Effect of chloride ion on the thermal decay process of the batho intermediate of iodopsin at low temperature

Publisher Website
Google Scholar
Abstract
The photochemical and the subsequent thermal behaviors of iodopsin (Cl-bound form) and N-iodopsin (iodopsin whose Cl- was replaced by NO3-) in CHAPS-phosphatidylcholine (PC) were studied by low-temperature spectrophotomery. Irradiation of the iodopsin preparation at -185.degree. C produced a photo-steady-state mixture composed of iodopsin, bathoiodopsin, and isoiodopsin. Bathoiodopsin was thermally reverted to the original iodopsin. These results were almost the same as those reported previously [Yoshizawa, T., and Wald, G. (1967) Nature 214, 556-571] in which iodopsin was extracted with 2% digitonin. Therefore, photochemical and subsequent thermal behaviors of iodopsin were independent of the detergent to solubilize iodopsin. Irradition of N-iodopsin at -185% C produced the similar photo-steady-state mixture. However, N-bathoiodopsin was thermally converted to the next intermediate, presumably N-lumiiodopsin. These results suggest that the batho-lumi transition of iodospin at low temperature is likely to be inhibited by the Cl- bound to the protein moiety of iodopsin, while at room temperature the Cl- bound to iodopsin could be released on the conversion process of batho- to lumiiodopsin.

This publication has 5 references indexed in Scilit: