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1.
Christiane Wloczyk Achim Kröger Thomas Göbel Gabriele Holdt Ralf Steudel 《Archives of microbiology》1989,152(6):600-605
Wolinella succinogenes grown on formate and elemental sulphur was found to use the polysulphide derivatives 2,2-tetrathiobispropionate (R2S4) or pentathionate (S5O
6
=
) as acceptors for formate oxidation. The specific activities of formate oxidation with these acceptors were similar to those with elemental sulphur. The main reaction products of R2S4 reduction were 2,2-dithiobispropionate (R2S2) and sulphide. Pentathionate was converted to thiosulphate and some elemental sulphur. The electrochemical proton potential
across the cytoplasmic membrane of the bacterium was measured in the steady state of electron transport from formate to R2S4. The electrical proportion () of the
determined through the distribution of labeled tetraphenylphosphonium cation was obtained as 0.17 Volt. The was zero, when a protonophore was present. The pH-difference across the membrane was negligible. Thus the
generated by sulphur respiration is close to that measured earlier with fumarate as the terminal acceptor of electron transport.Abbreviations DMO
5,5-dimethyloxazolidine-2,4-dione
- R2Sn (n=2–5)
2,2-polythiobispropionate
- TTFB
4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazol
- TPP
tetraphenylphosphonium cation 相似文献
2.
In Wolinella succinogenes ATP synthesis and consequently bacterial growth can be driven by the reduction of either nitrate (E0=+0.42 V), nitrite (E0=+0.36 V), fumarate (E0=+0.03 V) or sulphur (E0=-0.27 V) with formate as the electron donor. Bacteria growing in the presence of nitrate and fumarate were found to reduce both acceptors simultaneously, while the reduction of both nitrate and fumarate is blocked during growth with sulphur. These observations were paralleled by the presence and absence of the corresponding bacterial reductase activities. Using a specific antiserum, fumarate reductase was shown to be present in bacteria grown with fumarate and nitrate, and to be nearly absent from bacteria grown in the presence of sulphur. The contents of polysulphide reductase, too, corresponded to the enzyme activities found in the bacteria. This suggests that the activities of anaerobic respiration are regulated at the biosynthetic level in W. succinogenes. Thus nitrate and fumarate reduction are repressed by the most electronegative acceptor of anacrobic respiration, sulphur. By contrast, in Escherichia coli a similar effect is exerted by the most electropositive acceptor, O2. W. succinogenes also differs from E. coli in that fumarate reductase is not repressed by nitrate.Abbreviations BV
benzyl viologen
- DMN
2,3-dimethyl-1,4-naphthoquinone
- DMSO
dimethylsulfoxide
- TMAO
trimethylamine-N-oxide 相似文献
3.
Wolinella succinogenes can grow at the expense of sulphur reduction by formate. The enzymes involved in the catalysis of this catabolic reaction have been investigated. From the results the following conclusions are drawn: 1. The enzyme isolated as a sulphide dehydrogenase from the cytoplasmic membrane of W. succinogenes is the functional sulphur reductase that operates in the electron transport from formate to sulphur. 2. The enzyme (Mr 200,000) consists essentially of one type of subunit with the Mr 85,000 and contains equal amounts of free iron and sulphide (120 mol/g protein), but no heme. It represents the first functional sulphur reductase ever isolated. 3. The electron transport chain catalyzing sulphur reduction by formate consists merely of formate dehydrogenase and sulphur reductase. A lipophilic quinone which mediates the transfer of electrons between enzymes in other chains, is apparently not involved. This is the first known example of a phosphorylative electron transport chain that operates without a quinone. 4. The same formate dehydrogenase appears to operate in the electron transport both with sulphur and with fumarate as the terminal electron acceptor in W. succinogenes.Abbreviations DMN
2,3-Dimethyl-1,4-naphthoquinone
- DTT
dithiothreitol
- MK
menaquinone (vitamin K2)
- PMSF
phenylmethane sulfonylfluoride
- Tricine
N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]-glycine
- Tea
triethanolamine
- Hepes
4-(2-hydroxyethyl)-1-piperazineethane sulfonate
Dedicated to Professor F. Schneider (Philipps-Universität Marburg) on the occasion of his 60th birthday 相似文献
4.
