Imamoto Y, Imai H, Yoshizawa T, Shichida Y
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
FEBS Lett. 1994 Nov 7;354(2):165-8. doi: 10.1016/0014-5793(94)01112-5.
The thermal reaction of meta I-intermediate of iodopsin (metaiodopsin I), a chicken red-sensitive cone pigment, was studied by low-temperature spectrophotometry at -20 degrees C. Irradiation of iodopsin at -20 degrees C produced metaiodopsin I, whose absorption maximum was at about 470 nm. An incubation of metaiodopsin I at -20 degrees C resulted in a conversion to metaiodopsin II having absorption maximum at about 380 nm, as well as a concurrent formation of a red-shifted product stable at room temperature. Since the absorption spectrum and photo-reactivity of the red-shifted product were identical with those of iodopsin, the red-shifted product should be iodopsin. Thus a part of metaiodopsin I can revert to iodopsin by the thermal reaction unlike metarhodopsin I.
