共查询到20条相似文献,搜索用时 31 毫秒
1.
F1-ATPase is a catalytic part of the F1Fo-ATP synthase molecular motor. The cooperative hydrolysis of ATP at three catalytic sites of F1-ATPase is accompanied by the rotation of the central γ-subunit inside a cylinder formed by three α-subunits and three β-subunits. Experimental works of different authors have shown that the γ-subunit rotates with irregular dwells. A simple kinetic model suggested in this article provides an explanation as to why dwells occur during the rotation of F1-ATPase. According to this model, rotation dwells happen as a result of deterministic chaos, which in turn occurs at rate constants that are close to those demonstrated experimentally. The time duration of dwells in the model is in agreement with that observed experimentally. Our model explains the known irregular occupancy of catalytic sites of F1-ATPase by nucleotides. 相似文献
2.
V-type Na+-ATPase from Entercoccus hirae consists of nine kinds of subunits (NtpA3, B3, C1, D1, E1−3, F1−3, G1, I1, and K10) which are encoded by the ntp operon. The amino acid sequences of the major subunits, A, B, and K (proteolipid), were highly similar to those of A, B,
and c subunits of eukaryotic V-ATPases, and those of β, α, and c subunits of F-ATPases. We modeled the A and B subunits by
homology modeling using the structure of β and α subunits of F-ATPase, and obtained an atomic structure of NtpK ring by X-ray
crystallography. Here we briefly summarize our current models of the whole structure and mechanism of the E. hirae V-ATPase. 相似文献
3.
Shimizu M Yamashita D Yamaguchi T Hirose F Osumi T 《Molecular and cellular biochemistry》2006,287(1-2):33-42
The aim of the present work was to study the effects of an unilateral ischaemic-reperfusion injury on Na+, K+-ATPase activity, α1 and β1 subunits protein and mRNA abundance and ATP content in cortical and medullary tissues from postischaemic and contralateral kidneys. Right renal artery was clamped for 40 min followed by 24 and 48 h of reperfusion. Postischaemic and contralateral renal function was studied cannulating the ureter of each kidney. Postischaemic kidneys after 24 (IR24) and 48 (IR48) hours of reperfusion presented a significant dysfunction. Na+, K+-ATPase α1 subunit abundance increased in IR24 and IR48 cortical tissue and β1 subunit decreased in IR48. In IR24 medullary tissue, α1 abundance increased and returned to control values in IR48 while β1 abundance was decreased in both periods. Forty minutes of ischaemia without reperfusion (I40) promoted an increment in α1 mRNA in cortex and medulla that normalised after 24 h of reperfusion. β1 mRNA was decreased in IR24 medullas. No changes were observed in contralateral kidneys. This work provides evidences that after an ischaemic insult α1 and β1 protein subunit abundance and mRNA levels are independently regulated. After ischaemic-reperfusion injury, cortical and medullary tissue showed a different pattern of response. Although ATP and Na+, K+-ATPase activity returned to control values, postischemic kidney showed an abnormal function after 48 h of reflow. 相似文献
4.
Subunit E of the vacuolar ATPase (V-ATPase) contains an N-terminal extended α helix (Rishikesan et al. J Bioenerg Biomembr
43:187–193, 2011) and a globular C-terminal part that is predicted to consist of a mixture of α-helices and β-sheets (Grüber et al. Biochem
Biophys Res Comm 298:383–391, 2002). Here we describe the production, purification and 2D structure of the C-terminal segment E133-222 of subunit E from Saccharamyces cerevisiae V-ATPase in solution based on the secondary structure calculation from NMR spectroscopy studies. E133-222 consists of four β-strands, formed by the amino acids from K136-V139, E170-V173, G186-V189, D195-E198 and two α-helices,
composed of the residues from R144-A164 and T202-I218. The sheets and helices are arranged as β1:α1:β2:β3:β4:α2, which are
connected by flexible loop regions. These new structural details of subunit E are discussed in the light of the structural
arrangements of this subunit inside the V1- and V1VO ATPase. 相似文献
5.
