Effect of TPI binding to IOV on the isomerase activity in the absence and presence of salt or anti-band 3 antibody. IOVs were washed twice and then resuspended with 50 μl of the corresponding diluted hemolysates (hemoglobin contents: 6.8 g/liter and 3.0 g/liter for propositus and control, respectively). The hemolysates were diluted with buffer A or with buffer A containing 100 mM KCl. The suspensions were incubated for 30 min at 25°C in the presence or absence of 10 μl antibody raised against the N-terminal sequence of band 3. Then, the whole sample was used for TPI assay as described in Materials and Methods. The standard error of the determinations was ± 20% (n = 3). Samples: Normal: 1, control (no IOV); 2, 50 μg IOV; 3, 50 μg IOV + 10 μl anti-band 3 antibody; 4, 100 μg IOV; Propositus: 1, control (no IOV); 2, 100 μg IOV; 3, 100 μg IOV+ 100 mM KCl.