As part of an on-going program of study of the physicochemical properties of interacting macromolecules in solution, it is proposed to (1) continue our studies on the interaction of phenothiazine tranquilizing drugs with brain tubulin with particular emphasis on determination of the binding constants of chlorpromazine, trifluoperazine and the control drug promethazine by the method of fluorescence quenching; (2) continue our CD and 13C NMR investigation of the solution conformation of bradykinin, Lys-Lys-Lys and model compounds; and (3) extend our theoretical calculations on the mass transport of interacting macromolecules to include the analytical sedimentation of antigen-antibody complexes.