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1.
Takenori Miyamoto Diego Restrepo Edward J. Cragoe Jr. John H. Teeter 《The Journal of membrane biology》1992,127(3):173-183
Summary Olfactory receptor neurons enzymatically dissociated from channel catfish olfactory epithelium were depolarized transiently following dialysis of IP3 or cAMP (added to the patch pipette) into the cytoplasm. Voltage and current responses to IP3 were blocked by ruthenium red, a blocker of an IP3-gated Ca2+-release channel in sarcoplasmic reticulum. In contrast, the responses to cAMP were not blocked by extracellularly applied ruthenium red, nor by l-cis-diltiazem or amiloride and two of its derivatives. The current elicited by cytoplasmic IP3 in neurons under voltage clamp displayed a voltage dependence different from that of the cAMP response which showed marked outward rectification. A sustained depolarization was caused by increased cytoplasmic IP3 or cAMP when the buffering capacity for Ca2+ of the pipette solution was increased, when extracellular Ca2+ was removed or after addition of 20–200 nm charibdotoxin to the bathing solution, indicating that the repolarization was caused by an increase in [Ca
i
] that opened Ca2+-activated K+ channels. The results suggest that different conductances modulated by either IP3 or cAMP are involved in mediating olfactory transduction in catfish olfactory receptor neurons and that Ca2+-activated K+ channels contribute to the termination of the IP3 and cAMP responses.Abbreviations ATP
adenosine 5-triphosphate
- BAPTA
(bis-(o-aminophenoxy)-ethane-N-N-N-N)-tetraacetic acid
- cAMP
adenosine cyclic 3,5-monophosphate
- cGMP
guanosine cyclic 3,5-monophosphate
- CTX
charybdotoxin
- DCB
3,4-dichlorobenzamil
- EDTA
ethylenediaminetetraacetic acid
- EGTA
ethylenglycol-bis-(b-aminoethyl)-N-N-N-N-tetraacetic acid
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- IP3
inositol-1,4,5-triphosphate
- NMDG
N-methyl-d-glucamine
We would like to thank the Tanabe Seiyaku Co., Ltd., for their gift of l-cis-diltiazem. This work was supported by National Institutes of Health grants DC00566 and BRSG S07RR05825. 相似文献
2.
Johannes H. Ippel Virginia Lanzotti Aldo Galeone Luciano Mayol Jacquelien E. van den Boogaart Jeroen A. Pikkemaat Cornelis Altona 《Journal of biomolecular NMR》1995,6(4):403-422
Summary The circular DNA decamer 5-dpCGC-TT-GCG-TT-3 was studied in solution by means of NMR spectroscopy and molecular dynamics in H2O. At a temperature of 269 K, a 50/50 mixture of two dumbbell structures (denoted L2L2 and L2L4) is present. The L2L2 form contains three Watson-Crick C-G base pairs and two two-residue loops in opposite parts of the molecule. On raising the temperature from 269 K to 314 K, the L2L4 conformer becomes increasingly dominant (95% at 314 K). This conformer has a partially disrupted G(anti)-C(syn) closing base pair in the 5-GTTC-3 loop with only one remaining (solvent-accessible) hydrogen bond between NH of the cytosine dC(1) and O6 of the guanine dG(8). The opposite 5-CTTG-3 loop remains stable. The two conformers occur in slow equilibrium (rate constant 2–20 s–1). Structure determination of the L2L2 and L2L4 forms was performed with the aid of a full relaxation matrix approach (IRMA) in combination with restrained MD. Torsional information was obtained from coupling constants. Coupling constant analysis (3JHH, 3JHP, 3JCP) gave detailed information about the local geometry around backbone torsion angles , , and , revealing a relatively high flexibility of the 5-GTTC-3 loop. The values of the coupling constants are virtually temperature-independent. Weakly constrained molecular dynamics in solvent was used to sample the conformational space of the dumbbell. The relaxation matrices from the MD simulation were averaged over r–3 to predict dynamic NOE volumes. In order to account for the 1:1 conformational mixture of L2L2 and L2L4 present at 271 K, we also included S2 factors and r–6 averaging of the r–3-averaged relaxation matrices. On matrix averaging, the agreement of NOE volumes with experiment improved significantly for protons located in the thermodynamically less stable 5-GTTC-3 loop. The difference in stability of the 5-CTTG-3 and 5-GTTC-3 loops is mainly caused by differences in the number of potential hydrogen bonds in the minor groove and differences in stacking overlap of the base pairs closing the minihairpin loops. The syn conformation for dC(1), favored at high temperature, is stabilized by solvation in the major groove. However, the conformational properties of the dC(1) base, as deduced from R-factor analysis and MD simulations, include a large flexibility about torsion angle . 相似文献
3.
