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1.
Gibberellin A 1 (GA 1), which was identified as the major GA from the GA-producing fungus Phaeosphaeria sp. L487, was accumulated in the culture with a maltose-yeast extract medium, its amount in the culture filtrate being about 50 mg per liter after a 3-week culture. The new fungal biosynthetic pathway to GA 1 from GA 9 via GA 4 was elucidated by feeding experiments with synthetic [17- 2H 2]GA 9 and [17- 2H 2]GA 4. 相似文献
2.
The localization of tritium-radioactivity in dwarf kidney bean plants ( Phaseolus vulgaris) of 3H-gibberellm A 3( 3H-GA 3) applied in a large quantity was investigated in advance of the study on GA 3 metabolism in this plant. Immediately after the application of 3H-GA 3, the radioactivity was distributed uniformly in the top of this plant; no further transportation of the radioactivity into the growing apical region from mature leaves and stems was the observed as the growth stage proceeded. An investigation on the intracellular localization of the radioactivity demonstrated that most part of the radioactivity was found in the cellular soluble fraction, while no radioactivity was detected in such subcellular particles as nuclei, mitochondria and microsomes. Examinations of the occurrence of GA 3 bound with such macromolecules as RNA and protein gave negative results. 相似文献
3.
The structures of two gibberellin-like substances isolated from the immature seeds of Prunus persica, tentatively named PG–I and PG–II, were elucidated. PG–I was an ammonium salt of a novel gibberellin, ent-3α,10,12β,13,15α-pentahydroxy-20-norgibberella-l,16-diene-7,19-dioic-19,10-lactone (1), to which gibberellin number A 32 was allocated. PG–II was shown to be gibberellin A 32 acetonide (7), and concluded to be an artifact produced from gibberellin A 32 in the isolation process. 相似文献
4.
New 7-amino-2-phenylpyrazolo[4,3- d]pyrimidine derivatives, substituted at the 5-position with aryl(alkyl)amino- and 4-substituted-piperazin-1-yl- moieties, were synthesized with the aim of targeting human (h) adenosine A 1 and/or A 2A receptor subtypes. On the whole, the novel derivatives 1– 24 shared scarce or no affinities for the off-target hA 2B and hA 3 ARs. The 5-(4-hydroxyphenethylamino)- derivative 12 showed both good affinity ( Ki =?150?nM) and the best selectivity for the hA 2A AR while the 5-benzylamino-substituted 5 displayed the best combined hA 2A ( Ki =?123?nM) and A 1 AR affinity ( Ki =?25?nM). The 5-phenethylamino moiety (compound 6) achieved nanomolar affinity ( Ki =?11?nM) and good selectivity for the hA 1 AR. The 5-(N 4-substituted-piperazin-1-yl) derivatives 15– 24 bind the hA 1 AR subtype with affinities falling in the high nanomolar range. A structure-based molecular modeling study was conducted to rationalize the experimental binding data from a molecular point of view using both molecular docking studies and Interaction Energy Fingerprints (IEFs) analysis. 相似文献
5.
[17- 13C, 3H]-Labeled gibberellin A 20 (GA 20), GA 5, and GA 1 were fed to homozygous normal (+/+), heterozygous dominant dwarf ( D8/+), and homozygous dominant dwarf ( D8/D8) seedlings of Zea mays L. (maize). 13C-Labeled GA 29, GA 8, GA 5, GA 1, and 3-epi-GA 1, as well as unmetabolized [ 13C]GA 20, were identified by gas chromatography-selected ion monitoring (GC-SIM) from feeds of [17- 13C, 3H]GA 20 to all three genotypes. 13C-Labeled GA 8 and 3-epi-G 1, as well as unmetabolized [ 13C]GA 1, were identified by GC-SIM from feeds of [17- 13C, 3H]GA 1 to all three genotypes. From feeds of [17- 13C, 3H]GA 5, 13C-labeled GA 3 and the GA 3-isolactone, as well as unmetabolized [ 13C]GA 5, were identified by GC-SIM from +/+ and D8/D8, and by full scan GC-MS from D8/+. No evidence was found for the metabolism of [17- 13C, 3H]GA 5 to [ 13C]GA 1, either by full scan GC-mass spectrometry or by GC-SIM. The results demonstrate the presence in maize seedlings of three separate branches from GA 20, as follows: (a) GA 20 → GA 1 → GA 8; (b) GA 20 → GA 5 → GA 3; and (c) GA 20 → GA 29. The in vivo biogenesis of GA 3 from GA 5, as well as the origin of GA 5 from GA 20, are conclusively established for the first time in a higher plant (maize shoots). 相似文献
6.
