A RADIOTRACER STUDY OF RARE EARTH BINDING MEMBRANE PROTEIN OF TETRAHYMENA PYRIFORMIS. Ⅱ, PROPERTIES OF Yb BINDING MEMBRANE PROTEIN

Yb binding membrane protein of tetrahymena pyriformis was isolated in considerable amount.The average dissociation constant and the average binding site number of the Yb-protein complex were determined as (4.2±0.1)×10~(-6) mol/l and 3.4±0.7 respectively by equilibrium dialysis experiment and concomitant Scatchard-type diagram.Hence, the apparent stability constant of this complex is around 2.4x10~5l/mol, or 1gK=5.4.No apparent difference on the aminoacid composition between Yb binding protein and corresponding non-Yb binding protein was observed.