Optical properties of complexes of antimalarial drugs with ferriprotoporphyrin IX in aqueous medium. I. The system ferriprotoporphyrin IX-quinine.
Circular dichroism (CD) and light-absorption spectra of the system ferriprotoporphyrin IX-(-)-quinine as measured at 26 to 27 degrees C in dilute aqueous solutions of both pH 7.4 and 11.5 are reported. The CD spectra changed significantly with time during measurements extending for many days. By CD titrations, a predominant mole ratio of 1:1 in the complex is indicated. Sedimentation velocity and viscosity measurements, carried out under similar conditions, suggest the formation of large and specific aggregates at both pH 7.4 and 11.5-12. The large CD bands observed in the Soret region indicate chiral interactions between FP molecules arrayed within aggregates of FP-Q complexes. The observed time dependence of the ellipticities is considered to be due to dynamic changes in the steric arrangement of interacting units within the aggregates.
D002942:Circular Dichroism; D006418:Heme / Q000031:analogs & derivatives; D006427:Hemin; D006863:Hydrogen-Ion Concentration; D007477:Ions; D011803:Quinine; D013057:Spectrum Analysis; D014461:Ultracentrifugation
D007477:Ions; D006418:Heme; D006427:Hemin; D011803:Quinine