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1.
Formaldehyde accumulation ratios ([14CH2O]i/[14CH2O]o) as high as 12-fold were measured in anaerobic, CH3OH-energized, whole cell suspensions of the ribulose monophosphate (RuMP)-type methylotrophic strain T15. Uptake kinetics were extremely rapid, enabling the attainment of equilibrium in only 10–30 s. Transport appears to be energy-dependent and associated with the protonmotive force (pmf). Anaerobic incubation with 5 M carbonyl p-(trifluoromethoxy)-phenylhydrazone (FCCP) led to 70%–90% reduction of the accumulation ratio. Though not as pronounced, diminished uptake was also observed in the presence of 140 M nigericin, 161 M valinomycin and 90 mM KSCN, commensurate with their effects on pmf. Accumulation of CH2O as a function of external pH followed a trend more similar to that of pmf than either pH or . Preventing energization by incubation with 100 M N,N-dicyclohexylcarbodiimide (DCCD) led to nearly 80% inhibition of CH2O transport. Over short time periods it was possible to chase accumulated 14CH2O from previously loaded cells by collapsing pmf; however, this technique also indicated that significant 14CH2O incorporation began to occur within 3 min.Abbreviations FCCP
Carbonyl cyanide p-(trifluoromethyoxy)-phenylhydrazone
- DCCD
N,N-dicyclohexylcarbodiimide
- RuMP
ribulose monophosphate
- TPP+
tetra[U-14C]phenylphosphonium
- pmf
protonmotive force 相似文献
2.
O. P. Rajora J. D. Mahon 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,89(2-3):206-210
Restriction fragment analysis was used to examine the inheritance of lentil mitochondrial DNA (mtDNA) in F1 and F5 progeny from intrasubspecific (Lens culinaris ssp. culinaris) crosses and in F1 progeny from intersubspecific (Lens culinaris ssp. orientalis x L. culinaris ssp. culinaris) crosses. Southern blots of digested parental and progeny DNA were hybridized to heterologous maize mtDNA probes specific to coxI and atp6 genes. Two restriction fragment polymorphisms separated L.c. ssp. culinaris Laird and Eston from L.c. ssp. culinaris ILL5588, and one restriction fragment polymorphism distinguished L.c. ssp. culinaris Laird and Eston from L.c. ssp. orientalis LO4. Twelve of 13 f1 progeny and all F5 progeny from the intrasubspecific crosses, and all F1 progeny from intersubspecific crosses had only maternal mtDNA restriction fragments. One f1 plant from an Eston x ILL5588 cross inherited mtDNA fragments from both parents. Nuclear DNA inheritance was biparental in all F1 progeny.NRCC No. 38451 相似文献
3.
Summary We present ab initio calculations of the Fermi contact term and experimental correlations of six coupling constants, 3JH
N
H
, 1JC
H
, 2JCH
, 1JC
N, 2JC
N and 1JCN, in a peptide as functions of the backbone dihedral angles, and . Given estimates of experimental uncertainties, we find semiquantitative experimental correlations for 3JH
N
H
, 1JC
N and 2JC
N, qualitative correlations for 1JC
H
and 2JCH
, but no experimental correlations of practical utility for 1JCN, owing to its complex dependence on at least four dihedral angles. Errors in the estimation of dihedral angles from X-ray crystallographic data for proteins, which result from uncertainties in atom-to-atom distances, place substantial limitations on the quantitative reliability of coupling constant calculations fitted to such data. In the accompanying paper [Edison, A.S. et al., J. Biomol. NMR, 4, 543–551] we apply the results of the coupling constant calculations presented here to the estimation of and angles in staphylococcal nuclease from experimental coupling constants.Abbreviations AO
atomic orbital
- BPTI
basic pancreatic trypsin inhibitor (bovine)
- CI-2
chymotrypsin inhibitor 2
- E.COSY
exclusive correlation spectroscopy (Griesinger et al., 1986)
-
nJAB
single bond (n=1), geminal (n=2), or vicinal (n=3) coupling constant between nuclei A and B
- LCAO
linear combination of atomic orbitals
- NBO
natural bond orbital
- n
lone pair orbitals
-
bonding orbitals
- *
antibonding orbitals
-
dihedral angle or molecular orbital wave function; r2, correlation coefficient
- RHF
restricted Hartree-Fock; rmsd, root-mean-square deviation
- 3-21G and 6-31G*
molecular orbital basis set designations (Hehre et al., 1986) 相似文献
4.