Ming Tang Gemma Comellas Leonard J. Mueller Chad M. Rienstra 《Journal of biomolecular NMR》2010,48(2):103-111
High resolution 13C-detected solid-state NMR spectra of the deuterated beta-1 immunoglobulin binding domain of the protein G (GB1) have been
collected to show that all 15N, 13C′, 13Cα and 13Cβ sites are resolved in 13C–13C and 15N–13C spectra, with significant improvement in T
2 relaxation times and resolution at high magnetic field (750 MHz). The comparison of echo T
2 values between deuterated and protonated GB1 at various spinning rates and under different decoupling schemes indicates that
13Cα T
2′ times increase by almost a factor of two upon deuteration at all spinning rates and under moderate decoupling strength,
and thus the deuteration enables application of scalar-based correlation experiments that are challenging from the standpoint
of transverse relaxation, with moderate proton decoupling. Additionally, deuteration in large proteins is a useful strategy
to selectively detect polar residues that are often important for protein function and protein–protein interactions. 相似文献
6.
Summary In this study, the variety of sugar residues in the gut glycoconjugates of Triturus carnifex (Amphibia, Caudata) are investigated by carbohydrate conventional histochemistry and lectin histochemistry. The oesophageal
surface mucous cells contained acidic glycoconjugates, with residues of GalNAc, Gal β1,3 GalNAc and (GlcNAc β1,4)
n
oligomers. The gastric surface cells mainly produced neutral glycoproteins with residues of fucose, Gal β1-3 GalNAc, Gal-αGal,
and (GlcNAc β1,4)
n
oligomers in N- and O-linked glycans, as the glandular mucous neck cells, with residues of mannose/glucose, GalNAc, Gal β1,3
GalNAc, (GlcNAc β1,4)
n
oligomers and fucose linked α1,6 or terminal α1,3 or α1,4 in O-linked glycans. The oxynticopeptic tubulo-vesicular system
contained neutral glycoproteins with N- and O-linked glycans with residues of Gal-αGal, Gal β1-3 GalNAc and (GlcNAc β1,4)
n
oligomers; Fuc linked α1,2 to Gal, α1,3 to GlcNAc in (poly)lactosamine chains and α1,6 to GlcNAc in N-linked glycans. Most
of these glycoproteins probably corresponds to the H+K+-ATPase β-subunit. The intestinal goblet cells contained acidic glycoconjugates, with residues of GalNAc, mannose/ glucose,
(GlcNAc β1,4)
n
oligomers and fucose linked α1,2 to Gal in O-linked oligosaccharides. The different composition of the mucus in the digestive
tracts may be correlated with its different functions. In fact the presence of abundant sulphation of glycoconjugates, mainly
in the oesophagus and intestine, probably confers resistance to bacterial enzymatic degradation of the mucus barrier. 相似文献
7.
F1-ATPase, composed of α, β, γ, δ, and ? subunits, is a unique enzyme in terms of its rotational catalytic activity. The smallest unit showing this function is the α3β3γ complex. We have investigated the α3β3γ?ΔC (?ΔC, truncated ?) complex from thermophilic Bacillus PS3 (TF1′, 360 kDa) in the solution state by using the combination of extensive deuteration, segmental-labeling, and CRINEPT (cross-correlated relaxation-enhanced polarization transfer) NMR. Well-resolved CRINEPT-HMQC (heteronuclear multiple-quantum correlation) spectra of partially 15N-labeled TF1′ were obtained for this huge and asymmetric protein complex. The spectrum of the C-terminal domain of the β subunit revealed that the open form of the β subunit in the TF1′ complex is similar to that of the free β monomer. The open β subunit in the TF1′ complex does not exhibit high affinity for nucleotides unlike the monomer, but this is in agreement with the results of single-molecule analysis of TF1α3β3γ. On the other hand, the closed form of the β subunit in the TF1′ complex was shown to be distinct from that of the nucleotide-bound β monomer. This is consistent with a previous report that the closed form of the TF1β monomer could be a catalytically activated state. The loop between the N-terminal β-barrel and the central domain is highly flexible in the TF1′ complex, in contrast to that in the α3β3 hexamer, suggesting that it is affected by the presence of the γ subunit in this area. 相似文献
8.