Four radiolabled congeners of biphenyls with increasing chlorine content (biphenyl; 1-monochlorobiphenyl; 2,2,4,4-tetrachlorobiphenyl; and 2,2,4,4,5,5-hexachlorobiphenyl) were provided to suspension cultures of rose (Rosa sp. cv. Paul's Scarlet) for 4 days. Both the kinetics of 14C exchange between the cells and medium, and the metabolism of the parent compounds depended on the chlorine content of the congeners. Analysis of both the cells and their medium showed that of the recovered radioactivity 88%, 86%, and 3% of the biphenyl, 1-PCB, and 2,2,4,4-PCB were metabolized respectively to polar and insoluble residue products. The 2,2,4,4,5,5-PCB did not appear to be metabolized. 相似文献
4.
Fabián Atlasovich José A. Santomé Horacio N. Fernández 《Molecular and cellular biochemistry》1993,120(1):15-23
Summary Photoreactive probes for the hydrophobic pocket of the liver fatty acid-binding protein, 11-(5-azido-salicylamido)-undecanoic acid (5 ASU) and its acetyl ester (Ac5 ASU), were synthesized and their interaction with the protein was assessed. Fatty acid-binding proteins are closely related proteins which are abundantly expressed in tissues with active lipid metabolism. A simple model that assumes that the protein possesses a single kind of sites fitted the binding of radioiodinated 5 ASU to L-FABP satisfactorily. The apparent dissociation constant, 1.34×10–7 M, evidenced a slightly higher affinity than that reported for C16–C20 fatty acids. Consistent with the binding curve, 5 ASU effectively competed with palmitic acid for the hydrophobic sites and the effect was nearly complete for concentrations of 1 gmM; oleic acid, in turn, displaced the radiolabelled probe. Irradiation at 366 nm of125I-5 ASU bound to L-FABP caused the covalent cross-linking of the reagent. The amount of radioactivity covalently bound reached a maximum after 2 min thus agreeing with the photo-activation kinetics of the unlabelled compound that evidenced a t1/2 of 31.1 sec. The yield with which probes bound to L-FABP became covalently linked to the protein, appraised after SDS-PAGE of irradiated samples, was estimated as 23 and 26 per cent for 5 ASU and Ac5 ASU respectively. In turn, irradiation of L-FABP incubated with 5ASU or Ac5 ASU resulted in the irreversible loss of about one fourth its ability to bind palmitic acid. Both results, taken together, suggested that the derivatives are linked to the protein through the sites for fatty acids. When cross-linking of125I-5 ASU was performed after incubation with delipidated cytosol and products were analyzed by SDS-PAGE, a band was visualized in a position similar to that of purified L-FABP.Abbreviations FABP
Fatty Acid-Binding Protein
- L-FABP
Hepatic FABP
- I-FABP
Intestinal FABP
- C-FABP
Cardiac FABP
- 5 ASU-11
(5-azido-salicylamido)-undecanoic acid
- Ac5 ASU-11
(O-acetyl-5-azido-salicylamido)-undecanoic acid 相似文献
5.
