Isolation and purification of reaction center from Rhodopseudomonas viridis NHTC 133 by means of LDAO

Abstract

Two different procedures are described to isolate and purify the reaction center complex from Rhodopseudomonas viridis NHTC 133 by means of the non-ionic detergent dodecyldimethylamine oxide. Both reaction center particles thus obtained were active, as shown by a photobleaching centered at 975 nm. The reaction center also contained, in addition to bacteriochlorophyll, bacteriopheophytin. Other components were also found in this particle: cytochromes C553 and C558 and a menaquinone-like substance. The SDS gel electrophoresis of reaction centers is shown. The molecular weights of the subunits forming the reaction center in 0.5% sodium dodecyl sulfate and 1% mercaptoethanol were calculated as being: 45 +/- 1.5 and 37 +/- 1.5 kdalton, 29 +/- 1.5 and 23 +/- 1.5 kdalton. The molecular weight of the complex determined by means of gel filtration (Sepharose 6-B and Bio-Gel P-300) gives a value of approximately 240 kdalton. The minimum molecular weight of the complex calculated by disc gel electrophoresis was 231 kdalton.