I am developing a biochemical assay for IKK-alpha and IKK beta. I got the proteins (active kinases) from Signal Chem. What I see is ADP production with ATP+IKKtide (my acceptor substrate) and exactly the same response with just ATP alone (even in the absence of IKKtide). I contacted Signal Chem and they ran ADP Glo and also see the same response I see. I have known kinases to show some non-productive hydrolysis in the absence of acceptor substrate but nothing like what I am seeing currently with these enzymes, (superimposed graphs with my controls). Has anyone seen a response like this? Could it be due to autophosphorylation? This is the substrate recommended in several papers....Any help will be appreciated.