toxicity of the base molecule examples of such moieties are described in a variety of texts such as remington 39 s pharmaceutical sciences the term u201c kinase u201d as used herein refers to members of the histidine kinase protein family or superfamily sources of kinase for use in the invention can be purified protein derived from natural or recombinant sources with purified recombinant protein being generally preferred histidine kinase substrates are either the histidine kinase itself via an autophosphorylation mechanism or a specific cognate response regulator protein via a transphosphorylation mechanism the term u201c cognate response regulator u201d protein as used herein refers to non kinase members of two component systems cognate response regulator proteins suitable for use in the invention can include purified protein derived from natural or recombinant sources with purified recombinant protein being generally preferred the cognate response regulator could also be a fusion protein or peptide that contains a recognition domain for the corresponding hisitidine kinase the term u201c high throughput u201d as used herein refers to an assay design that allows easy analysis of multiple samples simultaneously capacity for robotic manipulation and use of small sample volume examples of assay formats include 96 well or 384 well plates used for liquid handling experiments it is well known by those in the art that as miniaturization of plastic molds and liquid handling devices are advanced or as improved assay devices are designed that greater numbers of samples may.