Heterogeneity of the thylakoid membrane fractions derived from spinach chloroplasts by the action of Triton X-100 in low salt medium: II, isolation of β-carotene by the DEAE cellulose column chromatography

Abstract

Treatment of spinach chloroplast lamellae with 1% Triton X-100 without prior incubation in salt medium leads not only to the appearance of different types of chlorophyll-protein particles [4] but also to release of a certain amount of β-carotene. This latter pigment can be satisfactorily separated on a DEAE cellulose column on washing with 0.5 M NaCl. The isolated β-carotene is devoid of other photosynthetic pigments and exhibits a red-shifted absorption spectrum by approximately 50 nm in an aqueous medium as compared to that in light petroleum. Pure β-carotene (and some of the pure xanthophylls) is also adsorbed on DEAE cellulose when it is applied to the column in Tris-HCl buffer (0.05 M, pH 7.4) containing Triton X-100 (0.5%) and/or bovine serum albumin (0.5 mg ml −1). However its absorption spectrum differs from that of the β-carotene form released from chloroplast lamellae by incubation with Triton X-100. We found only a small amount of protein to accompany β-carotene isolated from the lamellae with aqueous solvent, and therefore we suppose that the aggregated free pigment occurred in the aqueous medium containing Triton X-100. However, the occurrence of caroteneprotein complexes with a small protein moiety could not be excluded.