title: Hormone-binding studies and the misuse of precipitation assays.
abstract: Many methods are available for determining binding of small-molecular ligands to macromolecules. In studies on plant hormone binding, precipitation of putative hormone-protein complexes with ammonium sulphate is often used as the sole method of assay. Several such reports on auxin binding have been re-examined, using additional assay procedures. The results show that apparent binding activity measured by ammonium sulphate precipitation may be undetectable by independent, less ambiguous methods. It is concluded that hormone-binding studies that rely solely on the precipitation assay can be grossly misleading, and that this assay, if used at all, should always be validated against a procedure less likely to generate artefacts. An example of such validation for a plant protein is shown.
authors.affiliation: Sittingbourne Research Centre, Shell Research Limited, ME9 8AG, Sittingbourne, Kent, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Venis