Bernardina L. M. Van Kuijk Elvire Schlösser Alfons J. M. Stams 《Archives of microbiology》1998,169(4):346-352
The growth of the syntrophic propionate-oxidizing bacterium strain MPOB in pure culture by fumarate disproportionation into
carbon dioxide and succinate and by fumarate reduction with propionate, formate or hydrogen as electron donor was studied.
The highest growth yield, 12.2 g dry cells/mol fumarate, was observed for growth by fumarate disproportionation. In the presence
of hydrogen, formate or propionate, the growth yield was more than twice as low: 4.8, 4.6, and 5.2 g dry cells/mol fumarate,
respectively. The location of enzymes that are involved in the electron transport chain during fumarate reduction in strain
MPOB was analyzed. Fumarate reductase, succinate dehydrogenase, and ATPase were membrane-bound, while formate dehydrogenase
and hydrogenase were loosely attached to the periplasmic side of the membrane. The cells contained cytochrome c, cytochrome b, menaquinone-6 and menaquinone-7 as possible electron carriers. Fumarate reduction with hydrogen in membranes of strain MPOB
was inhibited by 2-(heptyl)-4-hydroxyquinoline-N-oxide (HOQNO). This inhibition, together with the activity of fumarate reductase with reduced 2,3-dimethyl-1,4-naphtoquinone
(DMNH2) and the observation that cytochrome b of strain MPOB was oxidized by fumarate, suggested that menequinone and cytochrome b are involved in the electron transport during fumarate reduction in strain MPOB. The growth yields of fumarate reduction
with hydrogen or formate as electron donor were similar to the growth yield of Wolinella succinogenes. Therefore, it can be assumed that strain MPOB gains the same amount of ATP from fumarate reduction as W. succinogenes, i.e. 0.7 mol ATP/mol fumarate. This value supports the hypothesis that syntrophic propionate-oxidizing bacteria have to
invest two-thirds of an ATP via reversed electron transport in the succinate oxidation step during the oxidation of propionate.
The same electron transport chain that is involved in fumarate reduction may operate in the reversed direction to drive the
energetically unfavourable oxidation of succinate during syntrophic propionate oxidation since (1) cytochrome b was reduced by succinate and (2) succinate oxidation was similarly inhibited by HOQNO as fumarate reduction.
Received: 18 March 1997 / Accepted: 10 November 1997 相似文献
5.
Henrik Laasch 《Planta》1989,178(4):553-560
A series of tertiary amines was investigated for effects on the transmembrane proton potential difference (
H), on photophosphorylation and on electron-flux control related to the intrathylakoid proton potential (
HI), using isolated chloroplasts ofSpinacia oleracea L. As indicated by 9-aminoacridine fluorescence and [14C]methylamine uptake, all amines studied inhibited a build-up of
H and, in parallel, ATP synthesis. Even when
H was low, strong
H1-dependent electron-flux control was observed under the influence of tertiary amines. The strength of flux control in the presence of low
H and the effectiveness of inhibition of ATP synthesis linearly increased with the lipophilicity of the amines. The most effective of the amines tested caused 50% inhibition of ATP synthesis at a concentration of 6 M, which is about 1000-fold lower than the concentration required for inhibition by methylamine. The data presented indicate the existence of two proton domains in the thylakoid vesicles, one of them feeding the ATP-synthase, the other the sites of pH-dependent electron-flux control. It is concluded that tertiary amines develop their action in a lipophilic domain of the thylakoid membrane, in the vicinity of the ATP-synthase complex. A mechanism for selective uncoupling and for the maintenance of
HI-dependent electron flux control in the presence of low
H is discussed.Abbreviations and symbols
coefficient for pH-dependent electron flux control
- 9-AA
9-aminoacridine
- Chl
chlorophyll
- I50
amine concentration producing 50% inhibition of ATP-synthesis
- Je
flux of photosynthetic electron transport
-
k
H
apparent rate constant for proton efflux
-
H1
proton potential in the thylakoid lumen
-
H1
transthylakoid proton potential difference
-
p
partition coefficient
-
q
AA
coefficient for 9-aminoacridine fluorescence quenching
- PS
photosystem
- Q
quantum flux of photosynthetically active light
Dedicated to Professor Wilhelm Simonis, on the occasion of his 80th birthday 相似文献
6.
