Circadian rhythmic plant leaf-movement, called nyctinasty, is controlled by a time-course change in the internal concentration of the leaf movement factors (leaf-opening and leaf-closing substances) in the plant body. We revealed that the target cell for the leaf-movement factors is plant motor cell by using novel synthetic fluorescence labeled probes. Using photoaffinity probes 21, the specific binding proteins for potassium lespedezate 1, the leaf-opening substance of Cassia mimosoides L, are detected from the plasma membrane fraction of the plant motor cell. Our study is a rare successful result of the detection of membrane receptors by using a synthetic photoaffinity probe designed on a biologicallly active natural product. These results also advance a guideline for probe design towards successful photoaffinity labeling. The balance of concentration of the leaf movement factors is inversed during the day. The glycoside type leaf movement factor is hydrolyzed with β-glucosidase, the activity of which is regulated by the biological clock. The circadian rhythm observed in the leaf movement is introduced by activation of the β-glucosidase regulated by the biological clock. We synthesized the glyconoamidine gel 43 designed on potassium lespedezate, a glycoside type leaf-opening substance, and succeeded in purification of the β-glucosidase, a key enzyme of circadian rhythmic plant leaf-movement, by affinity chromatography using affinity gel 43.
