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1.
Complexes of the formula cis-[Pt(H~N)(L)Cl2], where (H~N) are the protonated diamines including 3-aminoquinuclidine, N-aminopiperidine, piperazine, N-methylpiperazine, 1,1,4-trimethylpiperazine, and N-methyl-1,4-diazabicyclo [2,2,2] octane (N-methyl-dabco) and L = SCN?, NO2?, Br?, and F?, were synthesized from the protonated diamine complexes, [Pt(H~N)Cl3]. The antitumor activities of the complexes were evaluated in vitro against L1210 murine leukemia cells, and ID50 values for the L-substituted complexes were compared to values of the parent complexes. In each case it was found that replacement of a chloride ion by SCN?, NO2?, Br?, or F?, either reduced or completely eliminated antitumor activity. This effect is explained in terms of the trans-directing ability of the ligand, L, compared to chloride. The NO2-substituted complex of 3- aminoquinuclidine was tested in vivo and found to exhibit little or no antitumor activity. 相似文献
2.
Sun-Shine Yuan 《Steroids》1982,39(3):279-289
A-ring enollactones , or derived from 4-cholesten-3-one, testosterone benzoate or 3-oxo-4-estren-17β-yl benzoate were condensed with [1,2-13C2]acetyl chloride to give intermediates , or . and were cyclized by acid or base to give 3,4-13C2-labeled 4-cholesten-3-one and testosterone, respectively. [3,4-13C2]4-Cholesten-3-one was converted via reduction of its trimethylsilyl enol ether to [3,4-13C2]cholesterol. Acetyl enollactone was cyclized in acetic acid to [3,4-13C2]3-oxo-4-estren-17β-yl benzoate followed by aromatization and hydrolysis to produce [3,4-13C2]estradiol-17β. Alternatively, cyclization of with base afforded [3,4-13C2]3-oxo-4-estren-17β-ol directly, which was then oxidized and aromatized to yield [3,4-13C2]estrone. Ozonolysis of progesterone, conversion to the diketal ester and acylation followed by acid hydrolysis furnished [3,4-13C2]progesterone. 相似文献
3.
Unidirectional fluxes of [14C]lactose by whole cells of Escherichia coli under highly energized and partially de-energized (in the presence of CN?) conditions are analyzed kinetically.When the cells are energized, the value for influx is internal concentration increment/s and is . At an external concentration of 0.61 mM the steady-state internal concentration is 0.25 M, reached after about 1h. The maximum steady-state concentration ratio is .The efflux process under these conditions is non-saturable, being linearly dependent upon internal concentration over the range 25–250 mM with a first-order rate constant of .The transport in the presence of CN? is active, with a maximum concentration ratio (internal concentration/external concentration) of 104, and the uptake is mimicked by anoxia (< 70 ppm O2).The effects of CN? are to lower the for influx and to change the efflux from a non-saturable to a saturable process with a value for (60 mM) intermediate between that for energized efflux () and influxe (0.3–0.6 mM), the latter value not changing appreciably. Partial de-energization thus affects both the influx and efflux processes. 相似文献
4.
The mineral helvite, (Mn4S)(BeSiO4)3, contains discrete tetrahedral Mn4S+6 clusters in which the S?2 is tetrahedrally coordinated and each Mn(II) is in a distorted tetrahedron of one S?2 and three oxygens; the cluster is situated within an encompassing lattice of SiO4?4 and BeO4?6 tetrahedra. Mn4S+6 centers provide an interesting model for comparison to the polynuclear manganese center that is associated with photosynthetic water oxidation. Magnetic susceptibility data between 77 and 298 K have been measured for a natural helvite sample containing principally Mn4S+6 centers but with significant contamination from Mn3FeS+6 and Mn3CaS+6. The data exhibited Curie-Weiss behavior with μeff = 5.969 B.M. and θ = 178.3 K. An analysis of the magnetic susceptibility, based on Van Vleck's formalism, demonstrated the presence of antiferromagnetic coupling, with a coupling constant J = ?5.83 cm?1. Mössbauer spectra of Mn3FeS centers in helvite and of Fe4S centers in the related mineral danalite have also been recorded. Isomer shifts show little temperature dependence and lie in the range 1.23–1.43 . This range is typical of tetrahedrally coordinated Fe(II) in several ionic crystals but is significantly above that of Fe(II) in ferredoxins and below that in the [quinone-Fe(II)-quinone] complex of the photosynthetic bacterium,Rhodopseudomonas sphaeroides. Quadrupole splittings are highly temperature dependent, ranging from 2.4 at 4.2 K to less than 0.5 at 248 K. 相似文献
5.
