry
  • Drug Design
  • Enzyme Inhibitors / chemical synthesis*
  • Enzyme Inhibitors / chemistry
  • Humans
  • Ketones / chemistry
  • Kinetics
  • Models, Chemical
  • Protein Binding
  • Structure-Activity Relationship
  • Substrate Specificity
  • Ubiquitin Thiolesterase / antagonists & inhibitors*
  • Ubiquitin Thiolesterase / chemistry


  • Enzyme Inhibitors
  • Ketones
  • UCHL1 protein, human
  • Ubiquitin Thiolesterase
  • Cysteine