FIG. 4.

Sedimentation equilibrium of P15 (A) and P3 (B). For each oligomeric protein, nine data sets, with three initial concentrations and three different speeds, were obtained and globally fitted to a single-species model. The rotor speeds were 5,000, 7,000, and 9,000 rpm, and the initial loading absorbance values at 280 nm were 0.1, 0.3, and 0.5 for P15 and 0.2, 0.4, and 0.6 for P3, respectively. A concentration profile for P15 (initial absorbance of 0.3 at 280 nm, measured at 9,000 rpm) (A) and that for P3 (initial absorbance of 0.6 at 280 nm, measured at 5,000 rpm) (B) are shown. The obtained molecular weights were 196,200 ± 4,300 for P15 and 119,100 ± 3,300 for P3, respectively, indicating that both complexes are homohexamers.