共查询到20条相似文献,搜索用时 31 毫秒
1.
Hampp NA 《Applied microbiology and biotechnology》2000,53(6):633-639
Bacteriorhodopsin (BR) is the key protein for the halobacterial photosynthetic capabilities and is one of the very rare molecules
which occur in crystalline form in nature. Since its discovery, which was reported in 1971, many efforts have been made to
exploit the obvious technical potential of this molecule. Successful application of gene technology methods for the modification
of the physical function of a biomolecule was first demonstrated with BR. This approach points the way to a new class of materials
derived from evolutionary optimized biomaterials by genetic re-engineering. Mutated BRs proved to have significant advantages
over the wild type in optical applications. The current status of potential technical applications of BR is reviewed. BR is
employed as a photoelectric, photochromic or energy-converting element. First systems now exist which demonstrate the successful
integration of this new material into existing technologies. Analyzing the patents filed, which claim the processing or application
of BR, gives an indication to areas where further technical uses are to be expected in the near future.
Received: 16 November 1999 / Received revision: 3 December 1999 / Accepted: 3 December 1999 相似文献
2.
The photochromic properties of bacteriorhodopsin (BR), in addition to its longevity and excellent reversibility, are attractive features for the construction of light-sensitive media for optical information processing. However, the various optical techniques require media with specifically adapted and widely differing properties. Genetic engineering of BR and biotechnological production of mutated BRs is the key for the utilization of this photochromic compound in optical applications. Mutated BRs, generated by single and double amino acid exchanges, have been used as recording media for optical applications such as phase conjugation or long-term data storage at room temperature. 相似文献
3.
The organic carbon consumed by aquatic bacteria (BCC) is partitioned between bacterial production (BP) and respiration (BR), but the factors that determine BCC and its partition into BP and BR are not well understood. We explored the coupling between BR, BR and BCC, and their links to dissolved organic carbon (DOC) and nutrient availability in natural and restored tidal marshes and in the adjoining waters of Delaware Bay estuary. Labile DOC (LDOC) ranged from 3% to 22% of the DOC pool, and explained more of the variance in both BR and BCC than did bulk DOC. Bacterial growth efficiency (BGE) was highly variable (0.09-0.58), and natural Spartina alterniflora marshes had consistently higher BGE than both restoration marshes and tidal floodwaters. BGE was negatively related to the ratio of LDOC to total dissolved phosphorous, which was highest in natural marshes. The enhancement of BP observed in the marshes relative to the estuarine floodwaters had different origins: In natural marshes it was mostly due to increases in BGE, whereas in restored marshes it followed increased BCC. These results highlight the importance of P in regulating microbial metabolism in coastal areas, and the need to understand the pathways that lead to BP in these systems. 相似文献
4.
An efficient system for the synthesis of bacteriorhodopsin in Halobacterium halobium 总被引:19,自引:0,他引:19
The mechanism by which bacteriorhodopsin (BR) transports protons across the cell membrane of Halobacterium halobium is actively studied in many laboratories. Currently available systems for the synthesis of mutant proteins obtained by site-directed mutagenesis of the gene encoding BR (bop) require reconstitution of the denatured polypeptide after its synthesis Escherichia coli or yeast; this approach is technically difficult and labor intensive, and raises questions about possible differences between in vivo and in vitro folding. Using a newly described transformation system and a halobacterial plasmid vector, we show that it is possible to reintroduce the bop gene into BR- strains of H. halobium. The bop-carrying plasmid expresses native BR in amounts similar to those obtained in several wild type strains. This system allows facile site-directed mutagenesis in halophilic archaebacteria. 相似文献
5.
Bacteriorhodopsin (BR) is an integral membrane protein found in "purple membrane" (the Archaea cell membrane) mainly in Halobacteria. This protein absorbs green light (wavelength 500-650 nm, with the absorption maximum at 568 nm) and converts it into an electrochemical gradient. This gradient in turn is used for ATP production. The ability of BR to convert light energy into chemical energy or sunlight into electricity has been used in different applications mainly optical appliances but also for therapeutic/medical applications and research. This review surveys some of these applications that have been patented in the last five years. 相似文献
6.