Summary The actions of cyclic AMP are subject to several levels of post-receptor modulation in cardiac tissue. Isoproterenol and prostaglandin E1 both stimulate cAMP accumulation, but only isoproterenol causes activation of particulate cAMP-dependent protein kinase, leading to activation of phosphorylase kinase and glycogen phosphorylase, and inhibition of glycogen synthase. Through the use of isolated, adult ventricular myocytes, we have determined that the hormone-specific activation of glycogen phosphorylase is due to subcellular compartmentation of cAMP. There is some evidence that cyclic nucleotide phosphodiesterases, whose activity is stimulated by alpha1-adrenergic agonists in isolated myocytes, may have a role in compartmentation. Phosphoinositide hydrolysis is stimulated by alpha, and muscarinic agonists, presumably leading to activation of protein kinase C, which in turn has multiple effects on hormone-sensitive adenylate cyclase.Abbreviations cAMP
Adenosine-3,5-Cyclic Monophosphate
- cGMP
Guanosine-3,5-Cyclic Monophosphate
- Gi, GS
Guanine nucleotide-binding proteins linked to inhibition and stimulation, respectively, of adenylate cyclase
- GTP
Guanosine-5-triphosphate
- PDE
Cyclic Nucleotide Phosphodiesterase
- PGE1
Prostaglandin E1 相似文献
6.
S. Biagionia G. Scarsella L. Settimi M. E. Traina 《Molecular and cellular biochemistry》1982,43(3):183-190
Summary Inhibition of growth of PY815 mouse mastocytoma cells in vitro by N6, O2-dibutyryladenosine 3,5 cyclic monophosphate (DB cyclic AMP) was accompanied by increases in intracellular cyclic AMP and histamine and minor changes in cytosolic cyclic AMP-dependent histone kinase activity. However, DEAE-cellulose chromatography revealed substantial changes in the relative proportions of the principal cyclic AMP-dependent protein kinases and in free cyclic AMP-binding protein after DB cyclic AMP treatment. The activity of cytosolic cyclic AMP-dependent protein kinase type I (PKI) decreased relative to cyclic AMP-dependent protein kinase type II (PKII) and there was an increase in a cytosol cyclic AMP-binding protein with little associated protein kinase activity. The relative changes in activity of PKI, PKII and cyclic AMP binding protein after DB cyclic AMP treatment may reflect events important in the regulation of growth and differentiation of mast cells.Abbreviations DB cyclic AMP
N6,O2-dibutyryladenosine-3, 5-cyclic monophosphate
- cyclic AMP
adenosine 3,5-cyclic monophosphate
- PKI
type I cyclic AMP-dependent protein kinase
- PKII
type II cyclic AMP-dependent protein kinase 相似文献
7.
Internal pH (pHi) was determined inEmiliania huxleyi (Lohmann) using the probe 2,7-bis-(2-carboxyethyl)-5(and-6)carboxyfluoresceinacetoxymethylester (BCEF-AM) and digital imaging microscopy. The probe BCECF-AM was taken up and hydrolysed to the free acid by the cells. A linear relationship was established between pHi and the 490/450 fluorescence ratio of BCECF-AM over the pH range 6.0 to 8.0 using the ionophore nigericin. Two distinct pH domains were identified within the cell, the cytoplasmic domain (approx. pH 7.0) and the chloroplast domain (approx. pH 8.0). The average pHi was 7.29 (±0.11) for cells in the presence of 2 mM HCO
3
–
. In the absence of HCO
3
–
the pHi was decreased by 0.8 pH unit. The importance of these changes in pHi is considered in relation to inorganic-carbon uptake.Abbreviations AM
acetoxymethylester
- BCECF
2,7-bis-(2-carboxyethyl)-5(and-6)carboxyfluorescein
- Hepes
4-(2-hydroxyethyl)-1-piperazine ethanesulfonic acid
- pHi
intracellular pH 相似文献
8.
