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1.
(E,E)?[1?14C]Farnesyl phosphate and (E,E)?[1?14C]farnesyl pyrophosphate were both converted to abscisic acid by Cercospora rosicola resuspensions. (E,E)?[1?14C]Farnesol, (E,Z)?[1?14C]farnesol, (E,Z)?[1?14C]farnesyl pyrophosphate, (E,E)?[1?14C]farnesic acid, and (E,Z)?[1?14C]farnesic acid were not converted to abscisic acid by the fungus. These findings provide information on the sequence of the reactions involved in converting farnesyl pyrophosphate to abscisic acid. Specifically, they suggest that the transformations involving the three terminal carbons in the side chain occur after one or more changes elsewhere in the molecule. 相似文献
2.
1′-Deoxyabscisic acid (1′-deoxy-ABA) has been isolated from cultures of Cercospora rosicola which are actively synthesizing abscisic acid (ABA) 相似文献
3.
The biosynthesis of PR toxin was studied by incorporation of [1,2-13C]acetate. The biosynthesis of the eremophilane skeleton of PR toxin follows th 相似文献
4.
Earlier observations of Dawson on the relative incorporation of [2-3H]- and [6-3H]-nicotinic acid into nicotine have been confirmed in intact Nicotiana tabacum plants. All the tritium in the nicotine derived from [2-3H]-nicotinic acid was located at C-2 of the pyridine ring. However the radioactive nicotine derived from [6-3H]-nicotinic acid was not labelled specifically at C-6 with tritium. By carrying out feeding experiments with [6-14-C, 2-3H]- and [6-14C, 3H]-nicotinic acids, it was established that there was very little loss of tritium from C-2 and C-6 of nicotinic acid during 5 days of metabolism in the tobacco plant. 相似文献
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6.
dl-Ornithine-[2,3-13C2] was synthesized from acetate-[1-13C] and ethyl acetamidocyanoacetate-[2-13C]. This labelled material was mixed with dl-ornithine-[5-14C] and fed to Nicotiana glutinosa plants by the wick method. After 10 days the plants were harvested affording radioactive nicotine and nornicotine (0.14% and 0.051% specific incorporations, respectively). Even at these low specific incorporations an examination of their 13C NMR spectra established the incorporation of ornithine symmetrically into the pyrrolidine rings of these alkaloids. Satellites were observable at the signals due to C-2′, 3′, 4′ and 5′ positions, arising by the presence of contiguous carbons at C-2′, 3′ and C-4′, 5′. 相似文献
7.
Nimbolide was biosynthesized from [2-14C, (4R)4-3H1]mevalonic acid lactone in the leaves of Azadirachta indica. The nimbolide had a 3H:14C ratio of 3:5 which gives support to the suggestion of the involvement of a triterpenoid intermediate with a double bond at the Δ8(9)-position in the biosynthesis of nimbolide. 相似文献
8.
(±)-(2Z,4E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid was metabolized by Cercospora cruenta, which has the ability to produce (+)-abscisic acid (ABA), to give (±)-(2Z,4E)-xanthoxin acid, (±)-(2Z,4E)-5′-hydroxy-1′,2′-epoxy-1′,2′-dihydro-β-ionylideneacetic acid, (±)-1′,2′-epoxy-1′,2′-dihydro-β-ionone and trace amounts of ABA. 相似文献
9.
Ergosterol, episterol, 4α-methyl-5α-ergosta-8,24(28)-dien-3β-ol and 24-methylene-24,25-dihydrolanosterol, isolated from Phycomyces blakesleeanus grown in the presence of methionine-[methyl-2H3], each contained two deuterium atoms; lanosterol, however, was unlabelled. The 14C:3H atomic ratio of the following sterols isolated from P. blakesleeanus grown in the presence of mevalonic acid-[2-14C,(4R)-4-3H1], was: ergosterol, 5:3; episterol, 5:4; ergosta-5,7,24(28)-trien-3β-ol, 5:3; 4α-methyl-5α-ergosta-8,24(28)-dien-3β-ol, 5:4; 24-methylene-24,25-dihydrolanosterol, 6:5; lanosterol, 6:5. The significance of these results in terms of ergosterol biosynthesis is discussed. 相似文献
10.