On the basis of potent and selective binding affinity of Cl-IB-MECA to the human A 3 adenosine receptor, its 4′-thioadenosine derivatives were efficiently synthesized starting from D-gulonic γ -lactone. Among compounds tested, 2-chloro- N 6-(3-iodobenzyl)- and 2-chloro- N 6-methyl-4′ -thioadenosine-5′ -methyluronamides ( 7a and 7b) exhibited nanomolar range of binding affinity ( K i = 0.38 nM and 0.28 nM, respectively) at the human A 3AR. These compounds showed anti-growth effects on HL-60 leukemia cell, which resulted from the inhibition of Wnt signaling pathway. 相似文献
7.
Gibberellin A 5 (GA 5), a native GA of immature seeds of Pharbitis nil, was fed to Pharbitis nil cell suspension cultures as [C-l, 3H] GA 5 (3.1 Ci/mmol), and its metabolism over a 48 hr period was investigated. Radioactivity in free GA metabolites was 13.1%, with 79.9% in GA glucosyl conjugate-like metabolites. Only 7.0% of the radioactivity remained as [ 3H] GA 5. Tentative identifications were based on comparison with retention times of authentic free GAs and/or glucosyl conjugates after sequential chromatography on Si gel partition column → gradient-eluted C18 HPLC-radiocounting (RC) → isocratic-eluted C18 HPLC-RC, and showed that [ 3H] GA 5 was converted to [ 3H] GA 1 (2%), [ 3H] GA 3 (4%), [ 3H] GA 6 (2%), [ 3H] GA 22 (1%) and their glucosyl conjugates, and also to [ 3H] GA 8 glucoside, and [ 3H] GA 5 glucosyl conjugates. The major conjugate-like substances were [ 3H] GA 1 and [ 3H] GA 3 glucosyl esters, at 15% and 34%, respectively, of the total extractable radioactivity. 相似文献
8.
Abstract Various adenosine analogues were tested at the adenosine A 2B receptor. Agonist potencies were determined by measuring the cyclic AMP production in Chinese Hamster Ovary cells expressing human A 2B receptors. 5′-.N-Substituted carboxamidoadenosines were most potent. 5′-N-Ethylcarboxamidoadenosine (NECA) was most active with an ECso value of 3.1 μM. Other ribose modified derivatives displayed low to negligible activity. Potency was reduced by substitution on the exocyclic amino function (N 6) of the purine ring system. The most active N 6-substituted derivative N 6-methyl-NECA was 5 fold less potent than NECA. C8-and most C2-substituted analogues were virtually inactive. 1-Deaza-analogues had a reduced potency, 3-and 7-deazaanalogues were not active. 相似文献
9.
Previously, we have reported that the coronary reactive hyperemic response was reduced in adenosine A2A receptor-null (A2AAR?/?) mice, and it was reversed by the soluble epoxide hydrolase (sEH) inhibitor. However, it is unknown in aortic vascular response, therefore, we hypothesized that A2AAR-gene deletion in mice (A2AAR?/?) affects adenosine-induced vascular response by increase in sEH and adenosine A1 receptor (A1AR) activities. A2AAR?/? mice showed an increase in sEH, AI AR and CYP450-4A protein expression but decrease in CYP450-2C compared to C57Bl/6 mice. NECA (adenosine-analog) and CCPA (adenosine A1 receptor-agonist)-induced dose-dependent vascular response was tested with t-AUCB (sEH-inhibitor) and angiotensin-II (Ang-II) in A2AAR?/? vs. C57Bl/6 mice. In A2AAR?/?, NECA and CCPA-induced increase in dose-dependent vasoconstriction compared to C57Bl/6 mice. However, NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? was reduced by t-AUCB with NECA. Similarly, dose-dependent vascular contraction in A2AAR?/? was reduced by t-AUCB with CCPA. In addition, Ang-II enhanced NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? with NECA. Similarly, the dose-dependent vascular contraction in A2AAR?/? was also enhanced by Ang-II with CCPA. Further, t-AUCB reduced Ang-II-enhanced NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? mice. Our data suggest that the dose-dependent vascular contraction in A2AAR?/? mice depends on increase in sEH, A1AR and CYP4A protein expression. 相似文献
10.
Abstract Adenosine derivatives bearing in 2-position the ( R, S)- phenylhydroxypropynyl chain were evaluated for their potency at human A 2B adenosine receptor, stably transfected on CHO cells, on the basis that ( R, S)-2-phenylhydroxy-propynyl-5′-N-ethylcarboxyamidoadenosine [( R, S)-PHPNECA] was found to be a good agonist at the A 2B receptor subtype. Biological studies demonstrated that the presence of small alkyl groups in N 6-position of these molecules are well tolerated, whereas large groups abolished A 2B potency. On the other hand, the presence of an ethyl group in the 4′-carboxamido function seems to be optimal, the ( S)-PHPNECA resulting the most potent agonist at A 2B receptor reported so far. 相似文献
11.