Irene M.A. Nooren Ke-Yu Wang Philip N. Borer István Pelczer 《Journal of biomolecular NMR》1998,11(3):319-328
The subject RNA models the binding site for the coat protein of the R17 virus, as well as the ribosome recognition sequence for the R17 replicase gene. With an RNA of this size, overlaps among the sugar protons complicate assignments of the 1H NMR spectrum. The cross peaks that overlap significantly in 2D-NOE spectra can frequently be resolved by introducing a third, in our approach the double-quantum, frequency axis. In particular the planes in a 3D-NOE/2QC spectrum perpendicular to the 2Q axis are extremely useful, showing a highly informative repeating NOE-2Q pattern. In this experiment substantial J-coupling confers special advantages. This always occurs for geminal pairs (H5/H5 for RNA plus H2/H2 for DNA), as well as for H5/H6, for H3/H4 in sugars with substantial populations of the N-pucker, for H1/H2 for S-puckered sugars, and usually for H2/H3. For the 24-mer RNA hairpin the additional information from the 3D-NOE/2QC spectrum allowed assignment of all of the non-exchangeable protons, eliminating the need for stable-isotope labeling. 相似文献
9.
Bennett T. Farmer II Luciano Müller Edward P. Nikonowicz Arthur Pardi 《Journal of biomolecular NMR》1994,4(1):129-133
Summary A set of three 3D (1H, 13C, 15N) triple-resonance correlation experiments has been designed to provide H1-H8 intraresidue sugar-to-base correlations in purines in an unambiguous and efficient manner. Together, the HsCsNb, HsCs(N)bCb, and HbNbCb experiments correlate the H1 sugar proton to the H8 proton of the attached base by means of the {H1, C1, N9, C8, H8} heteronuclear scalar coupling network. The assignment strategy presented here allows for unambiguous H1-H8 intraresidue correlations, provided that no two purines have both the same H1 and C1 chemical shifts and the same C8 and N9 chemical shifts. These experiments have yielded H1-H8 intraresidue sugar-to-base correlations for all five guanosines in the [13C, 15N] isotopically labeled RNA duplex r(GGCGCUUGCGUC)2. 相似文献
10.
The origin of Q-independent derivatives of phage lambda 总被引:13,自引:0,他引:13
Kim Kaiser 《Molecular & general genetics : MGG》1980,179(3):547-554
Summary qsr (Q-independent) phages are characterised by the replacement of the region of the genome that contains Q, S, R, and the late gene promoter, PR, with host-derived DNA that codes for functions analogous to those deleted. Restriction endonuclease analysis and DNA/DNA hybridisation methods have been used to show that p4 and qin A 3, two such Q-independent phages, are the product of recombination between and a defective lambdoid prophage (the qsr prophage) located at an as yet unidentified site in the E. coli K 12 chromosome. The qsr prophage is distinct from the defective lambdoid prophage Rac (Kaiser and Murray 1979). In the E. coli K 12 strain AB1157 from which qsr phages cannot be generated, the qsr prophage has suffered an internal deletion. That the qsr prophage appears not to carry a full complement of essential late genes suggests one explanation for its apparently defective nature. 相似文献
11.
The rate of CO2- and p-benzoquione-dependent photosynthetic O2 evolution by Anabaena variabilis cells remained unaltered and the rate of O2 uptake observed after switching off the light (endogenous respiration) was enhanced by a factor of 6–8 when the O2 concentration was increased from 200 to 400 M. Photosystem-I-linked O2 uptake and respiration of the cells incubated with ascorbate and N,N,NN-tetramethyl-p-phenylenediamine was not appreciable influenced by the O2 concentration. 2-Iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether, blocking electron transfer at the plastoquinone level, suppressed O2 evolution and had no influence on endogenous respiration. 2-n-Heptyl-4-hydroxyquinoline-N-oxide, an inhibitor of electron transfer between photosystems II and I, as well as the cytochrome-oxidase inhibitors N
3
-
, CN- and NH2OH, caused a 35–50% retardation of endogenous respiration and blocked photosynthetic O2 evolution. The molar ratio of cytochromes b6, f, c-553, aa3 and photosystem-I reaction centers in the isolated membranes equalled approx. 2:1:2:0.7:2. It is inferred that endogenous respiration of A. variabilis cells is inhibited by the light-induced electron flow through both photosystems at the level of the plastoquinone-plastocyanin-oxidoreductase complex.Abbreviations DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DNP-INT
2-iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether
- Hepes
4-(2-hydroxyethyl)-1-piperazine ethansulfonic acid
- TMPD
N,N,NN-tetramethyl-p-phenylenediamine 相似文献
12.