A study of the interface strength between protein and mineral in biological materials 总被引:2,自引:0,他引:2
Ji B 《Journal of biomechanics》2008,41(2):259-266
Bone, tooth, mineralized tendon and sea shells are nanocomposites of protein and mineral with superior mechanical properties. As the mineral is so small at nanoscale, the volume fraction of the protein-mineral interface in the bulk materials can be enormously large; therefore, the mechanics of the interface should be critically important for the integrity of these biomaterials. Currently, people do not have a good understanding of the interface between protein and mineral, a hybrid interface between organic and inorganic constituents in biological materials. In this paper, a tension-shear chain (TSC) model is introduced into the Dugdale model for estimating the fracture energy of biomaterials. The strength of the hybrid interface is then studied with a "soft-hard" bi-layer fracture model, by which we find for the first time that the interface strength depends on both the size and geometry of the mineral crystal, and has been highly optimized through the miniaturization of mineral at nanoscale. This study may provide important insights into the mechanics of bone and tooth at small scale for tissue engineering in biomedical applications. 相似文献
7.
Color sensitive retina based on bacteriorhodopsin 总被引:3,自引:0,他引:3
Bacteriorhodopsin (BR), a membrane protein of a microorganism Halobacterium salinarium has been studied since the 80's as a potential material for information technology. The information processing applications of BR employ either photochromic or photoelectric properties of the protein. In this study we discuss about design principles and describe our study of the use of bacteriorhodopsin as a sensor material for a color sensitive artificial retina. This retina includes low-level processing of input information. The design of a color sensitive matrix element, the self-organizing color adaptation algorithm and a system model for the retina are presented. 相似文献
8.
9.
Sapra KT Doehner J Renugopalakrishnan V Padrós E Muller DJ 《Biophysical journal》2008,95(7):3407-3418
Bacteriorhodopsin (BR), a specialized nanomachine, converts light energy into a proton gradient to power Halobacterium salinarum. In this work, we analyze the mechanical stability of a BR triple mutant in which three key extracellular residues, Glu9, Glu194, and Glu204, were mutated simultaneously to Gln. These three Glu residues are involved in a network of hydrogen bonds, in cation binding, and form part of the proton release pathway of BR. Changes in these features and the robust photocycle dynamics of wild-type (WT) BR are apparent when the three extracellular Glu residues are mutated to Gln. It is speculated that such functional changes of proteins go hand in hand with changes in their mechanical properties. Here, we apply single-molecule dynamic force spectroscopy to investigate how the Glu to Gln mutations change interactions, reaction pathways, and the energy barriers of the structural regions of WT BR. The altered heights and positions of individual energy barriers unravel the changes in the mechanical and the unfolding kinetic properties of the secondary structures of WT BR. These changes in the mechanical unfolding energy landscape cause the proton pump to choose unfolding pathways differently. We suggest that, in a similar manner, the changed mechanical properties of mutated BR alter the functional energy landscape favoring different reaction pathways in the light-induced proton pumping mechanism. 相似文献
10.
Improving our ability to control capillary morphogenesis has implications for not only better understanding of basic biology,
but also for applications in tissue engineering and in vitro testing. Numerous biomaterials have been investigated as cellular
supports for these applications and the biophysical environment biomaterials provide to cells has been increasingly recognized
as an important factor in directing cell function. Here, the ability of ionic self-assembling peptide gels to support capillary
morphogenesis and the effect of their mechanical properties is investigated. When placed in a physiological salt solution,
these oligopeptides spontaneously self-assemble into gels with an extracellular matrix (ECM)-like microarchitecture. To evaluate
the ability of three-dimensional (3D) self-assembled peptide gels to support capillary-like network formation, human umbilical
vein endothelial cells (HUVECs) were embedded within RAD16-I ((RADA)4) or RAD16-II ((RARADADA)2) peptide gels with various stiffness values. As peptide stiffness is decreased cells show increased elongation and are increasingly
able to contract gels. The observation that capillary morphogenesis is favored in more malleable substrates is consistent
with previous reports using natural biomaterials. The structural properties of peptide gels and their ability to support capillary
morphogenesis in vitro make them promising biomaterials to investigate for numerous biomedical applications. 相似文献
11.
