Pigment composition and optical rotatory dispersion of chloroplast fractions obtained by detergent action.

Plant photosynthesis is considered to consist of photochemical reactions originating from 2 separate pigment systems. Fractionation of the 2 photochemical systems has been demonstrated only recently by detergent treatment of spinach chloroplasts followed by di fferential centri ftugation ( 1, 9). This study shows that the light and heavy fractions obtained by either digitonin or Triton X-100 treatment have a characteristic distribution not only in the chlorophylls but also in the carotenoids. Some correlation between the pigment composition and the absorption and optical-rotatory-dispersion (ORD) spectra is also presented. Chloroplast fragmentation and separation were carried out by the same procedures described previously (1, 9). The chlorophylls and carotenoids