Summary 2-Amino-2-deoxyuridine reacts efficiently with nucleoside 5-phosphorimidazolides in aqueous solution. The dinucleoside monophosphate analogues were obtained in yields exceeding 80% under conditions in which little reaction occurs with the natural nucleosides.In a similar way, the 5-phosphorimidazolide of 2-amino-2-deoxyuridine undergoes self-condensation in aqueous solution to give a complex mixture of oligomers.The phosphoramidate bond in the dinucleoside monophosphate analogues is stable for several days at room temperature and pH 7. The mechanisms of their hydrolysis under acidic and alkaline conditions are described.Abbreviations A
adenosine
- C
cytidine
- G
guanosine
- U
uridine
- T
thymidine
- UN
3
2-azido-2-deoxyuridine
- UNH
2
2-amino-2-deoxyuridine
- ImpA
adenosine 5-phosphorimidazolide
- ImpU
uridine 5-phosphorimidazolide
- ImpUN
3
2-azido-2-deoxyuridine 5-phosphorimidazolide
- ImpUNH
2
2-amino-2-deoxyuridine 5-phosphorimidazolide
- pA
adenosine 5-phosphate
- pU
uridine 5-phosphate
- pUN
3
2-azido-2-deoxyuridine 5-phosphate
- pUNH
2
2-amino-2-deoxyuridine 5-phosphate
- UpA
uridylyl-[35]-adenosine
- UpU
uridylyl-[35]-uridine
- UNpA
adenylyl-[52]-2-amino-2-deoxy-uridine
- UNpU
uridylyl-[52]-2-amino-2-deoxyuridine (pUN)n n=2,3,4 [25]-linked oligomers of pUNH
2 poly(A) polyadenylic acid
- Im
imidazole
- MeIm
l-methylimidazole 相似文献
13.
Roots of spinach (Spinacia oleracea L.) seedlings contained only a very low activity of adenosine 5-phosphosulfate sulfotransferase compared to the cotyledons. Adenosine 5-phosphosulfate sulfotransferase activity increased about tenfold in cotyledons during greening. Preparation of organelle fractions from spinach leaves by a combination of differential and isopycnic density gradient centrifugation showed that adenosine 5-phosphosulfate sulfotransferase banded with NADP-glyceraldehyde-3-phosphate dehydrogenase, a marker enzyme for intact chloroplasts. In the fractions of peroxisomes, mitochondria and broken chloroplasts virtually no adenosine 5-phosphosulfate sulfotransferase activity was measured. Comparison with the chloroplast enzyme NADP-glyceraldehyde-3-phosphate dehydrogenase indicates that in spinach, adenosine 5-phosphosulfate sulfotransferase is localized almost exclusively in the chloroplasts.Abbreviations APS
Adenosine 5-phosphosulfate
- APSSTase
Adenosine 5-phosphosulfate sulfotransferase
- BSA
Bovine serum albumin
- BRIJ58
Polyethylene glycolmonostearylether
- DTE
Dithioerythritol
- DTT
Dithiothreitol
- EDTA
Ethylenediaminetetraacetic acid
- ME
2-Mercaptoethanol
- NADP-GPD
NADP-linked glyceraldehyde-3-phosphate dehydrogenase
- PAPS
Adenosine 3-phosphate 5-phosphate 5-phosphosulfate
- POPOP
1,4 Di [2-(5-phenyloxazolyl)]-benzene
- PPO
2,5-Diphenyloxazol
The results presented in this paper are taken from the Ph. D. thesis of H.F. 相似文献
14.