Sandoval A Arikkath J Monjaraz E Campbell KP Felix R 《Cellular and molecular neurobiology》2007,27(7):901-908
(1) Voltage-gated Ca2+ (CaV) channels are multi-subunit membrane complexes that allow depolarization-induced Ca2+ influx into cells. The skeletal muscle L-type CaV channels consist of an ion-conducting CaV1.1 subunit and auxiliary α2δ−1, β1 and γ1 subunits. This complex serves both as a CaV channel and as a voltage sensor for excitation–contraction coupling. (2) Though much is known about the mechanisms by which
the α2δ−1 and β1 subunits regulate CaV channel function, there is far less information on the γ1 subunit. Previously, we characterized the interaction of γ1 with the other components of the skeletal CaV channel complex, and showed that heterologous expression of this auxiliary subunit decreases Ca2+ current density in myotubes from γ1 null mice. (3) In the current report, using Western blotting we show that the expression of the CaV1.1 protein is significantly lower when it is heterologously co-expressed with γ1. Consistent with this, patch-clamp recordings showed that transient transfection of γ1 drastically inhibited macroscopic currents through recombinant N-type (CaV2.2/α2δ−1/β3) channels expressed in HEK-293 cells. (4) These findings provide evidence that co-expression of the auxiliary γ1 subunit results in a decreased expression of the ion-conducting subunit, which may help to explain the reduction in Ca2+ current density following γ1 transfection. 相似文献
9.
Previous studies in expression systems have found different ion activation of the Na+/K+-ATPase isozymes, which suggest that different muscles have different ion affinities. The rate of ATP hydrolysis was used
to quantify Na+,K+-ATPase activity, and the Na+ affinity of Na+,K+-ATPase was studied in total membranes from rat muscle and purified membranes from muscle with different fiber types. The
Na+ affinity was higher (K
m lower) in oxidative muscle compared with glycolytic muscle and in purified membranes from oxidative muscle compared with
glycolytic muscle. Na+,K+-ATPase isoform analysis implied that heterodimers containing the β1 isoform have a higher Na+ affinity than heterodimers containing the β2 isoform. Immunoprecipitation experiments demonstrated that dimers with α1 are responsible for approximately 36% of the total Na,K-ATPase activity. Selective inhibition of the α2 isoform with ouabain suggested that heterodimers containing the α1 isoform have a higher Na+ affinity than heterodimers containing the α2 isoform. The estimated K
m values for Na+ are 4.0, 5.5, 7.5 and 13 mM for α1β1, α2β1, α1β2 and α2β2, respectively. The affinity differences and isoform distributions imply that the degree of activation of Na+,K+-ATPase at physiological Na+ concentrations differs between muscles (oxidative and glycolytic) and between subcellular membrane domains with different
isoform compositions. These differences may have consequences for ion balance across the muscle membrane. 相似文献
10.
Maria Grazia Di Certo Enrico M Batassa Ida Casella Annalucia Serafino Aristide Floridi Claudio Passananti Paola Molinari Elisabetta Mattei 《BMC cell biology》2008,9(1):56
Background
Chimeric proteins obtained by the fusion of a G protein-coupled receptor (GPCR) sequence to the N-terminus of the G protein α-subunit have been extensively used to investigate several aspects of GPCR signalling. Although both the receptor and the G protein generally maintain a fully functional state in such polypeptides, original observations made using a chimera between the β2-adrenergic receptor (β2AR) and Gαs indicated that the fusion to the α-subunit resulted in a marked reduction of receptor desensitization and down-regulation. To further investigate this phenomenon, we have compared the rates of internalization and recycling between wild-type and Gαs-fused β2AR. 相似文献11.
Milgrom YM 《Biochemistry. Biokhimii?a》2011,76(11):1253-1261
MgADP and MgATP binding to catalytic sites of βY341W-α3β3Γ subcomplex of F1-ATPase from thermophilic Bacillus PS3 has been assessed using their effect on the enzyme inhibition by 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl). It
was assumed that NBD-Cl can inhibit only when catalytic sites are empty, and inhibition is prevented if a catalytic site is
occupied with a nucleotide. In the absence of an activator, MgADP and MgATP protect βY341W-α3β3Γ sub-complex from inhibition by NBD-Cl by binding to two catalytic sites with an affinity of 37 μM and 12 mM, and 46 μM and
15 mM, respectively. In the presence of an activator lauryldimethylamine-N-oxide (LDAO), MgADP protects βY341W-α3β3Γ subcomplex from inhibition by NBD-Cl by binding to a catalytic site with a K
d of 12 mM. Nucleotide binding to a catalytic site with affinity in the millimolar range has not been previously revealed in
the fluorescence quenching experiments with βY341W-α3β3Γ subcomplex. In the presence of activators LDAO or selenite, MgATP protects βY341W-α3β3Γ subcomplex from inhibition by NBD-Cl only partially, and the enzyme remains sensitive to inhibition by NBD-Cl even at MgATP
concentrations that are saturating for ATPase activity. The results support a bi-site mechanism of catalysis by F1-ATPases. 相似文献
12.