D. J. Wolyn D. A. St. Clair J. DuBois J. C. Rosas R. H. Burris F. A. Bliss 《Plant and Soil》1991,138(2):303-311
The improvement of N2 fixation in legumes may lead to increased yields and reduced fertilizer requirement. Levels of N2 fixation were determined for three cultivars and nine progeny lines from two inbred backcross common bean (Phaseolus vulgaris L.) populations that were grown at Hancock, Wissconsin in 1984 and 1985 using 15N-depleted (NH4)2SO4. The high N2-fixing line Puebla 152 was the donor parent for both inbred backcross populations and the cultivars Porrillo Sintetico and Sanilac were the recurrent parents for populations 21 and 24, respectively. Total N yield, fixed N2 and % N derived from the atmosphere were determined for whole plants and plant parts at the R3 (50% bloom) and R9 (maturity) growth stages. Significant year-by-line interactions were found for N2 fixation traits among the population 21 lines and parents, but not for population 24 lines and their parents. Measures of N2 fixation at R3 were inadequate to predict N2 fixation at R9. Population 24 lines and parents differed for N2 fixation ability at R9, and fixed N2 was correlated with maturity. The recovery of an inbred backcross progeny line, 24-21, which matured earlier and fixed more N2 than the recurrent parent Sanilac indicated that N2 fixation was heritable and that favorable alleles, independent of maturity, were recovered from a late-maturing, high N2-fixing donor parent by utilizing the inbred backcross breeding method. Since most fixed N2 and non-fixed N (>80%) was found in the seeds at maturity, and most lines did not vary for the distribution of nitrogen throughout the plant, selection for improved remobilization of nitrogen to the seed to increase yield is impractical in this genetic material. The highest N2-fixing lines tended to have high and similar % Ndfa in all plant parts. 相似文献
5.
M. R. Brown C. D. Garland S. W. Jeffrey I. D. Jameson J. M. Leroi 《Journal of applied phycology》1993,5(3):285-296
Three species of microalgae commonly used in mariculture —Isochrysis sp. (clone T.ISO) Parke,Pavlova lutheri (Droop) Green andNannochloropsis oculata (Droop) Green — were grown in batch and semicontinuous modes to compare their biochemical composition and production rates.In batch mode, logarithmic-phase cultures of all species had high levels of protein (25.2 to 41.1) and low levels of carbohydrate (7.1 to 10.3) and lipid (8.8 to 14.9). At stationary phase, cultures ofIsochrysis sp. (clone T.ISO) andN. oculata contained significantly less protein (21.8 and 20.3, respectively), all species contained more carbohydrate (14.8 to 30.6), andP. lutheri contained more lipid (16.6). In semi-continuous mode, cultures maintained at late logarithmic-phase contained more carbohydrate,Isochrysis sp. (clone T.ISO) contained less protein, andP. lutheri more lipid than logarithmic-phase batch cultures of the same species. Neither growth phase nor harvest regime affected the amino acid composition of the microalgae significantly. However, the concentration of proline inN. oculata was higher in batch cultures in logarithmic phase (9.4), than in either semi-continuous cultures in logarithmic phase (5.8 to 7.9) or batch cultures in stationary phase (5.6 to 5.9).The production rates from batch and semi-continuous logarithmic-phase cultures were not significantly different for any of the species, and there were only minor differences in the production rates of the species (range 12.4 to 17.1 mg algae dry weight 1–1 d–1). The different culture and harvest regimes produced significant differences in the proportions of protein and carbohydrate in the microalgae. Which regime is chosen for culturing these microalgae as food will depend on the nutritional requirements of the animal species being fed. 相似文献
6.