Frank Löhr Markus Blümel Jürgen M. Schmidt Heinz Rüterjans 《Journal of biomolecular NMR》1997,10(2):107-118
A triple-resonance NMR technique suitable for the determination ofcarbonyl-related couplings in polypeptide systems is introduced. Theapplication of three novel pulse sequences to uniformly13C/15N-enriched proteins yields E.COSY-likemultiplet patterns exhibiting either one of the3J(Ci–1,Hi
), 3J(Ci–1,Ci
) and3J(Ci–1,Ci)coupling constants in the indirectly detected 13Cdimension, depending on the passive spin selected. The experiments aredemonstrated with oxidized flavodoxin from Desulfovibrio vulgaris. On thebasis of the J-values measured and the backbone -angles derived from ahigh-resolution X-ray structure of the protein, the three associated Karplusequations were reparametrized. The root-mean-square differences between theexperimental coupling constants and those predicted by the optimized Karpluscurves are 0.41, 0.33 and 0.32 Hz for3J(Ci–1,Hi
),3J(Ci–1,Ci
) and3J(Ci–1,Ci),respectively. The results are compared with the Karplus parameters previouslypublished for the same couplings. 相似文献
15.
A quantitative analysis of JPH scalar couplings in nucleic acids is difficult due to small couplings to phosphorus, the extreme overlap of the sugar protons and the fast relaxation of the spins involved in the magnetization transfer. Here we present a new methodology that relies on heteronuclear Constant Time Correlation Spectroscopy (CT-COSY). The three vicinal 3JPH3, 3JPH5 and 3JPH5 scalar couplings can be obtained by monitoring the intensity decay of the Pi-H3i – 1 peak as a function of the constant time T in a 2D correlation map. The advantage of the new method resides in the possibility of measuring the two 3JPH5 and 3JPH5 scalar couplings even in the presence of overlapped H5/H5 resonances, since the quantitative information is extracted from the intensity decay of the P-H3 peak. Moreover, the relaxation of the H3 proton is considerably slower than that of the H5/H5 geminal protons and the commonly populated conformations of the phosphate backbone are associated with large 3JPH3 couplings and relatively small 3JPH5 / H5. These two facts lead to optimal signal-to-noise ratio for the P-H3 correlation compared to the P-H5/H5 correlation.The heteronuclear CT-COSY experiment is suitable for oligonucleotides in the 10–15 kDa molecular mass range and has been applied to the 30mer HIV-2 TAR RNA. The methodology presented here can be used to measure P-H dipolar couplings (DPH) as well. We will present qualitative results for the measurement of P-Hbase and P-H2 dipolar couplings in the HIV-2 TAR RNA and will discuss the reasons that so far precluded the quantification of the DPHs for the 30mer RNA. 相似文献
16.