Some of the photosynthetic reactions were measured under aerobic and anaerobic conditions in intact cells of an aerobic photosynthetic bacterium Erythrobacter species strain OCh 114 (ATCC No. 33942). In intact cells, the flash-light induced oxidation of cytochrome c-551, the continuous light-induced oxidation of reaction center bacteriochlorophyll and the continuous light-induced pH change (
) of the suspension decreased on aerobic-anaerobic transition and almost disappeared under anaerobic conditions. These photosynthetic reactions reappeared when the suspension was aerated again. These phenomena were reconciled with the fact that Erythrobacter sp. cannot grow anaerobically even in the light. The incompetence of photoanaerobic growth of this bacterium was explained by the reduction of the primary electron acceptor (QI) before illumination, resulting partly from the relatively high midpoint potential of QI of this bacterium.Abbreviations QI
Primary electron acceptor
- Eh
ambient redox potential
- Em
midpoint redox potential 相似文献
7.
V. P. Skulachev 《Journal of bioenergetics and biomembranes》1989,21(6):635-647
The progress of bioenergetic studies on the role of Na+ in bacteria is reviewed. Experiments performed over the past decade on several bacterial species of quite different taxonomic positions show that Na+ can, under certain conditions, substitute for H+ as the coupling ion. Various primary Na+ pumps (
generators) are described, i.e., Na+-motive decarboxylases, NADH-quinone reductase, terminal oxidase, and ATPase. The
formed is shown to be consumed by Na+ driven ATP-synthase, Na+ flagellar motor, numerous Na+, solute symporters, and the methanogenesis-linked reverse electron transfer system. InVibrio alginolyticus, it was found that
, generated by NADH-quinone reductase, can be utilized to support all three types of membrane-linked work, i.e., chemical (ATP synthesis), osmotic (Na+, solute symports), and mechanical (rotation of the flagellum). InPropionigenum modestum, circulation of Na+ proved to be the only mechanism of energy coupling. In other species studied, the Na+ cycle seems to coexist with the H+ cycle. For instance, inV. alginolyticus the initial and terminal steps of the respiratory chain are Na+ - and H+-motive, respectively, whereas ATP hydrolysis is competent in the uphill transfer of Na+ as well as of H+. In the alkalo- and halotolerantBacillus FTU, there are H+ - and Na+-motive terminal oxidases. Sometimes, the Na+-translocating enzyme strongly differs from its H+-translocating homolog. So, the Na+-motive and H+-motive NADH-quinone reductases are composed of different subunits and prosthetic groups. The H+-motive and Na+-motive terminal oxidases differ in that the former is ofaa
3-type and sensitive to micromolar cyanide whereas the latter is of another type and sensitive to millimolar cyanide. At the same time, both Na+ and H+ can be translocated by one and the sameP. modestum ATPase which is of the F0F1-type and sensitive to DCCD. The sodium cycle, i.e., a system composed of primary
generator(s) and
consumer(s), is already described in many species of marine aerobic and anaerobic eubacteria and archaebacteria belonging to the following genera:Vibrio, Bacillus, Alcaligenes, Alteromonas, Salmonella, Klebsiella, Propionigenum, Clostridium, Veilonella, Acidaminococcus, Streptococcus, Peptococcus, Exiguobacterium, Fusobacterium, Methanobacterium, Methanococcus, Methanosarcin, etc. Thus, the sodium world seems to occupy a rather extensive area in the biosphere. 相似文献
8.