The significance of inspiration from nature for technical textiles and for fibrous composite materials is demonstrated by examples of already existing technical solutions that either parallel biology or are indeed inspired by biological models. The two different basic types of biomimetic approaches are briefly presented and discussed for the "technical plant stem." The technical plant stem is a biomimetic product inspired by a variety of structural and functional properties found in different plants. The most important botanical templates are the stems of the giant reed (Arundo donax, Poaceae) and of the Dutch rush (Equisetum hyemale, Equisetaceae). After analysis of the structural and mechanical properties of these plants, the physical principles have been deduced and abstracted and finally transferred to technical applications. Modern computer-controlled fabrication methods for producing technical textiles and for structuring the embedding matrix of compound materials render unique possibilities for transferring the complex structures found in plants, which often are optimized on several hierarchical levels, into technical applications. This process is detailed for the technical plant stem, a biomimetic, lightweight, fibrous composite material based on technical textiles with optimized mechanical properties and a gradient structure. 相似文献
12.
Photochemical conversion of the O-intermediate to 9-cis-retinal-containing products in bacteriorhodopsin films. 总被引:5,自引:0,他引:5
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The photochemical activity of the O-state was investigated in bacteriorhodopsin (BR) films containing wildtype BR at pH 6.5 in the presence of glycerol. The formation of a photoproduct of O with an absorption maximum at 490 nm and 9-cis-retinal configuration was found. This 490-nm product was named P and shows a slow thermal reaction into a compound with a maximal absorption at 380 nm which was named Q and contains free 9-cis-retinal in the proteins binding site. The photoproducts of O, i.e., P and Q, are very similar, or even identical, to those previously observed in blue membranes. Common to the O-state and blue membrane forms of bacteriorhodopsin is a protonated aspartic acid 85, and we suggest that it is the reduced negative charge around the Schiff base which is responsible for the 9-cis photoisomerization. The release of a proton from aspartic acid 85 is linked to the conversion of the O-state back to the initial state of BR. Therefore the conditions of low proton mobility in BR films containing glycerol favor the accumulation of the O-state. For optical and holographic applications such BR films are very attractive. It is possible to create photoproducts with red light which are thermally stable at room temperature and that can be photochemically erased. Dependent on the light composition both properties can be realized in the same sample material. This feature may bridge the gap between information processing and short-term and long-term storage of information with BR. 相似文献
13.
The present review is devoted to the application of biomaterials from regenerated silk for designing tissue-engineered constructs—the
basis for hybrid organs and tissues. Fibroin, the main structural protein of silkworm silk, can be used to design artificial
cartilages, bone tissue fragments, blood vessels, as well as to regenerate nervous tissue. Fibroin capsules containing bioactive
compounds are successfully applicable in medicinal therapy, such as controlled drug delivery in cancer treatment. Apart from
fibroin, tissue engineering can successfully be based on biopolymer spidroin, a spider net protein, which is also a biocompatible
material with valuable mechanical properties. 相似文献
14.
Dag Brune 《Biological trace element research》1987,13(1):319-331
Nuclear corrosion technique has been developed for the assay of various heavy metals released through corrosion and abrasion
into electrolytes from various biomaterials like amalgams, chromium— cobalt and gold alloys, steel, and titanium. Application
of the technique in measurement of selective release rates under static or dynamic conditions, i.e., during cyclic loading,
is discussed. The elements chromium, cobalt, copper, gold, iron, mercury, molybdenum, silver, titanium, and zinc have been
quantitatively assessed. In vivo corrosion measurements are further included. By combining the present nuclear tracer technique
with ESCA technique, knowledge about reaction mechanisms occurring at the interface solid/liquid is obtained. Exposure of
humans to various heavy metals from biomaterials, e.g., dental materials, can be estimated using the NCM technique. The technique
also has a potential for selective release measurements of several nuclides possessing suitable radioanalytical properties
from other types of alloys immersed in various liquid environments. 相似文献
15.
