The light-harvesting core-complex and the B820-subunit from Rhodopseudomonas marina. Part I. Purification and characterisation

• Published in: FEBS letters 1992-10, Vol.311 (2), p.128-134
• Main Authors: Meckenstock, Rainer U., Brunisholz, René A., Zuber, Herbert
• Format: Article
• Language: English
• Subjects: B820; B820 subunit; B860; B873; B880; bacteriochlorophyll; Bacteriochlorophyll α; BChl; characterization; Circular Dichroism; core-antenna complex with an absorption maximum at 880 nm; core-antenna without carotenoids and an absorption maximum at 873 nm; core-complex which was reassociated from B820 and has its absorption maximum at 860 nm; Detergents; Electrophoresis, Polyacrylamide Gel; kDa; kiloDalton; lauryl-N,N-dimethyl-amine-N-oxide; LDAO; LDS; Light-harvesting complex; light-harvesting proteins; lithium dodecyl sulfate; Molecular Weight; n-octyl-β-glucoside; near infra-red; NIR; Non-sulfur purple bacteria; PAGE; Photosynthetic Reaction Center Complex Proteins - chemistry; Photosynthetic Reaction Center Complex Proteins - isolation & purification; polyacrylamide gel electrophoresis; purification; reaction center; Rhodo pseudomonas marina; Rhodopseudomonas; Rhodopseudomonas - chemistry; Rhodospirillaceae; Solubility; Spectrometry, Fluorescence; Spectrum Analysis; subcomplex with an absorption maximum at 820 nm; Tris; tris[hydroxymethyl]aminomethane
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(92)81383-W

The BChla-containing B880-complex (core-complex) of Rhodopseudomonas marina ( Rhodospirillaceae) was isolated with a new purification method. The isolation of the B880-complex was performed by solubilisation of the photosynthetic membranes with the detergent LDAO and subsequent fractionated ammonium-sulfate precipitation with about 50% recovery. The B880-complex retained its original spectral properties as revealed with absorption, fluorescence and circular dichroism spectroscopy. Furthermore, we dissociated the B880-complex with the detergent n-octyl-β-glucoside (OG) and purified the developed subcomplex by the method of Miller et al. [1], which showed an absorption maximum at 820 nm (B820). The α- to β-polypeptide ratio and the α- or β-polypeptide to BChla ratio, respectively, were estimated to be 1:1 in both complexes. The molecular weights of the B880 and the B820-complexes, determined by gel filtration chromatography, were 181 and 32 kDa, respectively. Thus, it appears that the B880-complex of RP. marina consists of 24 polypeptides and the B820-complex of four polypeptides. Six B820-complexes or possible subunits could form the B880-complex. On the basis of these data we propose a model for the structure or BChla containing core-complexes.