Jean-Pierre Girault Jean-Claude Chottard Eric R. Guittet Jean-Yves Lallemand Tam Huynh-Dinh Jean Igolen 《Biochemical and biophysical research communications》1982,109(4):1157-1163
The stoichiometric reaction between d-TpGpGpCpCpA (d(T-G-G-C-C-A)) and -[Pt(NH3)2(H2O)2](NO3)2 (8.4 × 10?6 to 1.3 × 10?4M in water at pH 5.5–6) gives a single complex. High pressure gel permeation chromatography and pH-dependent 1H NMR analyses of the nonexchangeable base protons, show that it is a platinum chelate with the -PtII(NH3)2 moiety bound to the two N7 atoms of the adjacent guanines. A 3 × 10?3M reaction gives the same platinum chelate, via the formation of intermediate complexes, together with unsoluble adducts. 相似文献
6.
The effects of endometrium on metabolism of [3H]-arachidonic acid ([3H]-AA) by bovine blastocysts recovered on day 19 postmating were studied . Blastocysts (n = 12) and endometrial slices were assigned to four incubation groups. In group 1, blastocysts were incubated alone; group 2, endometrial slices were incubated alone; group 3, blastocysts were incubated with endometrial slices; group 4, blastocysts were incubated in 7.5 ml fresh incubation medium plus 7.5 ml frozen-thawed medium from endometrial incubations. In all groups, tissues were incubated in 15 ml modified minimum essential medium (MEM) containing 5 μCi of [3H]-AA and 200 μg radioinert arachidonic acid for 24 h at 37°C in an atmosphere of 50% N2:45% O2:5% CO2. For incubation controls, 5 μCi of [3H]-AA were added to 15 ml MEM and incubated at the same time as tissues from each cow. To evaluate metabolism of [3H]-AA, [3H]-AA and its metabolites were extracted from aliquots of MEM and separated on columns of Sephadex LH-20. Most (78.3 ± 3.2%) of the radioactivity (dpm) in the incubation controls was recovered as [3H]-AA, indicating that there was little breakdown of [3H]-AA in the absence of tissue. Blastocysts produced compounds that migrated with [3H]-13,14-dihydro-15-keto-PGF2α ([2H]-PGFM), [3H]-PGE2 and [3H]-PGF2α. Endometrial slices metabolized very little of the [3H]-AA. Data from groups 1 and 4 were combined (group ) for analysis because the distribution of dpm did not differ between the two groups. In group 3, blastocysts and endometrial slices incubated together tended(P<.10) to produced more [3H]-PGE2 than did group , there tended to be less (P<.10)_[3H]-PGF2α, and there was more (P<.05) [3H]-PGFM than in group . Neither endometrial secretions nor endometrial slices altered the proportion of [3H]-AA metabolized by blastocysts. Endometrial slices appear capable of metabolizing [3H]-PGF2α synthesized by blastocysts, and capable of directing blastocyst metabolism of [3H]-AA away from synthesis of [3H]-PGF2α and toward synthesis of [3H]-PGE2. It is postulated that the endometrium has an important role in regulating the amounts and ratios of prostaglandins in th uterine lumen during early prenancy in cows. 相似文献
7.
Membrane vesicles from pigeon erythrocytes show a rapid, ATP-dependent accumulation of 45Ca2+. Ca2+ accumulation ratios greater than or approximately equal to 104 are readily attained. For ATP-dependent Ca2+ uptake, V is 1.5 mmol · 1?1 · min?1 at 27°C (approx. 0.9 nmol · mg?1 protein · min?1), [Ca2+] is 0.18 μM, [ATP] is 30–60 μM, the Ca2+ uptake rate depends on [Ca2+]2 and the dependence of uptake rate on ATP concentration implies strong ATP-ATP cooperativity. The Arrhenius activation energy is 19.1 ± 1.4 kcal/mol and the pH optimum is approx. 6.9. 相似文献
8.
