FIGURE 3.

Sedimentation velocity of H⁺,K⁺-ATPase. Experiments were done at 42,000 rpm and 7 °C for different fractions of the main H⁺,K⁺-ATPase peak from gel filtration. The solvent was 40 mm KCl, 40 mm MES buffer (pH 6.0), 3 mm Mg²⁺, 1 mm EDTA, 0.25 m sucrose, 2 mg/ml Tween 20. A and B, superposition, for the central fraction, of selected experimental and fitted profiles (top panels) and of their differences (bottom panels) obtained at 280 nm (A) and using interference optics (B). The last profiles correspond to 14 h of sedimentation. C, superposition of the c(s) distributions obtained in the range of 0.1–10 S from the two optics for (from top to bottom) the first, central, and last fractions of the main peak. D, evolution of the content of the fractions from gel filtration along the main peak of H⁺,K⁺-ATPase, evaluated from the area under the c(s) curve from the data at 280 nm. In this last panel, the sedimentation coefficients are given as s_20,w.