G-matrix FT projection NMR spectroscopy was employed for resonance assignment of the 79-residue subunit c of the Escherichia coli F1F0 ATP synthase embedded in micelles formed by lyso palmitoyl phosphatidyl glycerol (LPPG). Five GFT NMR experiments, that is,
(3,2)D HNNCO, L-(4,3)D HNNC
αβ
C
α, L-(4,3)D HNN(CO)C
αβ
C
α, (4,2)D HACA(CO)NHN and (4,3)D HCCH, were acquired along with simultaneous 3D 15N, 13Caliphatic, 13Caromatic-resolved [1H,1H]-NOESY with a total measurement time of ∼43 h. Data analysis resulted in sequence specific assignments for all routinely
measured backbone and 13Cβ shifts, and for 97% of the side chain shifts. Moreover, the use of two G2FT NMR experiments, that is, (5,3)D HN{N,CO}{C
αβ
C
α} and (5,3)D {C
αβ
C
α}{CON}HN, was explored to break the very high chemical shift degeneracy typically encountered for membrane proteins. It is shown
that the 4D and 5D spectral information obtained rapidly from GFT and G2FT NMR experiments enables one to efficiently obtain (nearly) complete resonance assignments of membrane proteins.
Qi Zhang, Hanudatta S. Atreya, Douglas E. Kamen, Mark E. Girvin and Thomas Szyperski—New York Consortium on Membrane Protein
Structure. 相似文献
13.
Overload of intracellular Ca2+ has been implicated in the pathogenesis of neuronal disorders, such as Alzheimer’s disease. Various mechanisms produce abnormalities
in intracellular Ca2+ homeostasis systems. L-type Ca2+ channels have been known to be closely involved in the mechanisms underlying the neurodegenerative properties of amyloid-β
(Aβ) peptides. However, most studies of L-type Ca2+ channels in Aβ-related mechanisms have been limited to CaV1.2, and surprisingly little is known about the involvement of CaV1.3 in Aβ-induced neuronal toxicity. In the present study, we examined the expression patterns of CaV1.3 after Aβ25–35 exposure for 24 h and compared them with the expression patterns of CaV1.2. The expression levels of CaV1.3 were not significantly changed by Aβ25–35 at both the mRNA levels and the total protein level in cultured hippocampal neurons. However, surface protein levels of CaV1.3 were significantly increased by Aβ25–35, but not by Aβ35–25. We next found that acute treatment with Aβ25–35 increased CaV1.3 channel activities in HEK293 cells using whole-cell patch-clamp recordings. Furthermore, using GTP pulldown and co-immunoprecipitation
assays in HEK293 cell lysates, we found that amyloid precursor protein interacts with β3 subunits of Ca2+ channels instead of CaV1.2 or CaV1.3 α1 subunits. These results show that Aβ25–35 chronically or acutely upregulates CaV1.3 in the rat hippocampal and human kidney cells (HEK293). This suggests that CaV1.3 has a potential role along with CaV1.2 in the pathogenesis of Alzheimer’s disease. 相似文献
14.
Cavallo A Gnoni A Conte E Siculella L Zanotti F Papa S Gnoni GV 《Journal of bioenergetics and biomembranes》2011,43(4):349-357
Short-term effects of 3,5-L-diiodothyronine (T2) administration to hypothyroid rats on FoF1-ATP synthase activity were investigated in liver mitochondria. One hour after T2 injection, state 4 and state 3 respiration rates were noticeably stimulated in mitochondria subsequently isolated. FoF1-ATP synthase activity, which was reduced in mitochondria from hypothyroid rats as compared to mitochondria from euthyroid
rats, was significantly increased by T2 administration in both the ATP-synthesis and hydrolysis direction. No change in β-subunit mRNA accumulation and protein amount
of the α-β subunit of FoF1-ATP synthase was found, ruling out a T2 genomic effect. In T2-treated rats, changes in the composition of mitochondrial phospholipids were observed, cardiolipin (CL) showing the greatest
alteration. In mitochondria isolated from hypothyroid rats the decrease in the amount of CL was accompanied by an increase
in the level of peroxidised CL. T2 administration to hypothyroid rats enhanced the level of CL and decreased the amount of peroxidised CL in subsequently isolated
mitochondria, tending to restore the CL value to the euthyroid level. Minor T2-induced changes in mitochondrial fatty acid composition were detected. Overall, the enhanced FoF1-ATP synthase activity observed following injection of T2 to hypothyroid rats may be ascribed, at least in part, to an increased level of mitochondrial CL associated with decreased
peroxidation of CL. 相似文献
15.