Purification and properties of the ATP: adenylylsulphate 3′-phosphotransferase from Chlamydomonas reinhardii 总被引:3,自引:0,他引:3
APS-kinase (ATP: adenylylsulphate 3-phosphotransferase, EC 2.7.1.25) has been purified from the alga Chlamydomonas reinhardii, strain CW 15 by means of chromatofocussing and affinity chromatography. The isolated protein showed an apparent molecular mass of 44,000 upon sodium dodecylsulphate polyacrylamide gel electrophoresis. The transfer of phosphate groups from ATP onto APS required a pH of 6.8, the presence of Mg2+ ions and a reducing thiol. Its catalytical activity was destroyed by sulphhydryl group inhibitors (phenyl-mercuri compounds, dithiopyridine) and alkylating reagents.The purified enzyme attained a V
max of 360 pkat under optimal reaction conditions declining to v
limit of 260 pkat in the presence of excess substrate APS. This sensitivity towards changes in substrate concentrations was parallelled by a high affinity and specificity: apparent K
m APS: 2 · 10-6 mol · l-1, and K
m ATP: 7 · 10-6 mol · l-1. The enzyme was found specific for ATP, d-ATP and CTP, while UTP, ITP and GTP showed marginal activity. The Hill coefficients suggested 4 binding sites for APS and 1 for ATP. Excessive APS resulted in a negative slope indicating 3 inhibiting sites of the substrate.Abbreviations APS
Adenosine 5-phosphosulphate
- dATP
2-deoxyadenosine 5-triphosphate
- p-CMB
p-chloromercuribenzoate
- DTE
dithioerythritol
- DTT
dithiothreitol
- -MSH
-mercaptoethanol
- PAPS
3-phosphoadenosine 5-phosphosulphate
- PAP
3-phosphoadenosine 5-phosphate
- SDS
sodium dodecyl sulphate
This work is part of a dissertation submitted by H. G. J., Bochum 1982 相似文献
17.
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
18.
An efficient method of reduction of 3-azido-3-deoxythymidine and its 5-protected derivatives to 3-aminothymidine derivatives on a palladium catalyst using ammonium formate as a source of hydrogen was suggested.__________Translated from Bioorganicheskaya Khimiya, Vol. 31, No. 2, 2005, pp. 147–150.Original Russian Text Copyright © 2005 by Seregin, Chudinov, Yurkevich, Shvets. 相似文献
19.
Ahlert Schmidt 《Archives of microbiology》1977,112(3):263-270
Crude extracts of Rhodospirillum rubrum catalyzed the formation of acid-volatile radioactivity from (35S) sulfate, (35S) adenosine-5-phosphosulfate, and (35S) 3-phosphoadenosine-5-phosphosulfate. An enzyme fraction similar to APS-sulfotransferases from plant sources was purified 228-fold from Rhodospirillum rubrum. It is suggested here that this enzyme is specific for adenosine-5-phosphosulfate, because the purified enzyme fraction metabolized adenosine-5-phosphosulfate, however, only at a rate of 1/10 of that with adenosine-5-phosphosulfate. Further, the reaction with 3-phosphoadenosine-5-phosphosulfate was inhibited with 3-phosphoadenosine-5-phosphate whereas this nucleotide had no effect on the reaction with adenosine-5-phosphosulfate. For this activity with adenosine-5-phosphosulfate the name APS-sulfotransferase is suggested. This APS-sulfotransferase needs thiols for activity; good rates were obtained with either dithioerythritol or reduced glutathione; other thiols like cysteine, 2-3-dimercaptopropanol or mercaptoethanol are less effective. The electron donor methylviologen did not catalyze this reaction. The pH-optimum was about 9.0; the apparent K
m for adenosine-5-phosphosulfate was determined to be 0.05 mM with this so far purified enzyme fraction. Enzyme activity was increased with K2SO4 and Na2SO4 and was inhibited by 5-AMP. These properties are similar to assimilatory APS-sulfotransferases from spinach and Chlorella.Abbreviations APS
adenosine-5-phosphosulfate
- PAPS
3-phosphoadenosine-5-phosphosulfate
- 5-AMP
adenosine-5-monophosphate
- 3-AMP
adenosine-3-monophosphate
- 3-5-ADP
3-phosphoadenosine-5-phosphate (PAP)
- DTE
dithiorythritol
- GSH
reduced glutathione
- BAL
2-3-dimercaptopropanol 相似文献
20.
Summary The aminoacyl-tRNA synthetases play a dual role in cell metabolism by synthesizing aminoacyl-tRNAs and an odd dinucleotide diadenosine-5, 5-P1, P4-tetraphosphate which appears to be involved in DNA replication and the control of cell proliferation. This review is a synthesis of recent results on the structure, genetics, cell biology, physiology, role in neoplasia, and role in autoimmune myositis of the higher eukaryotic aminoacyl-tRNA synthetases. 相似文献