In Hermissenda type-B photoreceptors, the spike is generated in the axon and back-propagated to the soma, resulting in smaller somatic spikes.
Experimentally, blocking the A-type K + current ( IK,A) results in broadening of somatic spikes. Similarly, in a compartmental model of the photoreceptor, reducing the maximum
A-type K + conductance ( gK,Amax) results in broadening of somatic spikes. However, simulations predict that little or no broadening of axonal spikes occurs
when gK,Amax is reduced. The results can be explained by the voltage-dependent properties of IK,A and the different potential ranges that the somatic and axonal spike traverse. Because of the steeper I-V curve and faster activation of the K + channels at higher potentials, the recruitment of additional K + channels in the axon is able to compensate for the decrease in K + conductance, yielding less spike broadening. These results also support the idea that spike duration in the axon may not
be reliably inferred based upon recordings collected from the soma.
Action Editor: Jonathan D. Victor 相似文献
12.
The structures of three new gibberellins A 30, A 48 and A 49 and a new kaurenolide, isolated from seeds of Cucurbita pepo L., were elucidated. The structures of GA 39, GA 48 and GA 49 were shown to be ent-3α,12 β-dihydroxygibberell-16-ene-7,19,20-trioic acid ( 1), ent-2α,3α,10,12α-tetrahydroxy-20-norgibberell-16-ene-7,19-dioic acid 19,10-lactone ( 5) and the epimer at C–12 of GA 48 ( 8), respectively. The kaurenolide was shown to have the structure: ent-6 β,7α,12 β-trihydroxykaur-16-en-19-oic acid 19,6-lactone ( 14). 相似文献
13.
Two aldehydic C 20-gibberellins, L-2 and L-4, were isolated from the immature fruits of yellow lupine ( Lupinus luteus L.). L-2 was shown to have the structure II and named gibberellin A 23. L-4 was identified as gibberellin A 19(VI). Two new C 20-gibberellins, tentatively called 3,13-dihydroxy GA 15(IV) and 13-hydroxy GA 15(VIII), were derived from gibberellins, A 23 and A 19, respectively. The biological activities of four 3,13-dihydroxy C 20-gibberellins-GA 18(I), GA 23(II), GA 28(III) and 3,13-dihydroxy GA 15(IV), which were isolated from the fruits except for 3,13-dihydroxy GA 15—were compared in six gibberellin bioassays. 相似文献
14.
The properties of the water-soluble metabolites of [ 3H]gibberellin A 1 ([ 3H]GA 1) from lettuce ( Lactuca sativa L.) hypocotyls were compared with those of authentic samples of gibberellin (GA) glucosyl esters and ethers. Partitioning against l-butanol at high and low pH was not an efficient method of differentiating between ester and ether conjugates of GA 1 or GA 3. Extraction into l-butanol at pH 2.5 was, however, useful as a group purification step. Gel-filtration on acrylamide indicated a mean molecular weight of ca. 600 for the polar material and high-voltage electrophoresis separated two compounds (LH 1 and LH 2) with differing charge properties. Both metabolites incorporated 14C from glucose and 3H from GA 1. Subsequent enzymatic hydrolysis of LH 1 released material with identical properties to [ 14C]glucose together with a second uncharacterised component. Feeding with [ 3H]GA 1 methyl ester greatly reduced the formation of LH 1 but not LH 2. The metabolites were provisionally identified as GA 1-glucosyl ester (LH 1) and GA 1-glucosyl ether (LH 2).Abbreviations GA
gibberellin
- LH1
GA 3-glucosyl ester
- LH2
GA 1-glucosyl ether
- HVE
high voltage paper electrophoresis
- TLC
thin-layer chromatography 相似文献
15.
Adenosine is known to exert most of its physiological functions by acting as local modulator at four receptor subtypes named
A 1, A 2A, A 2B and A 3 (ARs). Principally as a result of the difficulty in identifying potent and selective agonists, the A 2B AR is the least extensively characterised of the adenosine receptors family. Despite these limitations, growing understanding
of the physiological meaning of this target indicates promising therapeutic perspectives for specific ligands. As A 2B AR signalling seems to be associated with pre/postconditioning cardioprotective and anti-inflammatory mechanisms, selective
agonists may represent a new therapeutic group for patients suffering from coronary artery disease. Herein we present an overview
of the recent advancements in identifying potent and selective A 2B AR agonists reported in scientific and patent literature. These compounds can be classified into adenosine-like and nonadenosine
ligands. Nucleoside-based agonists are the result of modifying adenosine by substitution at the N
6-, C 2-positions of the purine heterocycle and/or at the 5′-position of the ribose moiety or combinations of these substitutions.
