Identification and characterization of 3-substituted pyrazolyl esters as alternate substrates for cathepsin B: the confounding effects of DTT and cysteine in biological assays.
Substituted pyrazole esters were identified as hits in a high throughput screen (HTS) of the NIH Molecular Libraries Small Molecule Repository (MLSMR) to identify inhibitors of the enzyme cathepsin B. Members of this class, along with functional group analogs, were synthesized in an effort to define the structural requirements for activity. Analog characterization was hampered by the need to include a reducing agent such as dithiothreitol (DTT) or cysteine in the assay, highlighting the caution required in interpreting biological data gathered in the presence of such nucleophiles. Despite the confounding effects of DTT and cysteine, our studies demonstrate that the pyrazole 1 acts as alternate substrate for cathepsin B, rather than as an inhibitor.
Myers
Michael C
MC
Penn Center for Molecular Discovery, University of Pennsylvania, 1024 Vagelos Research Laboratories, Philadelphia, PA 19104-6383, USA.
Napper
Andrew D
AD
Motlekar
Nuzhat
N
Shah
Parag P
PP
Chiu
Chun-Hao
CH
Beavers
Mary Pat
MP
Diamond
Scott L
SL
Huryn
Donna M
DM
Smith
Amos B
AB
D001681:Biological Assay / Q000379:methods; D002244:Carbon / Q000737:chemistry; D002401:Cathepsin B / Q000737:chemistry* / Q000378:metabolism; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003545:Cysteine / Q000494:pharmacology*; D004229:Dithiothreitol / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D004952:Esters / Q000737:chemistry*; D006801:Humans; D020128:Inhibitory Concentration 50; D008956:Models, Chemical; D011485:Protein Binding; D019163:Reducing Agents / Q000494:pharmacology; D013997:Time Factors
D004952:Esters; D019163:Reducing Agents; D002244:Carbon; D002401:Cathepsin B; D003545:Cysteine; D004229:Dithiothreitol