Anti-Pr cold agglutinins (CAs) with the subspecificities anti-Pr1h,-Pr1d, -Pr2, -Pr3h, -Pr3d, -PrM and anti-Sa CAs recognize immunodominantN-acetylneuraminic acid (NeuN Ac) groups of tetra and/or trisaccharides (O-glycans) of glycophorin. These O-glycans are sialylated in 2,3- and/or 2,6-linkages. Sa and most Pr antigens have been inactivated by 2,3-specific sialidases. Antigenicity was reconstituted on desialylated glycophorin by 2,3-specific Gal1,3GalN Ac-sialyltransferase indicating that 2,3-linked NeuN Ac groups are the immunodominant components of Sa and most Pr antigens. Some Pr antigens were resistant to 2,3-specific sialidase and were not reconstituted by 2,3-specific Gal1,3GalN Ac-sialyltransferase, which indicates that 2,6-linked NeuN Ac group represents an immunodominant component of some Pr antigens. 相似文献
7.
The conformational properties of the oligosaccharide chain of GM1 ganglioside containingN-glycolyl-neuraminic acid, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-were found to fix the relative orientitation of the three saccharides, while the glycosidic linkage of the terminal -Gal-was found to be quite mobile as the -Gal-(1-3)--GalNAc-disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containingN-acetyl-neuraminic acid and neuraminic acid [1].Abbreviations Ganglioside nomenclature is in accordance with Svennerholm [23] and the IUPAC-IUB Recommendations [24] GM3(Neu5Ac)
II3Neu5AcLacCer, -Neu5Ac-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer
- GM3(Neu5Gc)
II3Neu5GcLacCer, -Neu5Gc-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer
- GM1(Neu5Ac)
II3Neu5AcGgOse4Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer
- GM1(Neu5Gc)
II3Neu5GcGgOse4Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer
- GM1(Neu)
II3NeuGgOse4Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu-(2-3)]--Glc-(1-1)-Cer
- GD1a
IV3Neu5AcII3Neu5AcGgOse4Cer, -Neu5Ac-(2-3)--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer
- GalNAc-GD1a
IV4GalNAcIV3Neu5AcII3Neu5AcGgOse4Cer, -GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer
- Neu
neuraminic acid
- Neu5Ac
N-acetyl-neuraminic acid
- Neu5Gc
N-glycolyl-neuraminic acid
- Cer
ceramide 相似文献
8.
Narcolepsy has a 98% association with the DR2-Dw2/DQw1 haplotype. To establish if a disease-specific allele is present in narcolepsy, a cDNA library was made from a B-cell line from a DR2,4/DQw1,3 narcoleptic. Clones encoding the two expressed DR2
chains, along with DQw1 and chains, were isolated and completely sequenced. The coding regions of these four genes were similar to published nucleotide and protein sequences from corresponding healthy controls, with some minor exceptions. The 3 untranslated region of one of the DR2
genes in the narcoleptic was extended by 42 bp. Complete sequences were not available for DQw1.2 or from healthy individuals, but first domain nucleotide sequences showed only a single nonproductive difference in DQ. Partial protein sequences of both DQ and from published data were identical. Although the effects of minor differences cannot be ruled out completely, it is concluded that there are probably no narcolepsy-specific DR
or DQ / sequences, and that the alleles found in narcolepsy are representative of those found in the healthy population. 相似文献
9.