Ida G. Anemaet Martijn Bekker Klaas J. Hellingwerf 《Marine biotechnology (New York, N.Y.)》2010,12(6):619-629
High oil prices and global warming that accompany the use of fossil fuels are an incentive to find alternative forms of energy
supply. Photosynthetic biofuel production represents one of these since for this, one uses renewable resources. Sunlight is
used for the conversion of water and CO2 into biomass. Two strategies are used in parallel: plant-based production via sugar fermentation into ethanol and biodiesel
production through transesterification. Both, however, exacerbate other problems, including regional nutrient balancing and
the world's food supply, and suffer from the modest efficiency of photosynthesis. Maximizing the efficiency of natural and
engineered photosynthesis is therefore of utmost importance. Algal photosynthesis is the system of choice for this particularly
for energy applications. Complete conversion of CO2 into biomass is not necessary for this. Innovative methods of synthetic biology allow one to combine photosynthetic and fermentative metabolism via the so-called Photanol approach to form biofuel directly from Calvin cycle intermediates through use of the naturally transformable cyanobacterium
Synechocystis sp. PCC 6803. Beyond providing transport energy and chemical feedstocks, photosynthesis will continue to be used for food
and feed applications. Also for this application, arguments of efficiency will become more and more important as the size
of the world population continues to increase. Photosynthetic cells can be used for food applications in various innovative
forms, e.g., as a substitute for the fish proteins in the diet supplied to carnivorous fish or perhaps—after acid hydrolysis—as
a complex, animal-free serum for growth of mammalian cells in vitro. 相似文献
16.
E. Szabó á. Szatmári é. Hunyadi-Gulyás E. Besenyei L. R. Zsiros Z. Bozsó P. G. Ott 《Biologia Plantarum》2012,56(3):551-559
The leaf apoplast is a dynamic compartment in contact with plant pathogenic bacteria after infection. Among the very first
interaction events is the receptor-mediated perception of bacterial surface molecules such as flagellin or other conserved
microbe-associated molecular patterns (MAMPs). Apoplast proteins likely play a role in basal resistance (BR) or pattern-triggered
immunity (PTI). Here, a proteomic approach was carried out on water soluble — potentially the most mobile — apoplast proteins
from flagellin-treated tobacco (Nicotiana tabacum) leaves. As the quickness of BR/PTI seems crucial for its efficacy, samples were taken as early as 2.5 and 7 h post inoculation.
Proteins were separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and identified by liquid chromatography
tandem mass spectrometry (LC-MS/MS). Forty-nine different proteins from 28 protein spots changed in their density compared
to the water-inoculated control. Eleven protein spots appeared de novo in response to EBR induction. There are glycohydrolases and redox-active proteins besides pathogenesis-related proteins among
them, predicting plant cell wall structural modifications and more direct antimicrobial effectors as earliest changes related
to BR/PTI. 相似文献
17.
Aspartic acids 96 and 85 play a central role in the function of bacteriorhodopsin as a proton pump. 总被引:41,自引:9,他引:32
下载免费PDF全文
![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A spectroscopic and functional analysis of two point-mutated bacteriorhodopsins (BRs) from phototrophic negative halobacterial strains is reported. Bacteriorhodopsin from strain 384 contains a glutamic acid instead of an aspartic acid at position 85 and BR from strain 326 contains asparagine instead of aspartic acid at position 96. Compared to wild-type BR, the M formation in BR Asp85---Glu is accwelerated approximately 10-fold, whereas the M decay in BR Asp96---Asn is slowed down approximately 50-fold at pH6. Purple membrane sheets containing the mutated BRs were oriented and immobilized in polyacrylamide gels or adsorbed to planar lipid films. The measured kinetics of the photocurrents under various conditions agree with the observed photocycle kinetics. The ineffectivity of BR Asp85---Glu resides in the dominance of an inactive species absorbing maximally at approximately 610 nm, while BR Asp96---Asn is ineffective due to its slow photocycle. These experimental results suggest that aspartic acid 96 plays a crucial role for the reprotonation of the Schiff base. Both residues are essential for an effective proton pump. 相似文献
18.