Shih-fang Fan M. M. Dewey B. Gaylinn B. Chu 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(6):508-512
Summary In dynamic light scattering, measurements of the intensity-intensity time correlation function from a suspension of rod-like particles of length L could reveal dynamical information related to translational and internal motions of those particles. For a suspension of thick filaments isolated from the myosin-regulated, striated muscles of Limulus at KL>1 (where K is the scattering vector), the average characteristic linewidth (
) increased with the addition of Ca2+ or with the depletion of ATP. The increase in the
with the addition of Ca2+ could be due to the presence of energy-requiring, high-frequency motions of the crossbridges activated by Ca2+. The increase in
which occurred with the depletion of ATP was assumed to be mainly due to the thermal motions of the crossbridges after they had moved radially away from the filament backbone. The percentage increase in
following the addition of Ca2+ was found to be seasonal, i.e., values of
obtained from thick filaments isolated between the middle of June and the middle of September were smaller than those obtained during the rest of the year. The effect of temperature on the percentage increase in
was also different. The increase showed a maximum at about 35°C during the summer and at about 25°C at other times. However, the percentage increase in
developed under ATP-depleted conditions showed no temperature-related maximum. The number of bound Ca2+ per myosin molecule was 1 during the summer and 2 at other times.Abbreviations DLS
dynamic light scattering
- L
length
- K
scattering vector
- SDS-PAGE
sodium dodecyl sulfate polyacrylamide gel electrophoresis
-
average characteristic line width
Deceased 相似文献
9.
Vibrio succinogenes which gains all the ATP by anaerobic electron transport phosphorylation, was grown in continuous culture on a defined medium with formate and fumarate as sole energy sources. The growth yield at infinite dilution rate (Y
max) was obtained by extrapolation from the growth yields measured at various dilution rates. With formate as the growth limiting substrate, Y
max was found as 14 g dry cells/mol formate. Under these conditions growth was limited by the rate of energy supply, because formate is used only as a catabolic substrate (Bronder et al. 1982). The Y
ATP
max
calculated from the ATP requirement for cell synthesis was 18 g dry cells/mol ATP. This gives an ATP/2e ratio of 0.8. The ATP/2e ratio in vitro had been measured as 1 (Kröger and Winkler 1981). It is concluded that growing V. succinogenes gain at least 80% the stoichiometrically possible amount of ATP, when growth is limited by energy supply. 相似文献
10.
Transport of H+, K+, Na+ and Ca++ in Streptococcus 总被引:6,自引:0,他引:6
D. L. Heefner 《Molecular and cellular biochemistry》1982,44(2):81-106
Summary The streptococci differ from other bacteria in that cation translocations (with the possible exception of one of the K+ uptake systems) occur by primary transport systems, i.e., by cation pumps which use directly the free energy released during hydrolysis of chemical bonds to power transport. Transport systems in other bacteria, especially for Na+ and Ca++, are often secondary, using the free energy of another ion gradient to drive cation transport. In streptococci H+ efflux occurs via the F1F0-ATPase. This enzyme is composed of eight distinct subunits. Three of the subunits are embedded in the membrane and form a H+ channel; this is called the F0 portion of the enzyme. The other five subunits form the catalytic part of the enzyme, called F1, which faces the cytoplasm and can easily be stripped from the membrane. Physiologically, this enzyme functions as a H+-ATPase, pumping protons out of the cell to form an electrochemical proton gradient,
. The F1F0-ATPase, however, is fully reversible and if supplied with Pi, ADP and a
+ of sufficient magnitude (ca –200 mv) catalyzes the synthesis of ATP.
