Effect of anions on the quaternary structure of Biomphalaria glabrata hemoglobin at pH 3.0

1. The effect of different ions on the state of aggregation of B. glabrata hemoglobin at pH 3.0 was investigated by analytical ultracentrifugation. 2. Low salt concentration induced aggregation of the protein subunits at this pH. There was an exponential dependence of the sedimentation coefficient on salt concentration. 3. The aggregating effect was primarily due to the anion and was abolished when the protein was treated with maleic anhydride. 4. The effectiveness of anions in inducing aggregation was: SO2-4 > SCN- > CH3- COO- > CF3-COO- >CL-. 5. tThe observed phenomena are not explained either by the Debye-Hückel theory or by a disturance of the protein hydration shell