Claudia P. Spampinato Piotr Paneth Marion H. O'Leary Carlos S. Andreo 《Photosynthesis research》1991,28(2):69-76
Structural analogues of the NADP+ were studied as potential coenzymes and inhibitors for NADP+ dependent malic enzyme from Zea mays L. leaves. Results showed that 1, N6-etheno-nicotinamide adenine dinucleotide phosphate ( NADP+), 3-acetylpyridine-adenine dinucleotide phosphate (APADP+), nicotinamide-hypoxanthine dinucleotide phosphate (NHDP+) and -nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate (23NADPc+) act as alternate coenzymes for the enzyme and that there is little variation in the values of the Michaelis constants and only a threefold variation in Vmax for the five nucleotides. On the other hand, thionicotinamide-adenine dinucleotide phosphate (SNADP+), 3-aminopyridine-adenine dinucleotide phosphate (AADP+), adenosine 2-monophosphate (2AMP) and adenosine 2: 3-cyclic monophosphate (23AMPc) were competitive inhibitors with respect to NADP+, while -nicotinamide adenine dinucleotide 3-phosphate (3NADP+), NAD+, adenosine 3-monophosphate (3AMP), adenosine 2: 5-cyclic monophosphate (25AMPc), 5AMP, 5ADP, 5ATP and adenosine act as non-competitive inhibitors. These results, together with results of semiempirical self-consistent field-molecular orbitals calculations, suggest that the 2-phosphate group is crucial for the nucleotide binding to the enzyme, whereas the charge density on the C4 atom of the pyridine ring is the major factor that governs the coenzyme activity.Abbreviations NADP+
1, N6-etheno-nicotinamide adenine dinucleotide phosphate
- NHDP+
nicotinamide-hypoxanthine dinucleotide phosphate
- APADP+
3-acetylpyridine-adenine dinucleotide phosphate
- SNADP+
thionicotinamide-adenine dinucleotide phosphate
- AADP+
3-aminopyridine-adenine dinucleotide phosphate
- 23NADPc+
-nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate
- 3NADP+
-nicotinamide adenine dinucleotide 3-phosphate
- 2AMP
adenosine 2-monophosphate
- 3AMP
adenosine 3-monophosphate
- 23AMPc
adenosine 2: 3 monophosphate cyclic
- A
adenosine
- RuBP
ribulose 1,5-bisphosphate
- SCF-MO
Self-Consistent Field-Molecular Orbitals (method) 相似文献
10.
Lutz Birnbaumer Ning Qin Riccardo Olcese Erwin Tareilus Daniela Platano Jim Costantin Enrico Stefani 《Journal of bioenergetics and biomembranes》1998,30(4):357-375
Calcium channel subunits have profound effects on how 1 subunits perform. In this article we summarize our present knowledge of the primary structures of subunits as deduced from cDNAs and illustrate their different properties. Upon co-expression with 1 subunits, the effects of subunits vary somewhat between L-type and non-L-type channels mostly because the two types of channels have different responses to voltage which are affected by subunits, such as long-lasting prepulse facilitation of 1C (absent in 1E) and inhibition by G protein dimer of 1E, absent in 1C. One subunit, a brain 2a splice variant that is palmitoylated, has several effects not seen with any of the others, and these are due to palmitoylation. We also illustrate the finding that functional expression of 1 in oocytes requires a subunit even if the final channel shows no evidence for its presence. We propose two structural models for Ca2+ channels to account for 1 alone channels seen in cells with limited subunit expression. In one model, dissociates from the mature 1 after proper folding and membrane insertion. Regulated channels seen upon co-expression of high levels of would then have subunit composition 1. In the other model, the chaperoning remains associated with the mature channel and 1 alone channels would in fact be 1 channels. Upon co-expression of high levels of the regulated channels would have composition [1]. 相似文献
11.
H. Hartmann W. Steigemann H. Reuscher F. Parak 《European biophysics journal : EBJ》1987,14(6):337-348
The refinement of X-ray structural data gives the mean square displacements, x
2, at each position in the protein molecule. In order to get information on the significance of such values different refinement methods have been compared. The metmyoglobin structure was determined at 300 K and x
2-values were obtained with the restrained refinement procedure in reciprocal space of Konnert and Hendrickson. A comparison with the results of Frauenfelder et al. was used for an error estimation. The inclusion of surface bound water increases the accuracy of the results but does not change the general picture. For erythrocruorin (CTT3) a refinement was performed in reciprocal space and compared with a refinement in real space performed earlier. The x
2-values obtained from both procedures are similar although the reciprocal space refinement gives results which are physically more reasonable.A comparison of the disorder in myoglobin and erythrocruorin showed that the structural similarity results in a similarity in the disorder. Contacts of molecules in the crystal do not dominate the disorder although they locally influence x
2-values. CTT3 shows large disorder in the heme region in contrast to myoglobin. The differences in the rigidity of the F-helix can be correlated with the oxygen affinities supporting models for O2 binding developed by Frauenfelder et al. 相似文献
12.
