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'Bacteriorhodopsin' in keywords Facet   section ZfN Section C  [X]
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2000 (1)
1979 (1)
1Author    Nikolai Tuparev, Anelia Dobrikova, Stefka Taneva, Tzvetana LazarovaRequires cookie*
 Title    Bacteriorhodopsin Thermal Stability: Influence of Bound Cations and Lipids on the Intrinsic Protein Fluorescence  
 Abstract    Temperature -induced changes in protein intrinsic fluorescence of native, delipidated and deionized purple membranes are investigated. It is found that the removal of cations most strongly affects the protein and its thermal stability. The denaturation of dei-BR completes at 70 °C, while delipidated and native BR still maintain their native structure at this temper­ ature. Both, the quantum yield and the fluorescence maximum suggest correlation between the Trp-retinal coupling and protein structural stability. The low red shift of the fluorescence maximum caused by increasing of temperature indicates limited unfolding of bacteriorhodop­ sin upon denaturation. 
  Reference    Z. Naturforsch. 55c, 355—360 (2000); received December 27 1999/February 23 2000 
  Published    2000 
  Keywords    Bacteriorhodopsin, Deionization, Delipidation 
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 TEI-XML for    default:Reihe_C/55/ZNC-2000-55c-0355.pdf 
 Identifier    ZNC-2000-55c-0355 
 Volume    55 
2Author    N. Orbert, A. Dencher, Eilo HildebrandRequires cookie*
 Title    Sensory Transduction in Halobacterium halobium: Retinal Protein Pigment Controls UV-Induced Behavioral Response  
 Abstract    Both photosystems, PS 370 and PS 565, controlling behavioral responses in H alobacterium halo-bium [E. Hildebrand and N. Dencher, Nature 2 5 7 ,4 6 — 48 (1975)] are reversibly inhibited when bacteria are grown in the presence o f 1 mM nicotine which is known to block biosynthesis o f reti­ nal. Photobehavior can be restored within som e minutes to hours by adding retinal to nicotine-treated bacteria, PS 370 thereby reappearing earlier than PS 565. The reconstitution rate depends on the concentration and on the kind o f retinal isomers applied. A \\-trans retinal is m ost effective. PS 370 becomes fully sensitive if reconstituted in the presence o f nicotine. This rules out the possi­ bility that the alkaloid may directly inhibit steps o f signal transmission follow ing photoreception. The action spectrum o f PS 370 regenerated with retinal alone o f H. h., strain RjLg (a mutant deficient in carotenoids), fails to show all secondary peaks around 450 nm which in strain Rj occur besides the prominent maximum at 370 nm. A ddition o f carotenoids (m ainly a-bacterioruberin) to reconstituted cells o f R ,L3 restores the sensitivity in that spectral region. Carotenoids or flavin solely added to nicotine-treated bacteria cannot restore photobehavior. We conclude that the active pigm ent o f PS 370, which m ediates the photophobic response to increase o f light intensity (step-up response), represents a retinal protein com plex and that carote­ noids participate in photoreceptor function as accessory pigments. The biochem ical relation o f the UV-absorbing retinal protein com plex to bacteriorhodopsin is discussed. 
  Reference    Z. Naturforsch. 34c, 841 (1979); received June 5/July 6 1979 
  Published    1979 
  Keywords    Bacteria, Photophobic Response, Bacteriorhodopsin, Carotenoids, Accessory Pigment 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0841.pdf 
 Identifier    ZNC-1979-34c-0841 
 Volume    34