Most leguminous plants close their leaves in the evening, and open them early in the morning according to the circadian rhythm controlled by a biological clock. These movements involve two bioactive substances, leaf-opening and closing substance. To investigate the mechanism of nyctinasty on molecular level, we synthesized two bioactive probes: one is a fluorescence labeled probe for identifying the target cell of leaf-movement substance; the other is a photoaffinity probe for identification of receptor protein of bioactive substances. And we carried out bioorganic studies of nyctinasty  using these probes.