Biomaterial Database

Sidedness of membrane structures in Rhodopseudomonas sphaeroides. Electrochemical titration of the spectrum changes of carotenoid in spheroplasts, spheroplast membrane vesicles and chromatophores. 1977

K Matsuura, and M Nishimura

The shift of the carotenoid absorption spectrum induced by illumination and valinomycin-K+ addition was investigated in membrane structures with different characteristics and opposite sidednesses isolated from Rhodopseudomonas sphaeroides. Right-side-out membrane structures were prepared by isotonic lysozyme-EDTA treatment of the cells (spheroplasts) and by hypotonic treatment of spheroplasts (spheroplast membrane vesicles). Inside-out membrane structures ("chromatophores") were obtained by treating spheroplast membrane vesicles by French press or sonication. The membrane structures with either sidedness showed the same light-induced change of the "red shift" type. However, the absorbance change by K+ addition in the presence of valinomycin in the right-side-out membrane structures were opposite to that in the inverted vesicles, "blue shift" in the former and "red shift" in the latter. The carotenoid absorbance change was linear to membrane potential, calculated from the concentration of KCl added, with a reference on the cytoplasmic side, through positive and negative ranges.

UI	MeSH Term	Description	Entries
D008027	Light	That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.	Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D002338	Carotenoids	The general name for a group of fat-soluble pigments found in green, yellow, and leafy vegetables, and yellow fruits. They are aliphatic hydrocarbons containing 4 terpene subunits.	Carotenes,Carotenoid,Tetraterpene Derivatives,Tetraterpenes,Carotene,Derivatives, Tetraterpene
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D012242	Rhodobacter sphaeroides	Spherical phototrophic bacteria found in mud and stagnant water exposed to light.	Rhodopseudomonas sphaeroides,Rhodobacter spheroides,Rhodopseudomonas spheroides
D013010	Sonication	The application of high intensity ultrasound to liquids.	Sonications
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D013104	Spheroplasts	Cells, usually bacteria or yeast, which have partially lost their cell wall, lost their characteristic shape and become round.	Spheroplast
D013816	Thermodynamics	A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)	Thermodynamic