D.John Aberhart 《Bioorganic chemistry》1977,6(2):191-201
Ammonium[2-3H,1-14C]isobutyrate was converted by Pseudomonas putida ATCC 21244 into S(+)-β-hydroxyisobutyric acid (β-HIBA) with loss of the α-tritium atom. The recovered isobutyrate had the same as the starting material. Ammonium (2S)-[3-13C]isobutyrate was synthesized and converted by P. putida into β-HIBA. The 13C-nmr of the corresponding methyl ester benzoate showed 13C enrichment in the hydroxymethyl carbon atom. The results therefore indicate that isobutyrate metabolism in this organism proceeds via an unsaturated intermediate (probably methacrylyl-CoA) formed by dehydrogenation of the 2-pro-S-methyl group of the precursor (isobutyryl-CoA). Hydration of the intermediate proceeds with addition of a proton at C-2 from the same side as the hydrogen removed in the dehydrogenation. 相似文献
9.
[3H]Flunitrazepam was used to characterize benzodiazepine binding sites in human brain. The benzodiazepine binding sites exhibited high affinity, pharmacological specificity and saturability in their binding of [3H]flunitrazepam. The dissociation constant (KD) of [3H]flunitrazepam binding was determined by three different methods and found to be in the range of 2–3 nM. The potency of several benzodiazepine analogs to inhibit specific [3H]-flunitrazepam binding correlated well with their potency in several human and animal tests. The density of [3H]-flunitrazepam binding sites was highest in the cerebrocortical and rhinencephalic areas, intermediate in the cerebellum, and lowest in the brain stem and commissural tracts. 相似文献
10.
G Litwack R Filler S Rosenfield N Lichtash 《Biochemical and biophysical research communications》1973,55(3):977-984
[3H] Prostaglandin E1 (PGE1) is bound extensively to macromolecules in liver cytosol . A principal binding protein accounts for 80% of the binding. This macromolecule is saturated at about 10?10 M PGE1. The partially purified protein has a molecular weight of 50,000 by gel filtration and a pI of about 3.5 by isoelectrofocusing. Binding is primarily noncovalent and the dissociated ligand behaves similarly to the parental [3H] PGE1 on thin layer chromatography. Possible significance of this interaction is discussed. 相似文献
11.
Four assay methods were tested for the measurement of Δ1-piperideine-2-carboxylate, a proposed alicyclic ketimino acid intermediate in the pathway of lysine metabolism to l-pipecolate, and the product of d-amino acid oxidase on d-pipecolate. The method using Δ1-piperideine-2-carboxylate reductase from Pseudomonas putida was found to be most sensitive and specific. Measurement of Δ1-piperideine-2-carboxylate by reduction with NaBH4 and ninhydrin assay of the resultant pipecolate, by direct acidic ninhydrin assay, and by o-aminobenz-aldehyde assay were less desirable because of lower sensitivity and specificity. Two synthetic methods for preparing l-[14C]pipecolate from the racemic dl-[14C]pipecolate were investigated. Incubation of dl-[14C]pipecolate with a combination of d-amino acid oxidase and Δ1-piperideine-2-carboxylate reductase or d-amino acid oxidase and NaBH4 totally inverted the d-isomer to the l-isomer, with as an intermediate in each cycle of interconversion. No purification except desalting through a Dowex 50 (H+) column was necessary in order to recover l-[14C]pipecolate in pure form. The yield was 95–97% compared to <50% in the conventional method. 相似文献
12.
Agneta Nordberg 《Life sciences》1978,23(9):937-944
Kinetic parameters for high affinity [HA] uptake in synaptosomes from different mouse brain regions were investigated. Vmax was highest in the striatum [200 pmol.· mg protein?1 · 4 min?1], followed by the cortex [111 pmol · mg protein?1 · 4 min?1], hippocampus [63 pmol · mg protein?1 · 4 min?1], midbrain [21 pmol · mg protein?1 · 4 min?1] and, lowest, medulla oblongata [5 pmol · mg protein?1 · 4 min?1]. Km was about the same in all brain regions [0.9–1.4 μM]. No sign of HA uptake was detected in synaptosomes from the cerebellum. A clear relationship between Vmax for synaptosomal HA uptake of Ch and apparent turnover of ACh was found between the brain regions. Administration of oxotremorine [1 mg·kg?1 i.p.] decreased Vmax for HA uptake of Ch by 60% in the cortex and hippocampus, by 50% in the striatum and by 20% in the midbrain. This effect is in accordance with the previously observed marked decrease in turnover of ACh in these brain regions following oxotremorine treatment. 相似文献
13.
