A direct ELISA assay for quantitative determination of the inhibitory potency of
small molecules inhibitors for JNK3
The c-jun N-terminal kinase 3 (JNK3) is a promising drug target for the treatment of neurological disorders.
Here we report a direct ELISA including the optimization of a nonradioactive immunosorbent JNK3 activity
assay to determine inhibitory potency of small-molecule inhibitors. Based on our previous JNK3 assay
and our recently optimized p38 mitogen activated protein kinase (MAPK) protocol for monitoring the
phosphorylation of activating-transcription factor 2 (ATF-2), we present a rapid and straightforward
alternative to conventional radioactive and indirect ELISA kinase assays. To validate the assay with the
optimized assay conditions we used reference compounds and achieved well comparable IC50 results to
published data. The use of a linked monoclonal antibody increased the specificity and the sensitivity of
the assay, reducing the required antibody concentration by approximately 100-fold. The novel protocol is
an accurate, easy-to-handle and robust screening assay for JNK3 and the assay performance was reduced
from 7.5 to 3 h.