Evidence that a light-accelerated abrupt change in membrane characteristics of bovine rod outer segment fragments takes place at acidic pH |
| |
Authors: | Masato Watanabe Toshifumi Taira Hiroshi Asai |
| |
Institution: | Department of Physics, Waseda University Tokyo 160, Japan |
| |
Abstract: | Changes in the turbidity of suspensions of bovine rod outer segment fragments induced by rhodopsin bleaching were measured in the presence of various concentrations of divalent cations at acidic pH (4.7–5.4). Unlike the situation at neutral pH, the turbidity of the suspensions increased drastically by bleaching at acidic pH. It was found that the extent of turbidity change became maximum at a particular concentration of divalent cations (i.e., 5 mM CaCl2, 5 mM MgCl2, or 5 mM mixed divalent cations). However, the turbidity increment in the presence of 5 mM MgCl2 was greatly enhanced by the addition of a minute amount of CaCl2. These results evidently show that the membrane characteristic is abruptly changed by bleaching at acidic pH in particular. It is also suggested that there are two kinds of binding sites for Ca ions: one is a Ca2+ specific site, and the other is a nonspecific site to which Mg2+ can also bind. |
| |
Keywords: | ROS rod outer segment |
本文献已被 ScienceDirect 等数据库收录! |
|