Streptococcus faecalis can accumulate K+ and establish a gradient of 50 000:1 (in>out) under some conditions. Uptake occurs by two transport systems. The dominant, constitutive system requires both an electrochemical proton gradient and ATP to operate. The minor, inducible K+ transport system, which has many similarities to the K+-ATPase of the Kdp transport system found in Escherichia coli, requires only ATP to power K+ uptake.Sodium extrusion occurs by a Na+/H+-ATPase. Exchange is electroneutral and there is no requirement for a
. The possibility that the Na+/H+-ATPase may consist of two parts, a catalytic subunit and a Na+/H+ antiport subunit, is suggested by the finding that damage to the Na+ transport system either through mutation or protease action leads to the appearance of
-requiring Na+/H+ antiporter activity.Ca++ like Na+ is extruded from metabolizing, intact cells. Transport requires no
but does require ATP. Reconstitution of Ca++ transport activity with accompanying Ca++-stimulated ATPase activity into proteoliposomes suggests that Ca++ is transported by a Ca++-translocating ATPase.Where respiring organelles and bacteria use secondary
transport systems the streptococci have developed cation pumps. The streptococci, which are predominantly glycolyzing bacteria, generate a
much inferior to that of respiring organisms and organelles. The cation pumps may have developed simply in response to an inadequate
.Abbreviations
electrochemical potential of protons
-
membrane potential
- pH
pH gradient
- p
proton-motive force
- DCCD
N,Na1-dicyclohexlcarbodiimide
- TCS
tetrachlorosalicylanilide
- FCCP
carbonylcyanide-p-trifluoromethylphenylhydrazone
- CCCP
carbonylcyanie-m-chlorophenylhydrazone
- TPMP+
triphenylmethyl phosphonium ion
- DDA+
dibenzyldimethylammonium ion
- Hepes
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- EGTA
ethyleneglycol-bis (amino-ethyl-ether)-N,N-tetraacetic acid 相似文献
11.
The oxidation of succinate with elemental sulphur in Desulfuromonas acetoxidans was investigated using a membrane preparation of this bacterium. The following results were obtained:
- The preparation catalyzed the oxidation of succinate with sulphur and NAD. These reactions were dependent on ATP and were abolished by the presence of protonophores or dicyclohexylcarbodiimide (DCCD).
- The membrane preparation also catalyzed the reduction of fumarate with H2S or with NADH. These activities were not dependent on ATP and were not affected by protonophores or DCCD.
- By extraction-reincorporation experiments it could be shown that menaquinone is involved in electron transport between H2S and fumarate and between NADH and fumarate.
- The membrane fraction catalyzed the reduction of the water-soluble menaquinone-analogue dimethylnaphthoquinone (DMN) by succinate, H2S, or NADH, and the oxidation of DMNH2 by fumarate. These activities were not dependent on the presence of menaquinone and were not influenced by ATP.
- The activities involving succinate oxidation or fumarate reduction were similarly sensitive to 2(n-nonyl)-4-hydroxyquinoline-N-oxide, while H2S and NADH oxidation by DMN were not affected by the inhibitor.
12.
