Albizzia plants close their leaves in the evening, as if to sleep, and open them in the morning according to the circadian rhythum. Potassium β-D-glucopyranosyl-12-hydroxyjasmonate was isolated as leaf-closing factor (LCF) of Albizzia saman. We developed molecular probes consisting of modified LCF in order to identify its mode of action. However, it is often discussed whether molecular probes containing a larger and less polar functional unit such as fluorescence dye can bind to genuine binding protein of a natural product in living organisms. So, we need appropriate negative control. And an enantiomer of a biologically active natural product can be used as an ideal control because all physical propaties except for optical rotation and affinity to binding proteins are identical between a pair of enantiomers. Thus, enantio-differential approach that compares the results using a pair of probes that was prepared from a pair of enantiomers would be an ideal method in the bioorganic study using molecular probes. We synthesized probe 11 and biologically inactive enantiomer-type probe 12. And carried out fluorescence labeling study using 11 and 12. The results was clearly shown that the motor cells contain some specific binding protein that can differentiate the stereochemistry of the ligands. Similarly, we synthesized enantio pair-type photoaffinity-labeling probes 20 and 21, and used them for photoaffinity labeling of receptor for LCF. By using protoplast of motor cell, we found 35kDa membrane protein strictly recognizes the stereochemistry of LCF, and it is highly likely that the protein is the specific receptor for LCF.
