Carotenoid Absorbance Changes in Liposomes Reconstituted with Pigment-Protein Complexes from Rhodobacter Sphaeroides

Abstract

The electrochromic behaviour of carotenoids has been widely used to determine the electrical potential difference (∆ψ) across photosynthetic membranes, like chromatophores [1] and bacterial cells [2,3]. The carotenoid absorbance change has several advantages over other methods for recording the ∆ψ: (i) the method is non-invasive, (ii) the relationship between the ∆ψ and the absorbance change is linear and (iii) the method shows a rapid response time. The major disadvantage of the carotenoid band shift as a ∆ψ indicator is that a calibration of the ∆ψ dependent bandshifts is not (always) possible in every experimental system [3].