Luis O. Rodriguez Sidney M. Hecht 《Biochemical and biophysical research communications》1982,104(4):1470-1476
Consistent with a recent literature report (Repine, J. E. (1981) , 1001–1003), the release of [3H]-thymine from PM-2 DNA by Fe(II)-H2O2-generated ·OH was suppressed by dimethyl sulfoxide. In contrast, DMSO did not affect [3H]-thymine release mediated by Fe(II)-bleomycin. Under aerobic conditions in the presence of -butyl phenylnitrone, Fe(II)-BLM produces an epr signal that has been presumed to arise by transfer of ·OH or from the “active complex” of bleomycin to the spin trap. Remarkably, high concentrations (80 mM) of PBN had no effect on the ability of Fe(II)-BLM to solubilize [3H]-thymine, although the ability of authentic ·OH to degrade DNA was completely suppressed under these condition. The suproxide dismutase catalyst tetrakis(4-N-methylpyridyl)porphineiron(III) also failed to suppress BLM-mediated DNA degradation. Moreover, the epr signal observed with 1.6 mM Fe(II)-BLM in the presence of 80 mM PBN was found to be much less intense than that produced by 1.6 mM Fe(II) and 290 mM H2O2, but equivalent in intensity to that obtained with 45 mM Fe(II) and exoess H2O2. We conclude that the fragmentation of DNA produced by Fe(II)-BLM can be due neither to free ·OH nor to . We suggest that DNA degradation is initiated by an “active complex” consisting of BLM, metal and oxygen that functions by abstracting H· from susceptible sites on DNA. 相似文献
14.
C Hedgcoth K Thomas K Scheets S Allen 《Biochemical and biophysical research communications》1980,95(2):880-886
When murine sarcoma virus-transformed cells are labeled with [3H]lysine for various periods, 5 of 6 isoaccepting lysine tRNAs separable by RPC-5 chromatography are aminoacylated in 1 hr to the same extent that they are aminoacylated . The sixth isoacceptor, tRNA6Lys, is not aminoacylated to a measurable extent in 1 hr, although it is present in the tRNA prepared from the cells. All six isoacceptors are aminoacylated with [3H]lysine when the labeling period is 2 or 3 hr. These results further show that correlations of the amount of tRNA4Lys with cell division accurately reflect the situation . Results of differential centrifugation indicate that tRNA6Lys occurs in mitochondria. 相似文献
15.
The kinetics of methemoglobin reduction by Fe(EDTA)2? have been studied and found to follow a second order rate law with k = 29.0 ?1 s?1 [25°C, μ = 0.2 , pH 7.0 (phosphate)], , and . The electrostatics-corrected self-exchange rate constant (k11corr) for hemoglobin based on the Fe(EDTA)2? cross-reaction is 2.79×10?3?1 s?1. This rate constant is compared with others reported for a water-soluble iron porphyrin and calculated from published data for the reactions of myoglobin and hemoglobin with Fe(EDTA)2? and Fe(CDTA)2?/?. The k11corr values for these systems range over ten orders of magnitude with heme ? myoglobin > hemoglobin. 相似文献
16.
Robert Presswood J.W. Hastings 《Biochemical and biophysical research communications》1978,82(3):990-996
Upon reaction of luciferase-FMNH2 with oxygen a complex series of absorbance changes occur, leading to the formation of a stable ( about 35 min at 2°) dihydroflavin peroxyluciferase intermediate. Observed at 380, 445, or 600 nm, there is first a rapid absorbance increase which is oxygen-concentration dependent (k ? 106 M?1s?1. Following this there are two oxygen independent steps, first a slow absorbance decrease (k = 4.3 s?1) and then an even slower increase (k = 0.55 s?1). The dihydroflavin peroxide is not expected to have absorption at 600 nm and is thus postulated to be in equilibrium with some flavin species which does absorb in the red. 相似文献
17.
