Coenzyme Q: a molecular orbital study.

The molecular structure and electronic properties of coenzyme Q, also known as ubiquinone, have been studied with the methods of semiempirical molecular orbital theory. It is found that the preferred conformation of the isoprene unit is such that formation of the chroman is favorable. The methoxy groups then assume a nonplanar configuration. Orbital energies, dipole moments, and spectra for the coenzyme Q₁ molecule and some of its chroman intermediates are also given in the calculations. The possibility of charge-transfer complex formation of chroman intermediate with inorganic phosphate is discussed.