Atriplex gmelini plants were regenerated via organogensis from hypocotyl explants. Callus lines were induced from the hypocotyl explants on Linsmaier and Skoog (LS) medium supplemented with 1 M benzyladenine and 5 M -naphthaleneacetic acid in the dark. Shoots were regenerated from the callus lines on LS medium supplemented with 20 M thidiazuron and 0.1 M -naphthaleneacetic acid under a high-intensity light condition (450 mol m–2 s–1). The regenerated shoots were rooted on LS medium without growth regulators to obtain fully developed plants. We succeeded in transforming Atriplex gmelini from callus lines using Agrobacterium tumefaciens. 相似文献
13.
Antti Seppo Leena Penttilä Anne Leppänen Hannu Maaheimo Ritva Niemelä Jari Helin Jean-Michel Wieruszeski Ossi Renkonen 《Glycoconjugate journal》1994,11(3):217-225
1,3-Galactosylation of radiolabelled bi-antennary acceptors Gal1-4GlcNAc1-3(Gal1-4GlcNAc1-6)Gal-R (R=1-OH, 1-4GlcNAc or 1-4Glc) with bovine thymus 1,3-galactosyltransferase was studied. At all stages of the reactions the three acceptors reacted faster at the 1 6 linked arm than at the 1 3 linked branch. Hence, in addition to the doubly 1,3-galactosylated products, practically pure Gal1-4GlcNAc1-3(Gal1-3Gal1-4GlcNAc1-6)Gal-R could be obtained from the three acceptors in reactions that had proceeded to near completion. The isomeric mono-1,3-galactosylated products were identified by using exoglycosidases to remove the branches unprotected by 1,3-galactoses and by subsequently identifying the resulting linear glycans chromatographically.Abbreviations Gal
d-galactose
- GlcNAc
N-acetyl-d-glucosamine
- Lac
lactose
- LacNAc
Gal1-4GlcNAc
- MH
maltoheptaose
- MP
maltopentaose
- MT
maltotriose
- MTet
maltotetraose
- WGA
wheat germ agglutinin
- 3
position 3 of the galactose unit of LacNAc or Lac
- 6
position 6 of the galactose unit of LacNAc or Lac 相似文献
14.
We analysed the stable isotope composition of emitted N2O in a one-year field experiment (June 1998 to April 1999) in unfertilized controls, and after adding nitrogen by applying slurry or mineral N (calcium ammonium nitrate). Emitted N2O was analysed every 2–4 weeks, with additional daily sampling for 10 days after each fertilizer application. In supplementary soil incubations, the isotopic composition of N2O was measured under defined conditions, favouring either denitrification or nitrification. Soil incubated for 48 h under conditions favouring nitrification emitted very little N2O (0.024 mol gdw
–1) and still produced N2O from denitrification. Under denitrifying incubation conditions, much more N2O was formed (0.91 mol gdw
–1 after 48 h). The isotope ratios of N2O emitted from denitrification stabilized at 15N = –40.8 ± 5.7 and 18O = 2.7 ± 6.3. In the field experiment, the N2O isotope data showed no clear seasonal trends or treatment effects. Annual means weighted by time and emission rate were 15N = –8.6 and 18O = 34.7 after slurry application, 15N = –4.6 and 18O = 24.0 after mineral fertilizer application and 15N = –6.4 and 18O = 35.6 in the control plots, respectively. So, in all treatments the emitted N2O was 15N-depleted compared to ambient air N2O (15N = 11.4 ± 11.6, 18O = 36.9 ± 10.7). Isotope analyses of the emitted N2O under field conditions per se allowed no unequivocal identification of the main N2O producing process. However, additional data on soil conditions and from laboratory experiments point to denitrification as the predominant N2O source. We concluded (1) that the isotope ratios of N2O emitted from the field soil were not only influenced by the source processes, but also by microbial reduction of N2O to N2 and (2) that N2O emission rates had to exceed 3.4 mol N2O m–2 h–1 to obtain reliable N2O isotope data. 相似文献
15.
