Radioligand binding assay

[gorkin]

Hi,

Im new here! Having some problems with a radioligand binding assay, namely im wondering whether or not to use a competitive scheme to determine the Kd for a compound from my enzyme. I have relatively little radiolabeled ligand, so I have to use it rather conservatively. So why not use a constant concentration and then add specific amounts of unlabeled ligand? Im not sure if this is acceptable though...Anyone have any suggestions?

thanks.