Barry V. Milborrow 《Phytochemistry》1974,13(1):131-136
Abscisic acid (ABA) is synthesized from labelled mevalonate by a preparation of lysed chloroplasts isolated from ripening avocado fruit; a number of cofactors are required. A similar preparation from bean and avocado leaves was also active and chloroplasts from the green, outer, and white, inner parts of the fruit were equally effective. 相似文献
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12.
Edward Leete 《Phytochemistry》1985,24(5):953-955
Radioactive hygrine (2.2% incorporation) was isolated from Nicandra physaloides plants which had been fed Dl-[5-14C]ornithine. A systematic degradation of the hygrine yielded products whose activity was consistent with the pyrrolidine ring of this alkaloid being labeled equally at the C-2 and C-5 positions. The result does not agree with the previous work of O′Donovan and Keogh, whose publication is critically examined. 相似文献
13.
Edward Leete 《Phytochemistry》1975,14(9):1983-1984
The administration of dl-methionine-[114C] to Nicotia tabacum resulted in the formation of radioactive azetidine-2-carboxylic acid (isolated by dilution) which was specifically labelled on its carboxyl group. This result and other evidence strongly indicates that this imino acid is a normal component of tobacco. 相似文献
14.
Akinbo A. Adesomoju Joseph I. Okogun Donald E.U. Ekong Paul Gaskin 《Phytochemistry》1980,19(2):223-225
Abscisic acid, phaseic acid and 4′-dihydrophaseic acid were identified by GC-MS of derivatized (Me, MeTMSi) extracts from immature fruits of Vigna unguiculata. The fruits also contained some other ABA-related compounds, one of which might be epi-4′-dihydrophaseic acid while another was tentatively identified as 6′-hydroxymethylabscisic acid. 相似文献
15.
Michael P. Farinelli K.E. Richardson 《Biochimica et Biophysica Acta (BBA)/General Subjects》1983,757(1):8-14
Hepatectomy significantly altered the metabolism of [1-14C]glyoxylate and [1-14C]glycollate in the rat. The production of 14CO2 was reduced by 47% and 77%–86%, respectively, indicating the involvement of the liver in the oxidation of both substrates. Unidentified intermediates, assumed to be primary glycine, serine and ethanolamine, were also reduced by over 50%, was would be expected from the removal of the aminotransferase enzymes through the hepatectomy. The biosynthesis of [14C]oxalate from [1-14C]glycollate was reduced by more than 80% in the hepatectomized rat. This suggests that this oxidation is primarily catalyzed by the liver enzymes, glycolic acid oxidase and glycolic acid dehydrogenase, in the intact rat. The limited formation of [14C]oxalate from [141]glycollate observed in the hepatectomized rat is probably catalyzed by lactate dehydrogenase or extrahepatic glycolic acid oxidase. Hepatectomy did not significantly alter the rate of formation of [14C]oxalate from [141]glyoxylate. However, since saturating concentrations of glyoxylate could not be used because of the toxicity of this substrate, the involvement of glycollic acid oxidase in this oxidation reaction in the intact rat can not be ruled out. In the hepatectomized rat, lactate dehydrogenase appears to be the enzyme making the major contribution, although other as yet not identified enzymes may be contributing. The increased deposition of oxalate in the tissues, oxalosis, may result from the shift in oxalate synthesis from the liver to the extrahepatic tissues. 相似文献
16.