Compounds 1-deoxy-1-{6-[ N′-(furan-2-carbonyl)-hydrazino]-9 H-purin-9-yl}-N-ethyl- β-D-ribofuranuronamide ( 19, hA 1
K
i = 1050 nM, hA 2A
K
i = 1550 nM, hA 2B EC 50 = 82 nM, hA 3
K
i > 5 μM) and its 2-chloro analogue 23 (hA 1
K
i = 3500 nM, hA 2A
K
i = 4950 nM, hA 2B EC 50 = 210 nM, hA 3
K
i > 5 μM) were confirmed to be potent and selective full agonists in a cyclic adenosine monophosphate (cAMP) functional assay
in Chinese hamster ovary (CHO) cells expressing hA 2B AR. Nonribose ligands are represented by conveniently substituted dicarbonitrilepyridines, among which 2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]pyridin-2-ylsulfanyl]acetamide
( BAY-60–6583, hA 1, hA 2A, hA 3 EC 50 > 10 μM; hA 2B EC 50 = 3 nM) is currently under preclinical-phase investigation for treating coronary artery disorders and atherosclerosis.
This article has previously been published in issue 4/4, under doi:. 相似文献
16.
Abstract Synthesis of 2′-deoxy-2′-fluoro- N 6-substituted adenosines as bioisosteres of Cl-IB-MECA and their binding affinities to A 3 adenosine receptor are described. 相似文献
17.
Several N 6 -substituted 3 ′-ureidoadenosine derivatives were efficiently synthesized starting from D-glucose for the development of H272E mutant A 3 adenosine receptor (AR) agonists. Among compounds tested, 3 ′-ureido- N 6 -(3-iodobenzyl)adenosine ( 2c ) exhibited the highest binding affinity ( K i = 0.22 μ M) at the H272E mutant A 3 AR without binding to the natural A 3 AR. 相似文献
18.
Through the use of a single gene dwarf mutant of Zea mays L., dwarf-1, the interaction of growth retardants with gibberellin biosynthesis was studied in Fusarium monitiforme. It was demonstrated that the growth retardants 2-isopropyl-4-dimcthylamine-5-methyphenyl-1-piperidine-cai'boxylate methyl chloride (Amo 1618) and (2-chloroethyl) trimethylammonium chloride (CCC) are more effective inhibitors of gibberellin biosynthesis in cultures maintained under continuous illumination. Light grown cultures produced significantly more biologically active gibberellin-like materials than dark grown cultures. Stock cultures exposed to light also promoted the subsequent biosynthesis of gibberellins in the dark. Chromatographical analysis of the soluble gibberellins extracted from the culture medium revealed that large amounts of chromatographically detectable A 3 and A 7 were produced in light cultures with only A 7 produced in the dark. Light also induced a greater incorporation of acelate-2- 14C into the gibberellins A 7, A 3 and an unidentified gibberellin. Growth returdants occasionally caused a complete disappearance of chromatographically detectable gibberellins in the dark; however, in the light at no concentration tested was it possible to detect the complete disappearance of gibberellin-like material. A 3 was always detectable. Like higher plants, different strains of F. moniliforme exhibit variation which makes them more or less sensitive to the growth retardants. This variation is interpreted to mean that there may be more than one pathway leading to the synthesis of the gibberellins. 相似文献
19.
13C NMR spectroscopy was applied to studying lysine biosynthesis in Corynebacterium glutamicum ATCC 21543, a lysine producing mutant. It was cultured in a medium containing [1- 13C]glucose or [6– 13C]glucose as the sole carbon source and the 13C NMR spectrum of the culture filtrate was measured. C labeling patterns of l-lysine produced were well explained by the putative metabolic pathways of the bacterium. Fixation of 13CO 2 liberated from the labeled substrates and the operation of the tricarboxylate cycle in the fermentation were obviously observed. The dual operations of the classical diaminopimelate pathway and the diaminopimelate dehydrogenase bypath were supported. Calculation of the contribution ratios of the metabolic pathways was attempted. 相似文献
20.
Abstract MC exhibits A 1 and A 2 receptors with opposite actions on cAMP formation and 45Ca 2+ uptake. ADO 10 ?4 M activated both second messengers, but neither A 1 nor A 2 receptors seem to be involved in these ADO-induced effects. 相似文献
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