The present paper reports our attempts to determine whether the inclusion of 0.0014 mM Zn++ within a hydroponic culture medium affects the ability of 12-day-old Zea mays, cv. SS-522 to take-up [3H]-aflatoxin B1. Data from the corollary experiment, i.e., whether inclusion of aflatoxin affects the ability of Zea mays, cvs. Truckers White, X-Sweet and Merit to take-up 65ZnCl2 are presented also. This report is a preliminary to one regarding an in-progress analysis of whether pollutant levels of Zn++ affect aflatoxin uptake and distribution. In the absence of irrigating seedlings, which were grown in Perlite containing 65ZnCl2, with a solution containing mixed aflatoxins, the stem contained the greatest amount of label with root plus seed the next highest and the leaf the least for each of the cvs. In contrast, when the seedlings were irrigated with a solution containing mixed aflatoxins, the root plus seed contained either an amount nearly identical to (cv. Truckers White) or in excess of that within the stem (cvs. X-Sweet and Merit). Calculation of the percentages of aflatoxin-induced diminutions in leaf, stem and root label suggested that the aflatoxins interfered with the translocation of 65ZnCl2 from the root to the stem and leaf, at least for cvs X-Sweet and Merit. When 0.0014mM Zn++ as ZnSO4 was added to an incubation medium in which 12-day-old seedlings were suspended and plant growth assessed over 72 hours, a 15% increase (significant at 0.05 level) in seedling height over that of Zn++-deficient plants was observed. No differences in [3H]-aflatoxin B1 uptake were noted between those seedlings which were grown in either Zn++-containing or lacking media. Less than one % of the[3H]-aflatoxin B1 which was taken-up was recovered within chloroform extracts of the seedlings. The distributions of radioactivity from [3H]-aflatoxin B1 for leaf, stem, seed and root were 0, 57, 26 and 19% and 0, 26, 58 and 18% for Zn++-containing and -lacking media, respectively. 相似文献
16.
The continuous control of the maximum position of the dye absorption band (the zero of the derivative dD
()/d of the cell's optical density D
()) in a nematic matrix is demonstrated experimentally, as a result of changing the angle between the optical axis of a planar-oriented sample and the plane of polarization of absorbed light incident normal to the optical axis. The theory proposed describes quantitatively the experimental dependence (). The rotation of the polarizer with given frequency results in the spectral position modulation of the solute band maximum () within (=0°)–(90°)=700 cm–1. 相似文献
17.
Ben A. Bulthuis Gregory M. Koningstein Adriaan H. Stouthamer Henk W. van Verseveld 《Antonie van Leeuwenhoek》1993,63(1):1-16
The magnitude of the proton motive force (p) and its constituents, the electrical () and chemical potential (-ZpH), were established for chemostat cultures of a protease-producing, relaxed (rel
–) variant and a not protease-producing, stringent (rel
+) variant of an industrial strain ofBacillus licheniformis (respectively referred to as the A- and the B-type). For both types, an inverse relation of p with the specific growth rate was found. The calculated intracellular pH (pHin) was not constant but inversely related to . This change in pHin might be related to regulatory functions of metabolism but a regulatory role for pHin itself could not be envisaged. Measurement of the adenylate energy charge (EC) showed a direct relation with for glucose-limited chemostat cultures; in nitrogen-limited chemostat cultures, the EC showed an approximately constant value at low and an increased value at higher . For both limitations, the ATP/ADP ratio was directly related to .The phosphorylation potential (G'p) was invariant with . From the values for G'p and p, a variable H+/ATP-stoichiometry was inferred: H+/ATP=1.83+0.52µ, so that at a given H+/O-ratio of four (4), the apparent P/O-ratio (inferred from regression analysis) showed a decline of 2.16 to 1.87 for =0 to