Labelling experiments with [2-13C]- and [1,2-13C]acetate showed that both photopigments of Anacystis nidulans, chlorophyll a and phycocyanobilin, share a common biosynthetic pathway from glutamate. The fate of deuterium during these biosynthetic events was studied using [2-13C, 2-2H3]acetate as a precursor and determining the labelling pattern by 13C NMR spectroscopy with simultaneous [1H, 2H]-broadband decoupling. The loss of 2H (ca 20%) from the precursor occurred at an early stage during the tricarboxylic acid cycle. After formation of glutamate there was no further loss of 2H in the assembly of the cyclic tetrapyrrole intermediates or during decarboxylation and modification of the side-chains. Thus the labelling data support a divergence in the pathway to cyclic and linear tetrapyrroles after protoporphyrin IX. 相似文献
17.
Protein extract from crown gall tumour tissue, induced on Nicotiana tabacum by Agrobacterium tumefaciens strain T37, synthesized nopalinic acid [N2-(1,3-dicarboxypropyl)ornithine] from l-ornithine and α-ketoglutarate in the presence of NADPH. Label was incorporated into nopalinic acid from both l-ornithine-[14C] and α-ketoglutarate-[14C] in vivo. Nopaline [N2-(1,3-dicarboxypropyl)arginine] did not appear to be metabolized to nopalinic acid in vivo. 相似文献
18.
Abscisic acid and its novel metabolise, which was a conjugated form of hydroxyabscisic acid (Metabolite C), were isolated from seeds of Robinia pseudacacia L. The structure of the conjugate was shown to be (+)-3-methyl-5 - [1(S),6(R) - 2,6 - dimethyl - 1 - hydroxy - 6 - (3 - hydroxy - 3 - methyl - 4 - carboxybutanoyloxymethyl) - 4 - oxo-cyclohex-2-enyl]-2-Z-4-E-pentadienoic acid and tentatively named β-hydroxy-β-methylglutarylhydroxyabscisic acid. 相似文献
19.
Rick C. Heupel Bernard O. Phinney Clive R. Spray Paul Gaskin Jake MacMillan Peter Hedden Jan E. Graebe 《Phytochemistry》1985,24(1):47-53
The native hormones from tassels of maize (Zea mays) were re-investigated. The previous identification by GC/SIM of GA1, GA8 and GA29 in normal tassels was confirmed by full GC/MS scans at the correct Kovats retention indices. In tassels of dwarf-1 mutants, GA44,?GA19, GA17, GA20 and the 16,17-dihydro, 7β,16α,17-trihydroxy derivative of ent-kaurenoic acid were identified by GC/MS. Gibberellin A1 was not found in the mutant tassels. [14C]Gibberellin A53 was fed to tassels of the dwarf-5 mutant. In the ethyl acetate-soluble acidic fraction from the feeds, [14C]GA44 was identified by GC/MS; [14C]GA19 and [14C]GA29 were identified by GC/SIM. The GA29 is probably a metabolite of the feeds because the dwarf-5 mutant is known to control the step copalyl pyrophosphate to ent-kaurene in the maize GA-biosynthetic pathway and because GA29 was not identified in a control experiment. The n-butanol fractions obtained from the feeds were shown, by GC/MS, to contain [14C]GA53 after hydrolysis, suggesting that conjugated [14C]GA53 is a major metabolite from GA53 feeds. [17-13C, 17-3H2]Gibberellin A20 was fed to normal, dwarf-1 and dwarf-5 tassels. In each case, analysis of the purified ethyl acetate-soluble acidic extracts by GC/MS led to the identification of [13C]GA29 and unmetabolized [13C]GA20 in which no 13C-isotope dilution was observed. 相似文献
20.
[14C]Calotropin (11.2 μCi/mmol) and uscharidin (14.1 μCi/mmol) were biosynthesized by stem discs of Asclepias curassavica incubated in a medium containing [1-14C]acetic acid. Relative isotope enrichment sites determined by 13C NMR spectroscopy of [13C]calotropin prepared by the same method were at C-23 (0.71 %), C-2′ (0.28 %) and C-4′ (0.21 %). 相似文献