The energy-linked carotenoid band-shift in Chromatium vinosum.

Chromatium vinosum chromatophores contain an energy-linked pyrophosphatase that is insensitive to oligomycin and dicyclohexylcarbodiimide. Pyrophosphate hydrolysis produces a carotenoid band-shift similar to that resulting from illumination. The carotenoid band-shift can also be produced by a K⁺ diffusion potential (interior positive) and the magnitude of the band shift is proportional to the membrane potential over at least a 100-fold variation in K⁺ concentration. The light-induced carotenoid band-shift in whole cells is identical to that seen in chromatophores but K⁺ diffusion potentials (interior positive) produce a mirror image of the light-induced band-shift. These results are interpreted in terms of chromatophores being inside-out vesicles.