Characterization of the ( in a membranous preparation from the optic ganglion of the squid (Loligo pealei) |
| |
Authors: | GE Breitwieser |
| |
Institution: | Department of Physiology and Biophysics, Washington University Medical School, St. Louis, MO 63110 U.S.A. |
| |
Abstract: | (1) A membrane fraction enriched in (EC 3.6.1.3) was obtained from optic ganglia of the squid (Loligo pealei) by density gradient fractionation of membranes followed by treatment with either SDS or Brij-58. The resulting membrane had an specific activity of approx. 2 units/mg and was ouabain-sensitive. (2) The had a for ATP of and a pH optimum of 7.0. It was inhibited by ouabain with a of . (3) Optimum monovalent cation concentrations were: 240 mM NaCl, 60 mM KCl, tested with . (4) The Mg2+ dependence of hydrolysis varied with the absolute ATP concentration. At 3 mM ATP, the for Mg2+ was , and at 6 mM ATP, the was . High levels of Mg2+ caused inhibition of hydrolysis. (5) The interactions of Na+ and K+ were examined over a range of conditions. K+ levels caused modulations in the Na+ dependence in the range of 1–150 mM. (6) The prepared from squid optic ganglion displays properties similar to those of the sodium pump in injected nerves. |
| |
Keywords: | Membrane fractionation (Squid optic ganglion) |
本文献已被 ScienceDirect 等数据库收录! |
|