H. J. Carlisle T. G. Hales B. A. Schlinger 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(4):531-538
Songbirds are widely studied to investigate the hormonal control of behavior. However, little is known about the effects
of steroids on neurotransmission in these birds. We used electrophysiological and pharmacological techniques to characterize
γ-aminobutyric acid (GABA) type A receptors (GABAA) of primary cultured telencephalic and hippocampal neurons from developing zebra finches. Additionally, their modulation
by 17β-estradiol(E2), 5α- and 5β-dihydrotestosterone (DHT), 5α- and 5β-pregnan-3α-ol-20-one, and corticosterone was examined. Whole-cell GABA-evoked
currents were inhibited by picrotoxin (10 μmol l−1) and bicuculline methiodide (10 μmol l−1) and potentiated by pentobarbital (100 μmol l−1) and propofol (3 μmol l−1). Loreclezole (10 μmol l−1) potentiated GABA-evoked currents, suggesting the presence of β2, β3 and/or β4 subunits. Diazepam (1 μmol l−1) potentiated currents, while Zn2+ (1 μmol l−1) caused no inhibition, indicating the presence of γ subunits. 5α- and 5β-Pregnan-3α-ol-20-one (100 nmol l−1) potentiated currents, whereas E2 (1 μmol l−1), 5α- and 5β-DHT (1 μmol l−1), and corticosterone (10 μmol l−1) had no detectable effect. We conclude that zebra finch telencephalic and hippocampal GABAA receptors include α, β, and γ subunits and are similar to their mammalian counterparts in both their biophysical and pharmacological
properties. Additionally, GABA-evoked currents are greatly potentiated by 5α- and 5β-pregnan-3α-ol-20-one but show little
or no acute modulation by sex steroids or corticosterone.
Accepted: 12 November 1997 相似文献
16.
Guennoun-Lehmann S Fonseca JE Horisberger JD Rakowski RF 《The Journal of membrane biology》2007,216(2-3):107-116
Palytoxin (PTX) opens a pathway for ions to pass through Na,K-ATPase. We investigate here whether PTX also acts on nongastric
H,K-ATPases. The following combinations of cRNA were expressed in Xenopus laevis oocytes: Bufo marinus bladder H,K-ATPase α2- and Na,K-ATPase β2-subunits; Bufo Na,K-ATPase α1- and Na,K-ATPase β2-subunits; and Bufo Na,K-ATPase β2-subunit alone. The response to PTX was measured after blocking endogenous Xenopus Na,K-ATPase with 10 μm ouabain. Functional expression was confirmed by measuring 86Rb uptake. PTX (5 nm) produced a large increase of membrane conductance in oocytes expressing Bufo Na,K-ATPase, but no significant increase occurred in oocytes expressing Bufo H,K-ATPase or in those injected with Bufo β2-subunit alone. Expression of the following combinations of cDNA was investigated in HeLa cells: rat colonic H,K-ATPase α1-subunit and Na,K-ATPase β1-subunit; rat Na,K-ATPase α2-subunit and Na,K-ATPase β2-subunit; and rat Na,K-ATPase β1- or Na,K-ATPase β2-subunit alone. Measurement of increases in 86Rb uptake confirmed that both rat Na,K and H,K pumps were functional in HeLa cells expressing rat colonic HKα1/NKβ1 and NKα2/NKβ2. Whole-cell patch-clamp measurements in HeLa cells expressing rat colonic HKα1/NKβ1 exposed to 100 nm PTX showed no significant increase of membrane current, and there was no membrane conductance increase in HeLa cells transfected
with rat NKβ1- or rat NKβ2-subunit alone. However, in HeLa cells expressing rat NKα2/NKβ2, outward current was observed after pump activation by 20 mm K+ and a large membrane conductance increase occurred after 100 nm PTX. We conclude that nongastric H,K-ATPases are not sensitive to PTX when expressed in these cells, whereas PTX does act
on Na,K-ATPase. 相似文献
17.