Respiratory chain phosphorylation has been investigated in the methylotrophic bacterium Methylophilus methylotrophus following the addition of oxidisable substrates to aerobic, whole cell suspensions. Initial-rate experiments showed that ATP synthesis occurred at the overall expense of AMP and inorganic phosphate via the sequential action of the ATP phosphohydrolase and adenylate kinase; some of the nascent ATP was rapidly used to synthesis nonadenine nucleoside triphosphates. After being corrected for ATP turnover, Pi/O quotients of 0.46 to 0.54, 0.77 and 1.37 nmol/ng-atom O were obtained for the oxidation of methanol dehydrogenase-linked substrates (methanol, ethanol and acetaldehyde), duroquinol and formate (NAD+-linked) respectively. These values were proportional to the H+/O and/or K+/O quotients exhibited by these substrates, and yielded an average H+/ATP (H+/Pi) quotient of 4.2 ng-ion H+/nmol. Steady-state experiments showed that the extent of cellular energisation varied with the respiration rate but was always in the order methanol > duroquinol > acetaldehyde, thus indicating that under these longer-term conditions methanol was completely oxidised to yield PQQH2 and 2NAD(P)H. These results are discussed in terms of the various reactions which lead to the generation or utilisation of the protonmotive force in this organism.Abbreviations FCCP
carbonylcyanide p-trifluoromethyxyphenyl-hydrazone
-
bulk phase, transmembrane electrochemical potential difference of protons (
)
- pH
bulk phase, transmembrane pH difference (pHin–pHout)
-
bulk phase, transmembrane electrical potential difference (in - out)
- [P]
concentration of anhydride phosphate bonds in adenine nucleotides (2[ATP]+[ADP])
- FPLC
fast protein liquid chromatography
- PQQ
pyrroloquinoline quinone
- Gp
phosphorylation potential 相似文献
13.
Tightly coupled membranes of Paracoccus denitrificans catalyze oxidative phosphorylation but are incapable of ATP hydrolysis. The conditions for observation and registration of the venturicidin-sensitive ATPase activity of subbacterial particles derived from this organism are described. The ATP hydrolytic activity does not appear after prolonged incubation in the presence of pyruvate kinase and phosphoenol pyruvate (to remove ADP), EDTA (to remove Mg2+) and/or inorganic phosphate, whereas the activity dramatically increases after energization of the membranes. ATP hydrolysis by
activated ATPase is coupled with electric potential formation. Inorganic phosphate prevents and azide promotes a decline of the enzyme activity during ATP hydrolysis. The addition of uncouplers results in rapid and complete inactivation of ATPase. The
dependent ATPase activity increases upon dilution of the membranes. The results are discussed as evidence for the presence of distinct ATP-synthase and ATP-hydrolase states of FoF1 complex in the coupling membranes (Vinogradov, A. D. (1999) Biochemistry (Moscow), 64, 1219-1229). The proposal is made that part of the free energy released from oxidoreduction in the respiratory chain is used to maintain active conformation of the energy-transducing proteins. 相似文献
14.
D. B. Sattelle K. H. Langley A. L. Obaid B. M. Salzberg 《European biophysics journal : EBJ》1987,15(2):71-76
Quasi-elastic laser light scattering has been used to investigate the size and dispersity of synaptosomes and synaptic vesicles isolated from optic lobes of the squid Loligo pealei. Synaptosomal fractions were highly polydisperse (
) and the mean diameter (
) ranged from 0.5–2.0 m. Size distribution histograms yielded two major components — smaller particles (
) and a larger group of particles (
). The heterogeneity of the synaptosomal particles detected in solution is in agreement with published data obtained using electron microscopy. Purified synaptic vesicle fractions also yielded complex particle size distribution data. A component with a mean diameter in the range 150–250 nm was detected, though a smaller particle (
) dominated the scattering signal. This smaller particle closely resembles in size the electron lucent vesicles seen in the majority of squid optic lobe nerve terminals when examined by electron microscopy. Osmotically-induced shirnkage and swelling of the synptosomes was detected. Depolarization by veratridine (1.0×10–4
M) did not result in a detectable change in the size of synaptosomal particles. 相似文献
15.
Summary The rate of inorganic carbon uptake and its steadystate accumulation ratio (intracellular/extracellular concentration) was determined in the cyanobacteriumAnabaena variabilis as a function of extracellular pH. The free energy of protons (
) across the plasmalemma was calculated from determinations of membrane potential, and intracellular pH, as a function of the extracellular pH. While inward proton motive force decreased with increasing extracellular pH from 6.5 to 9.5, rate of HCO
3
–
influx and its accumulation ration increased. The latter is several times larger than would be expected should HCO
3
–
influx be driven by
. It is concluded that HCO
3
–
transport in cyanobacteria is not driven by the proton motive force. 相似文献
16.
