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Circular dichroism of ferriprotoporphyrin IX-morphine complexes in aqueous solution
1Department of Biological Chemistry, Hebrew University of Jerusalem, Israel.
Archives of Biochemistry and Biophysics
|January 10, 1995
Summary
Ferriprotoporphyrin IX (FP) forms optically active complexes and aggregates with (-)-morphine. This optical activity, observed between 300-450 nm, is pH-dependent and arises from chiral FP molecule interactions within aggregates.
Area of Science:
- Biophysical Chemistry
- Supramolecular Chemistry
Background:
- Ferriprotoporphyrin IX (FP) is a key heme component.
- (-)-Morphine is a well-known opioid alkaloid.
Purpose of the Study:
- To investigate the formation and properties of complexes between ferriprotoporphyrin IX and (-)-morphine.
- To characterize the optical activity and aggregation behavior of these complexes.
Main Methods:
- Circular Dichroism (CD) spectroscopy to measure optical activity.
- Ultracentrifugation to determine aggregate formation.
- CD titration to estimate mole ratios.
Main Results:
- FP-(-)-morphine complexes exhibit significant optical activity, with a major CD band at 364 nm.
- Optimal optical activity occurs within a pH range of 7.4 to 7.8.
- Complex formation is accompanied by the formation of large aggregates.
- A 1:1 mole ratio of FP to morphine in the complex was determined.
- Morphine derivatives like heroin and codeine did not form similar optically active complexes.
Conclusions:
- The observed optical activity in FP-(-)-morphine complexes likely originates from chiral interactions among FP molecules within aggregates.
- Aggregation and optical activity are linked phenomena in these systems.
- The specificity of complex formation highlights the unique structural contributions of (-)-morphine.