L. A. Nesterova B. N. Manukhin 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2011,5(1):85-91
The influence of isoprenaline- and propranolole-induced activation and inhibition of β-adrenoreceptors on the specific nonselective
α2-antagonist [3H]RX821002 binding was studied on rat cerebral cortex subcellular membrane fractions. It was shown that the ligand-receptor
interaction for α2-adrenoreceptors corresponded to the model that assumed the presence of one receptor pool and binding of two ligand molecules
to a receptor dimer. The following parameters were determined for [3H]RX821002 binding to α2-adrenoreceptors: K
d1 = 1.57 ± 0.27 nM, B
max = 7.24 ± 1.63 fmol/mg of protein, n = 2. In the case of isoprenaline-induced activation of β-adrenoreceptors the binding of radiolabeled ligand to α2-adrenoreceptors was described by the same model. The affinity of α2-adrenoreceptors for [3H]RX821002 decreased more than twofold (K
d = 3.55 ± 0.02 nM) and the quantity of active receptors increased by 69% (B
max = 12.24 ± 0.06 fmol/mg of protein). Propranolole changed the model of ligand binding, and two pools of receptors were detected
with the following parameters: K
d1 = 0.61 ± 0.02 nM, K
d2 = 3.41 ± 0.13 nM, B
ml = 1.88 ± 0.028 fmol/mg of protein, B
m2 = 9.27 ± 0.08 fmol/mg of protein, n = 2. The data suggest that α2-adrenoreceptors in subcellular membrane fractions from rat cerebral cortex exist in dimeric form. Isoprenaline and propranolole
exhibit modulating effect on the specific antagonist binding to α2-adrenoreceptors, which results in the inhibition and alteration of [3H]RX821002 binding parameters. 相似文献
18.
Eric Mossel Fernando Formaggio Giovanni Valle Marco Crisma Claudio Toniolo Mitsunobu Doi Toshimasa Ishida Quirinus B. Broxterman Johan Kamphuis 《International journal of peptide research and therapeutics》1998,5(2-3):223-225
Summary In order to obtain further information on the role played by phenyl ring position in the Cα-methylated α-amino acid side chain on peptide preferred conformation, the crystal-state structural preferences of Cα-methyl, Cα-phenylglycine peptides have been determined by X-ray diffraction. This study shows that either the fully extended conformation
or the β-bend/310-helical structures are adopted by peptides characterized by this Cα-methylated, β-branched, aromatic α-amino acid. 相似文献
19.
Enterococcus hirae grow well under anaerobic conditions at alkaline pH (pH 8.0) producing acids by glucose fermentation. Bacterial growth was
shown to be accompanied by decrease of redox potential from positive values (~+35 mV) to negative ones (~−220 mV). An oxidizer
copper (II) ions (Cu2+) affected bacterial growth in a concentration-dependent manner (within the range of 0.05 mM to 1 mM) increasing lag phase
duration and decreasing specific growth rate. These effects were observed with the wild-type strain ATCC9790 and the atpD mutant strain MS116 (with absent β subunit of F1 of the FoF1 ATPase) both. Also ATPase activity and proton–potassium ions exchange were assessed with and without N,N′-dicyclohexylcarbodiimide (DCCD), inhibitor of the FoF1 ATPase. In both cases (DCCD ±), even low Cu2+ concentrations had noticeable effect on ATPase activity, but with less visible concentration-dependent manner. Changes in
the number of accessible SH-groups were observed with E. hirae ATCC9790 and MS116 membrane vesicles. In both strains Cu2+ markedly decreased the number of SH-groups in the presence of K+ ions. The addition of ATP increased the amount of accessible SH-groups in ATCC9790 and decreased this number in MS116; Cu2+ blocked ATP-installed increase in SH-groups number in ATCC9790. H+–K+-exchange of bacteria was markedly inhibited by Cu2+, but stronger effects were detected together with DCCD. Moreover, discrimination between Cu2+ and other bivalent cation—Ni2+ was shown. It is suggested that Cu2+ ions inhibit E. hirae cell growth by direct affect on the FoF1 ATPase leading to conformational changes in this protein complex and decrease in its activity. 相似文献
20.
A simple isotope labeling approach for selective 13C/15N backbone labeling of proteins is described. Using {1,2-13C2}-pyruvate as the sole carbon source in bacterial growth media, selective incorporation of 13Cα-13CO spin-pairs into the backbones of protein molecules with medium-to-high levels of 13C-enrichment is possible for a subset of 12 amino acids. The isotope labeling scheme has been tested on a pair of proteins—a
7-kDa immunoglobulin binding domain B1 of streptococcal protein G and an 82-kDa enzyme malate synthase G. A number of protein
NMR applications are expected to benefit from the {1,2-13C2}-pyruvate based protein production. 相似文献