Sedimentation equilibrium experiments were performed on the cryo [kappa]-light chain protein that had been preequilibrated in the no-salt buffer and run at 6000 and 12 000 rpm at 20[degrees]C (analysis could not be performed at 4[degrees]C because of protein precipitation at higher concentrations).
It is possible that there are both salt- and temperature-dependent changes at 20[degrees]C and that only the salt-dependent changes in polymerization are detected by either sedimentation equilibrium or by the apparent [M.sub.r] measured by gel filtration at 4[degrees]C.
For sea urchin larvae, [[rho].sub.N] = 1.01, [[rho].sub.P] = 1.04, and [[rho].sub.i] = 1.03 and 1.03 g * [cm.sup.-3], for gastrula and pluteus, respectively (values were obtained by sedimentation equilibrium experiments; data not shown), and [[eta].sub.P]/[[eta].sub.N] = 1.07.
Fukui and Asai (1980) reported that Triton-treated immobilized cells oriented mostly upwards at the sedimentation equilibrium in sucrose density gradient.
It should be noted, however, that the results of the sedimentation equilibrium experiments were ascribed only to the function of the gravity-buoyancy model and not to the contribution of the drag-gravity model, since [F.sub.H] = 0 with buoyancy artificially balanced with gravity.
Sedimentation equilibrium. Sedimentation experiments on the [lambda] light chain complex purified by SEC were performed using the Beckman Optima XL-1 analytical ultracentrifuge.
The sedimentation equilibrium analysis of the serum sample, performed in the presence or absence of DTT, revealed a molecular mass of ~128 kDa (Table 2).