Yu. F. Krupyanskii D. Bade I. V. Sharkevich N. Ya. Uspenskaya A. A. Kononenko I. P. Suzdalev F. Parak V. I. Goldanskii R. L. Mössbauer A. B. Rubin 《European biophysics journal : EBJ》1985,12(2):107-114
Chromatophores from Ectothiorhodospira Shaposhnikovii in solvents of different viscosity were investigated by RSMR experiments in the temperature range between 112 K and room temperature. Additional RSMR-experiments were done on solvents only. The mobility of the molecules and within the molecules is the given by the Debye-Waller factor which yields the meansquare displacement,
, averaged over the atoms in the system. The mobility of the atoms of the chromatophores roughly follows the mobility of the atoms of the solvents. At low temperatures the mobility of the chromatophores remains slightly larger than the mobility of the frozen solvent. At room temperature, however,
of the chromatophores remains significantly smaller.Chromatophores in a glycerol-water mixture (0.001 M Tris-HCl buffer) and in water (0.05 M Tris-HCl buffer) show a different dynamic behaviour. A region with enhanced mobility near T=180 K was indicated for the chromatophores in the glycerolwater mixture.A correlation has been suggested between the rate of electron transfer from the primary to the secondary quinone and the increase of the conformational mobility of the chromatophores in glycerol-water mixture.Abbreviations Mb
Myoglobin
- Met-Mb
Metmyoglobin 相似文献
17.
The effect of short-term fasting and a single meal on protein synthesis and oxygen consumption in cod,Gadus morhua 总被引:2,自引:0,他引:2
A. R. Lyndon D. F. Houlihan S. J. Hall 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(3):209-215
Summary Rates of protein synthesis and oxygen consumption (
O2) in cod were compared in both fasted and refed animals. During a 14-day fast both protein synthesis and respiration rates fell to stable values after 6 days. When a meal of whole sandeel at 6% body weight was fed to fish fasted for 6 days, protein synthesis and (
O2) increased to a maximum at between 12 and 18 h after feeding. Peak (
O2) was about twice the pre-feeding values, while whole animal protein synthesis increased four-fold. There were differences between tissues in the timing of maximum protein synthesis; the liver and stomach responded faster than the remainder of the body. Maximum protein synthesis rates in the liver and stomach occurred at 6 h after feeding, at which time their calculated contribution to total (
O2) was 11%. Similar calculations suggested that the integrated increment in whole animal protein synthesis contributed between 23% and 44% of the post-prandial increase in (
O2). It was concluded that protein synthesis is an important contributor to increased (
O2) after feeding in cod.Abbreviations
A
s
absolute rate of protein synthesis
- ASDA
apparent specific dynamic action
- ATP
adenosine triphosphate
-
k
s
fractional rate of protein synthesis
-
k
s/RNA
amount of protein synthesized per unit RNA
- (
O2)
oxygen consumption
- PCA
perchloric acid
- RNA
ribonucleic acid 相似文献
18.
P. A. Dibrov R. L. Lazarova V. P. Skulachev M. L. Verkhovskaya 《Journal of bioenergetics and biomembranes》1989,21(3):347-357
Addition of Na+ to the K+-loadedVibrio alginolyticus cells, creating a 250-fold Na+ gradient, is shown to induce a transient increase in the intracellular ATP concentration, which is abolished by the Na+/H+ antiporter, monensin. The pNa-supported ATP synthesis requires an additional driving force supplied by endogenous respiration or, alternatively, by a K+ gradient (high [K+] inside). In the former case, ATP formation is resistant to the protonophorous uncoupler. Dicyclohexylcarbodiimide and diethylstilbestrol, but not vanadate, completely inhibit Na+ pulse-induced ATP formation. The data agree with the assumption that Na+-ATP-synthase is involved in oxidative phosphorylation inV. alginolyticus. Interrelation of H+ and Na+ cycles in bacteria is discussed.Abbreviations
and
electrochemical gradients of H+ and Na+, respectively
-
transmembrane electric potential difference
- pH, pNa, and pK
concentration gradients of H+, Na+, and K+, respectively
- CCCP
carbonyl cyanidem-chlorophenylhydrazone
- DCCD
N,N-dicyclohexylcarbodiimide
- DES
diesthylstilbestrol
- HQNO
2-heptyl-4-hydroxyquinolineN-oxide
- Tricine
N[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine 相似文献
19.