By means of high-intensity 532 nm laser pulses, a photochemical conversion of the initial B(570) state of bacteriorhodopsin (BR) to a stable photoproduct absorbing maximally at approximately 620 nm in BR suspensions and at approximately 610 nm in BR films is induced. This state, which we named F(620), is photochemically further converted to a group of three products with maximal absorptions in the wavelength range from 340 nm to 380 nm, which show identical spectral properties to the so-called P(360) state reported in the literature. The photoconversion from B(570) to F(620) is most likely a resonant two-photon absorption induced step. The formation of F(620) and P(360) leads to a distinguished photo-induced permanent optical anisotropy in BR films. The spectral dependence of the photo-induced anisotropy and the anisotropy orientations at the educt (B(570)) and product (F(620)) wavelengths are strong indicators that F(620) is formed in a direct photochemical step from B(570). The chemical nature of the P(360) products probably is that of a retro-retinal containing BR, but the structural characteristics of the F(620) state are still unclear. The photo-induced permanent anisotropy induced by short laser pulses in BR films helps to better understand the photochemical pathways related to this transition, and it is interesting in view of potential applications as this feature is the molecular basis for permanent optical data storage using BR films. 相似文献
19.
Energy management that generates terrain following versus apex-preserving hopping in man and machine
While hopping, 12 subjects experienced a sudden step down of 5 or 10 cm. Results revealed that the hopping style was “terrain
following”. It means that the subjects pursued to keep the distance between maximum hopping height (apex) and ground profile
constant. The spring-loaded inverse pendulum (SLIP) model, however, which is currently considered as template for stable legged
locomotion would predict apex-preserving hopping, by which the absolute maximal hopping height is kept constant regardless
of changes of the ground level. To get more insight into the physics of hopping, we outlined two concepts of energy management:
“constant energy supply”, by which in each bounce—regardless of perturbations—the same amount of mechanical energy is injected,
and “lost energy supply”, by which the mechanical energy that is going to be dissipated in the current cycle is assessed and
replenished. When tested by simulations and on a robot testbed capable of hopping, constant energy supply generated stable
and robust terrain following hopping, whereas lost energy supply led to something like apex-preserving hopping, which, however,
lacks stability as well as robustness. Comparing simulated and machine hopping with human hopping suggests that constant energy
supply has a good chance to be used by humans to generate hopping. 相似文献
20.
Leen Vandepitte Francisco Hernandez Simon Claus Bart Vanhoorne Nathalie De Hauwere Klaas Deneudt Ward Appeltans Jan Mees 《Hydrobiologia》2011,667(1):1-14
The European Ocean Biogeographic Information System—EurOBIS—is an integrated data system developed by the Flanders Marine
Institute (VLIZ) for the EU Network of Excellence “Marine Biodiversity and Ecosystem Functioning” (MarBEF) in 2004. Its principle
aims are to centralise the largely scattered biogeographical data on marine species collected by European institutions and
to make these quality-controlled data freely available and easily accessible. It is in essence a distributed system in which
individual datasets go through a series of quality control procedures before they are integrated into one large consolidated
database. EurOBIS is freely available online at , where marine biogeographical data—with a focus on taxonomy, temporal and spatial distribution—can be consulted and downloaded
for analyses. Over the last 6 years, EurOBIS has collected 228 datasets contributed by more than 75 institutes, representing
over 13.6 million distribution records of which almost 12.5 million records are species level identifications. It is now the
largest online searchable public source of European marine biological data, holding biogeographical information on 26,801
species and 9,221 genera. EurOBIS acts as the European node of OBIS, the Ocean Biogeographic Information System of the Census
of Marine Life (CoML). EurOBIS shares its data with OBIS, which in its turn shares its content with the Global Biodiversity
Information Facility (GBIF). This article describes the status of the European Ocean Biogeographic Information System, identifies
data gaps, possible applications, uses and limitations. It also formulates a strategy for the growth and improvement of the
system and wants to appeal for more contributions. 相似文献