max (we discuss how more than half of this decline will be independent of any change in internal cell-volume). We propose that the constancy of G'p and the decrease in the efficiency of energy-conservation (P/O-value) with increasing are a way in which the cells try to cope with an apparent less than perfect coordination between anabolism and catabolism to keep up the highest possible with a minimum loss of growth-efficiency. Protease production in nitrogen-limited cultures as compared to glucose-limited cultures, and the difference between the A- and B-type, could not be explained by a different energy-status of the cells.Abbreviations CCCP
carbonylcyanide-p-trichloromethoxyphenylhydrazone
- DW
dry weight of biomass
- F
Faraday's constant, 96.6 J/(mV × mol)
- Fo
chemostat outflow-rate (ml/h)
- FCCP
carbonylcyanide-p-trifluoromethoxyphenylhydrazone
- G'p
phosphorylation potential, the Gibbs energy change for ATP-synthesis from ADP and Pi
- G'0p
standard Gibbs energy change at specified conditions
- H+/ATP
number of protons translocated through
- ATP
synthase in synthesis of one ATP
- H+/O
protons translocated during transfer of 2 electrons from substrate to oxygen
-
specific growth rate (1/h)
- H+
transmembrane electrochemical proton potential, J/mol
- Mb
molar weight (147.6 g/mol) of bacteria with general cell formula C6.0H10.8O3.0N1.2
- pHout,in
extracellular, intracellular pH
- Pi
(intracellular) inorganic phosphate
- p
proton motive force, mV
- pH
transmembrane pH-difference
-
transmembrane electrical potential, mV
- P/O
number of ADP phosphorylated to ATP upon reduction of one O2– to H2O by two electrons transferred through the electron transfer chain
- P/O
(H+/O) × (H+/ATP)–1
- P/OF, P/ON
P/O with the two electrons donated by resp. (NADH + H+) and FADH
- q
specific rate of consumption or production (mol/g DW × h)
-
rel
+,rel
–
stringent, relaxed genotype
- R
universal gas constant, 8.36 J/(mol × degree)
- T
absolute temperature
- TPMP+
triphenylmethylphosphonium ion
- TPP+
tetraphenyl phosphonium ion
- Y
growth yield, g DW/mol
- Z
conversion constant=61.8 mV for 310 K (37 °C)
- ZpH
transmembrane proton potential or chemical potential, mV 相似文献
18.
Bellizzi Mary C. Dutta-Roy Asim K. James W. Philip T. 《Molecular and cellular biochemistry》1997,170(1-2):187-193
The role of -tocopherol uptake system in human erythrocyte in the uptake of plasma -tocopherol has been suggested. However no information is available on -tocopherol uptake activity of human erythrocytes in the presence of high levels of D-glucose which is known to lead to pathological alterations in different cells including human erythrocytes. Therefore, in order to examine the effect of D-glucose on the binding of -tocopherol to human erythrocytes, the binding characteristics of -tocopherol to these cells were established first. Binding of [3H]-tocopherol to human erythrocytes was both saturable and specific. Scatchard analysis of -tocopherol binding to these cells showed the presence of two independent classes of binding sites with widely different affinities. The high affinity binding sites had a dissociation constant (Kd1) of 90 nM with a binding capacity (n1) of 900 sites per cell, whereas the low affinity binding sites had a dissociation constant (Kd2) of 5.2 M and a binding capacity (n2) of 105,400 sites per cell. Trypsin treatment abolished all the -tocopherol binding activity. Competition for the binding of -tocopherol to human erythrocytes was effective with other homologues of -tocopherol (-tocopherol, -tocopherol and -tocopherol) and their potency was almost equal to -tocopherol itself. The order of preference was -tocopherol > -tocopherol -tocopherol -tocopherol. Incubation of human erythrocytes with various concentrations of D-glucose did not affect -tocopherol uptake activity. Our data demonstrate the presence of an -tocopherol uptake system in human erythrocytes and that the -tocopherol uptake activity is not modulated by the presence of D-glucose. 相似文献
19.