Stephen C. Wood Kjell Johansen Mogens L. Glass G. M. O. Maloiy 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,127(4):331-336
Summary Oxygen consumption
was measured at rest and during spontaneous activity at body temperatures of 25 and 35°C in 14 fasting Savanna monitor lizards,Varanus exanthematicus ranging in weight from 172 to 7500 g. The allometric relationship between metabolic rate at 25°C and body weight (W) is given by:
(ml O2 STPD·g–1·hr–1)=0.88W
–0.43 (Fig. 2). Although statistical comparisons are equivocal, this intraspecific size dependence exceeds that reported for interspecific comparisons among reptiles and other vertebrate groups (Fig 3). A reproducible diurnal pattern of activity was observed in undisturbed animals with minimum values of
between 2400 and 0800 h (Fig. 1). Spontaneous activity and
generally reached peak values between 1200 and 2000 hrs. The average ratio of active aerobic metabolic rate (AMR) to minimum (standard) aerobic metabolic rate (SMR) was 8.2. This voluntary AMR/SMR inVaranus exceeds the AMR/SMR for most reptiles stimulated to exhaustion. The high aerobic capacity is consistent with other evidence for efficient exchange and transport of respiratory gases inV. exanthematicus; e.g., low or absent intracardiac shunt flow resulting in high arterial saturation and low ventilation
and perfusion
requirements. 相似文献
20.
Wytske de Vries H. G. D. Niekus Marian Boellaard A. H. Stouthamer 《Archives of microbiology》1980,124(2-3):221-227
Campylobacter sputorum subspecies bubulus was grown in continuous culture with excess of l-lactate or formate, and growth-limiting amounts of oxygen, fumarate, nitrate or nitrite. l-Lactate was oxidized to acetate, fumarate was reduced to succinate, and nitrate and nitrite were reduced to ammonia. The Y
lactate values (g dry weight bacteria/g mol lactate) for the respective hydrogen acceptors were much higher than the Y
formate values. Steady state cultures on formate and nitrite could only be obtained at a low dilution rate and low nitrite concentrations in the growth medium. In H+/2e measurements with lactate-grown cells proton ejections were observed with lactate or pyruvate as a hydrogen donor, and oxygen or hydrogen peroxide as a hydrogen acceptor. Proton ejection was also observed with pyruvate and nitrate. Proton ejection did not occur with lactate and nitrate, neither with lactate or pyruvate and fumarate or nitrite. With formate as a hydrogen donor acidification occurred with all hydrogen acceptors mentioned. It has been concluded that during growth on lactate and fumarate or nitrite substrate level phosphorylation at acetate formation is the sole ATP-generating system. Growth on formate and fumarate or nitrite is explained by a proton gradient generated as a result of oxidation of formate at the periplasmic side of the cytoplasmic membrane. With oxygen and nitrate additional ATP is formed by electron transport-linked phosphorylation. The low molar growth yields with formate are explained by the observation that formate-grown cells had a great permeability to protons.Abbreviations H+/2e value
number of protons ejected per electron pair transported in the respiratory system
- P/2e value
mol of ATP formed per electron pair transported in the respiratory system
- CCCP
carbonyl cyanide m-chlorophenyl-hydrazone 相似文献