RAPID PURIFICATION OF PLANT PLASMA-MEMBRANE K-ATPASE ON A PHOSPHOCELLULOSE COLUMN(,MG2+)

Plasma membrane K+,Mg2+-ATPase with high specific acitivity was purifi ed from soybean (Glycine max L, cv. Williams) hypocotyls. Aqueous poly mer two-phase partition-purified PM vesicles were solubilized by the n on-ionic detergent, C12E8, and P-11 phosphocellulose fibers were used to bind the solubilized ATPase. ATP hydrolyzing enzymes bound to the p hosphocellulose fibers were eluted at 0.6 M NaCl during the step gradi ent elution. The pH dependence of the Mg activation, as well as that o f its K+ stimulation and orthovanadate inhibition of the desalted and concentrated ATP-hydrolyzing fractions was identical to those obtained with the purified PM vesicles. The specific activity, however, was ab out 20 times higher in the fractions containing the partially purified enzyme than with the phase partition purified PM vesicles. This value was proportional to the protein yield of purification.