Binding of ethylene analogs and cyclic olefins to a Triton X-100 extract from plants: Comparison with in vivo activities

Abstract

The binding constants of various olefins were determined with a Triton X-100 extract of mung bean sprouts. The olefins tested included compounds that have been reported to induce an ethylene response in vivo as well as olefins reported to block the ethylene response. Both types of compounds were bound by the Triton X-100 extract, and the binding constants in vitro were usually considerably lower than those obtained in in vivo studies as measured by gas phase concentrations. Increased solubility due to Triton X-100 solution appears to be partly responsible. The in vitro binding order of compounds reported to induce an ethylene response was similar to their order of in vivo activity. Also, the compounds which gave an anti-ethylene response in vivo bound to the extract in approximately the same order as their in vivo effectiveness. These results suggest that binding of olefins is not the only factor necessary for an ethylene response. Although binding is necessary for activity, another factor must be involved after binding, and this may be π-acceptance.