[3H] quinuclidinyl benzilate (QNB), a specific muscarinic antagonist, was utilized to identify muscarinic cholinergic receptors on dispersed anterior pituitary cells. Scatchard analysis of [3H] QNB binding to receptors departs from linearity with upward concavity. A high affinity binding site having a dissociation constant (Kd) of 1.5 nM was observed when the [3H] QNB concentration was varied from 0.15 to 20 nM. A low affinity binding site (Kd 20 nM) was observed when [3H] QNB concentration was above 20 nM. Using 10 nM [3H] QNB for binding, the second order association rate constant (k1) of 0.064 nM?1 min?1 and first order dissociation rate constant (k2) of 0.078 min?1 were observed. k2/k1 = Kd of 1.22 nM is in good agreement with Kd = 1.5 nM from equilibrium data. Muscarinic cholinergic receptor antagonists, atropine and scopolamine, and agonist oxtoremorine potently competed with [3H] QNB binding. A nicotinic cholinergic receptor agonist was 50 times less potent as a competitor of [3H] QNB binding than the muscarinic agonist. 相似文献
18.
Robert E. Lynch Barry C. Cole 《Biochemical and biophysical research communications》1980,96(1):98-105
Superoxide dismutase and catalase were not detected in . and several other species of some of which consume oxygen and secrete H2O2. . in suspension formed O2? in the presence of NADH and flavins and extracts of . formed O2? in the presence of either NADH or NADPH. The lack of superoxide dismutase in . could not be attributed to superoxide dismutase in the complex medium in which the organisms were grown because organisms grown in medium in which the superoxide dismutase had been inactivated by heat still contained undetectable amounts. Mycoplasmas appear to be an exception to the rule that organisms which consume O2 synthesize superoxide dismutase. 相似文献
19.
Properties of [3H]diazepam binding sites on rat blood platelets 总被引:8,自引:0,他引:8
Intact rat blood platelets are shown to possess benzodiazepine binding sites of the peripheral type, binding of [3H]diazepam being strongly inhibited by Ro5-4864 (Ki = 3.6 ± 0.5 nM) but only weakly inhibited by clonazepam (Ki = 35.1 ± 18.2 μM). Binding of [3H]diazepam is specific and saturable. Scatchard analysis reveals a single class of binding sites with KD = 14.7 ± 1.0 nM and Bmax = 564 ± 75 fmoles/108 platelets. The Hill coefficient is 0.94, indicating a lack of binding site heterogeneity or negative cooperativity. Binding reaches equiliibrium at 6 min, with k+1 = 2.9 × 107 M?1 min?1, and is rapidly reversible ( with K?1 = 0.315 min?1. KD derived from the rate constants agrees with that estimated by Scatchard analysis. KD of the crude membrane fraction of platelets is also close to that of intact platelets. Binding of [3H]diazepam is linear with platelet number (between 0.25–2 × 108 platelets), is temperature sensitive with maximum binding at 0°C, and has a broad optimal pH range between pH 5–9. 相似文献
20.
The cell-free preparations from autotrophieally grown Pseudomonas saccharophila catalyzed the process of electron transport from H2 or various other organic electron donors to either O2 or NO3? with concomitant ATP generation. The respective ratios with H2 and NADH were 0.63 and 0.73, the respective ratios were 0.57 and 0.54. In contrast, the and ratios with succinate were 0.18 and 0.11, respectively. ATP formation coupled to the oxidation of ascorbate, in the absence or presence of added N,N,N′,N′-tetramethyl-p-phenylenediamine or cytochrome c, could not be detected. Various uncouplers inhibited phosphorylation with either O2 or NO3? as terminal electron acceptors without affecting the oxidation of H2 or other substrates. The NADH oxidation at the expense of O2 or NO3? reduction as well as the associated phosphorylation were inhibited by rotenone and amytal. The aerobic and anaerobic H2 oxidation and coupled ATP synthesis, on the other hand, was unaffected by the flavoprotein inhibitors as well as by the NADH trapping system. The NADH, H2, and succinate-linked electron transport to O2 or NO3? and the associated phosphorylations were sensitive, however, to antimycin A or 2-n-nonyl-4-hydroxyquino-line-N-oxide, and cyanide or azide. The data indicated that although the phosphorylation sites 1 and II were associated with NADH oxidation by O2 or NO3?, the energy conservation coupled to H2 oxidation under aerobic or anaerobic conditions appeared to involve site II only. 相似文献