Localization of photosynthetic membrane components in Rhodopseudomonas sphaeroides by a radioactive labeling procedure

Journal Article · Tue Oct 28 04:00:00 EST 1980 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00563a026· OSTI ID:5764840

Francis, G A; Richards, W R

Reduction with (3H)KBH4 of Schiff's bases generated by reaction with pyridoxal 5'-phosphate yields tritium-labeled derivatives of both proteins and lipids accessible on the periplasmic side of the cytoplasmic membrane. Application of this technique to phototrophically grown Rhodopseudomonas sphaeroides labeled both the cell envelope and chromatophore fractions. The technique was also applied to R. sphaeroides harvested at various times during an adaptation from heterotrophic to phototrophic growth conditions. The specific activity of the chromatophore fraction after 20 h of adaptation was 76% of that found at the beginning, indicating that the intracytoplasmic membranes and cytoplasmic membrane form a continuous membrane system, with the majority of the intracytoplasmic membranes acessible to the external medium throughout the adaptation. The identity of the proteins labeled by this technique was investigated in two fractions labeled after cell disruption: normal inside-out chromatophores and right-side-out membrane vesicles isolated by lysozyme - osmotic shock treatment of cells grown in high light intensity. The results after sodium dodecyl sulfate - polyacrylamide gel electrophoresis and fluorography indicated that the 28000-dalton subunit of the reaction center complex and two polypeptides in the light-harvesting region of the gel were heavily labeled in the chromatophores and were thus accessible on the cytoplasmic side of the membrane. At least one of the latter two polypeptides was also labeled in the membrane vesicles and was thus also accessible on the periplasmic side of the membrane. None of the reaction center subunits was significantly labeled in a reaction center complex prepared from the membrane vesicle sample.

• OSTI ID: 5764840
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 19:22; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
550301 -- Cytology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BIOCHEMISTRY
CELL CONSTITUENTS
CELL MEMBRANES
CENTRIFUGATION
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHEMISTRY
ELECTROPHORESIS
LABELLED COMPOUNDS
MEMBRANES
MICROORGANISMS
MORPHOLOGY
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PROTEINS
QUANTITATIVE CHEMICAL ANALYSIS
RHODOPSEUDOMONAS
SEPARATION PROCESSES
STRUCTURAL CHEMICAL ANALYSIS
SYNTHESIS
TRITIUM COMPOUNDS