Bodrova ME Brailovskaya IV Efron GI Starkov AA Mokhova EN 《Biochemistry. Biokhimii?a》2003,68(4):391-398
At low Ca2+ concentrations the pore of the inner mitochondrial membrane can open in substates with lower permeability (Hunter, D. R., and Haworth, R. A. (1979) Arch. Biochem. Biophys., 195, 468-477). Recently, we showed that Ca2+ loading of mitochondria augments the cyclosporin A-dependent decrease in transmembrane potential () across the inner mitochondrial membrane caused by 10 M myristic acid but does not affect the stimulation of respiration by this fatty acid. We have proposed that in our experiments the pore opened in a substate with lower permeability rather than in the classic state (Bodrova, M. E., et al. (2000) IUBMB Life, 50, 189-194). Here we show that under conditions lowering the probability of classic pore opening in Ca2+-loaded mitochondria myristic acid induces the cyclosporin A-sensitive decrease and mitochondrial swelling more effectively than uncoupler SF6847 does, though their protonophoric activities are equal. In the absence of Pi and presence of succinate and rotenone (with or without glutamate) cyclosporin A either reversed or only stopped decrease induced by 5 M myristic acid and 5 M Ca2+. In the last case nigericin, when added after cyclosporin A, reversed the decrease, and the following addition of EGTA produced only a weak (if any) increase. In Pi-containing medium (in the presence of glutamate and malate) cyclosporin A reversed the decrease. These data show that the cyclosporin A-sensitive decrease in by low concentrations of fatty acids and Ca2+ cannot be explained by specific uncoupling effect of fatty acid. We propose that: 1) low concentrations of Ca2+ and fatty acid induce the pore opening in a substate with a selective cation permeability, and the cyclosporin A-sensitive decrease results from a conversion of to pH gradient due to the electrogenic cation transport in mitochondria; 2) the ADP/ATP-antiporter is involved in this process; 3) higher efficiency of fatty acid compared to SF6847 in the Ca2+-dependent pore opening seems to be due to its interaction with the nucleotide-binding site of the ADP/ATP-antiporter and higher affinity of fatty acids to cations. 相似文献
20.
Summary The self-condensation of 2(3)-O-glycyl esters of adenosine, adenosine-5-(O-methylphosphate) and P1, P2-diadenosine-5-pyrophosphate in 6.2 mM solutions at pH 8.0 and -5°C in the presence of 12.5 mM poly(U) yields approximately 3 times as much diketopiperazine as reactions without poly(U). As the concentration of 2(3)-O-(glycyl)-P1, P2-diadenosine-5-pyrophosphate is decreased from 6.2 mM to 1.5 mM the yield of diketopiperazine in the presence of poly(U) decreases slightly from 6.6% to 5.2%, whereas, in the absence of poly(U) the yield of diketopiperazine decreases substantially from 2.4% to 0.75%. The enhanced yield of diketopiperazine that is attributed to the template action of poly(U) is temperature dependent and is observed only at temperatures below 10°C (5°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) and below 23°C (15°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-P1, P2-diadenosine-5-pyrophosphate. The absence of a template effect at high temperatures is attributed to the melting of the organized helices. The hydrolysis half-lives at pH 8.0 and -5°C of 2(3)-O-(glycyl)-adenosine, 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate), 2(3)-O-(glycyl)-P1, P2-diadenosine-5-pyrophosphate, and 5-O-(glycyl)-adenosine in the presence of poly(U) are substantially larger than their half-lives in the absence of poly(U). The condensation of 2(3)-O-(glycyl)-adenosine yields 5% of 5-O-(glycyl)-adenosine in the presence of poly(U) compared to 0.7% in the absence of poly(U).Abbreviations DKP
diketopiperazine
- (gly)2
glycylglycine
- (gly)3
glycylglycylglycine
- AppA-gly
2(3)-O-(glycyl)-P1, P2-diadenosine-5-pyrophosphate
- MepA-gly
2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate)
- Ado-2(3)-gly
2(3)-O-(glycyl)-adenosine
- Ado-5-gly
5-O-(glycyl)-adenosine
- Boc-gly
N-tert-butyloxycarbonylglycine
- AppA
P1, P2-diadenosine-5-pyrophosphate
- MepA
adenosine-5-(O-methylphosphate)
- AppA-Boc-gly
2(3)-O-(Boc-glycyl)-P1, P2-diadenosine-5-pyrophosphate
- Ado-5-Boc-gly
5-O-(Boc-glycyl)-adenosine
- Ado-2(3)-Boc-gly
2(3)-O-(Boc-glycyl)-adenosine 相似文献