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At least 811 records · Page 45Linked to original sources
PubMed1980

Analysis of the irreversible process of proton transport in the purple membrane of Halobacterium halobium.

The proton transport across biological membrane, accompanied by energy transformation, is closely related with many basic processes involved in the maintenance of life. Active researches are carried out in this field, but so far we have not known a complete calculation. This paper presents a model of an open and closed photon-controlled ion pore with a quantitative analysis of the irreversible process of the proton transport across the purple membrane. Upon absorbing photon by the purple membrane, the deprotonation of the Schiff base causes the ion pore to open, but it will close when it returns to bR570. A set of nonlinear differential equations describing this model is given. The stability of the equations is discussed. The results of the numerical calculation for steady state are found in good agreement with the experimental data of Bakker.

Bacteriorhodopsins↗
PubMed1984

Long time stability of purple membranes from Halobacterium halobium.

The fast component of the electrical signal and the light absorption signals at different resolution times (at lambda = 408 nm) in an untreated purple membrane suspension were measured in order to study the stability of purple membrane fragments. It has been established that there is no change in the rate constants of L----M and M----O transitions of the photocycle in either the electrical or the light absorption signals of purple membrane suspension kept at 4 degrees C for up to 40 days. Moreover, also the amplitudes of the I (negative) and II (positive) components of the electrical signal remained unchanged during this period.

Bacteriorhodopsins↗
PubMedDate not supplied

[Spectral transformations in purple membranes of Halobacterium halobium: effect of 560-570 transition and blue light on photochemical processes].

Effect of reversible photodependent spectral transition 560 in equilibrium 570 of the basic absorption band in purpur membranes (PM) in water on the accumulation of short-living forms 412 and 650 of bacteriorhodopsin (BR) photochemical cycle was studied. It has been shown that photochemical transformations in BR proceed as a minimum by two independent cycles, whose initial spectral forms were represented by BR with retinene in the form 13 cis and BR with retinene in the form of trans. In the course of the transition 560-- greater than 570 a long-living spectral form 370--410--430 sensitive to the blue light is formed. On the basis of our own and literature data a new scheme of photochemical processes in PM was suggested and connection between some stages of these processes and ejection and absorption of PM protones proposed.

Bacteriorhodopsins↗
PubMedDate not supplied

[Lipid composition of Halobacterium cells and bacteriorhodopsin isolated from them].

The phospholipids qualitative and quantitative compositions were determined in halobacteria cells and in bacteriorodopsin isolated from them. The phospholipid composition of the cells and bacteriorodopsin is established to be unstable and to depend on the cells cultivation conditions and the culture strain.

Bacteriorhodopsins↗
PubMed1994

[Plasmid from Halobacterium halobium and its restriction map].

In this paper, ten strains of H. halobium were screened for the occurrence of plasmid by four methods. Six of the strains harbored plasmids of high molecular weight. Of all the detecting methods, the TENS method was the best for H. halobium. J7 strain contains only one type of plasmid named as pHH205 which showed stationary CCC form. The highest copy number of the plasmid was observed in late stationary growth phase, which was approximately 49 copies per cell. The molecular weight is 16.7kb. The sites of five endonucleases had been determined for pHH205 and three of them, namely BamHI, HindIII and XbaI, were single sites neighboring to each other.

Halobacterium salinarum↗
PubMed1997

High-salt effects on the structure and damage of chromosomal DNA in Halobacterium salinarium, an extremely halophilic bacterium.

High concentration salt effects on the structure and radiation-induced damages of DNA were studied to elucidate the biochemical mechanism of the resistance of halophilic H. salinarium against DNA damaging agents. High concentration of KCl did not induce significant conformational changes in H. salinarium chromosomal DNA, but exhibited an extensive protective effect on the radiation-induced single-strand breaks of plasmid DNA.

Chromosomes, Bacterial↗