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1.
Etiolated seedlings of Phaseolus mungo were fed with 14C-glucoseand the incorporation of 14C into shikimic and quinic acidswas determined. The incorporation of 14C into shikimic acidwas enhanced when non-labeled shikimic, quinic or 5-dehydroquinicacid was not significantly affected by these alicyclic acids.To examine whether the difference in biosynthetic patterns betweenshikimic and quinic acids is common in higher plants, flowersand leaves of several plants were fed with 14C-glucose or 14C-erythroseand the effciencies of these labeled sugars as precursors ofshikimic and quinic acids were compared. In seven of eight plantsamples, erythrose was superior to glucose as the precursorof shikimic acid, while there was no great difference in theefficiency of either sugar as the precursor of quinic acid.The possibility that the biosynthetic mechanism for quinic aciddiffers from that for shikimic acid is discussed. (Received September 12, 1973; )  相似文献   

2.
Mesophyll cells isolated enzymatically from Vigna angularisleaves were fed 14Cglucose or 14C-erythrose and the time-courseof 14C incorporation into shikimic and quinic acids was examined.When 14C-glucose was fed to the cells, the highest radioactivityin quinic acid was observed after 10 hr of incubation, whilethat in shikimic acid was after 14 hr. In the experiment with14C-erythrose, the radioactivity in shikimic acid rose strikinglyup to the 3rd hour, but 14C in quinic acid increased graduallyduring the incubation. The incorporation of 14C into shikimicacid was enhanced when unlabeled shikimic or quinic acid wassupplied to the cells simultaneously with either 14C-glucoseor 14G-erythrose, whereas that into quinic acid was not significantlyincreased by these alicyclic acids. The difference in incorporationrate of 14C into quinic acid from that into shikimic acid wasmore conspicuous in the isolated mesophyll cells than in theepicotyls of V. angularis seedlings. 1 Present address: Department of Biology, Faculty of Science,Kumamoto University, Kumamoto 860, Japan. (Received September 22, 1978; )  相似文献   

3.
Shikimate kinase from Phaseolus mungo seedlings was partiallypurified by DEAEcellulose, hydroxyapatite and Sephacryl S-200column chromatographies. The activity was completely inhibitedby EDTA and the requirement for Mg2+ could be partially replacedby Mn2+, Ca2+; Co2+ and Cd2+. Sulfhydryl inhibitor did not inhibitthe enzyme activity. The apparent Km values for shikimic acidand ATP at pH 8.6 were 0.25 mM and 0.38 mM, respectively. Theactivity appeared to be maximal at pH 8.6–9.0. Shikimate-3-phosphateand ADP inhibited the activity slightly. Aromatic amino acids,quinic acid and dehydroquinic acid had no significant effecton the activity. (Received January 11, 1979; )  相似文献   

4.
The time course of 14C incorporation into shikimic (SA) andquinic acids (QA) was examined in Quercus pedunculata seedlingsof different age fed with 14C glucose-6-phosphate (G6P) or 14Cdehydroquinic acid (DHQ). QA was actively synthesized from G6Pand exhibited the highest radioactivity among the organic acids.In contrast, DHQ, a good precursor of shikimate, was poor forquinate synthesis. In both cases, QA and SA presented parallelchanges in specific radioactivities with time. The experimental results suggest that in oak leaves QA is formedby a route that is independent of the shikimate pathway andthat this compound undergoes an important turnover. Moreover,depending on the physiological state of the plants, there aredifferences in the relative biosynthetic rates of the two acids. (Received April 23, 1980; )  相似文献   

5.
Organic acid metabolism and ethylene formation during controlledatmosphere storage (CA-storage) of apples (Mallus pumila MILLER,cv Rolls) were studied. A higher titratable acidity was observedin apples during CA-storage as compared to those in air control.The incorporation of atmospheric 14CO2 into malic acid was greaterin apples stored in the higher CO2 concentration. The conversionof succinic acid-14C into fumaric acid-14C was slightly lessin the apple in modified high carbon dioxide atmosphere thanthose in air. O2 uptake and CO2 output by apple slices weremarkedly inhibited by the addition of succinic and malic acidsat a concentration higher than 25 mM. These factors seem to be the possible cause of a higher acidityof fruits stored in CA-condition. Ethylene production from wholefruits or tissue slices was markedly inhibited under CA-condition. The retardation of acid metabolism and the inhibition of ethyleneproduction of apples during CA-storage seem to be the importantfactors which help to maintain their storage quality. (Received March 18, 1970; )  相似文献   

6.
When either trans-cinnamic acid-2-14C or quinic acid-G-3H wasadministered to sweet potato root discs, each compound was incorporatedinto chlorogenic acid. Hydrolysis analysis revealed that trans-cinnamicacid-2-14C and quinic acid-G-3H were selectively incorporatedinto the aromatic and non-aromatic moieties of chlorogenic acid,respectively. Quinic acid-G-3H was considered a more efficient precursor thantrans-cinnamic acid-2-14C, based on data of dilution values,incorporation percents and pool sizes in the tissue. No conjugatesof trans-cinnamic acid and quinic acid were detected in discsadministered trans-cinnamic acid-2-14C or quinic acid-G-3H.From these experimental results, a possible biosynthetic pathwayfor chlorogenic acid has been proposed. 1 This paper constitutes Part 98 of the Phytopathological Chemistryof Sweet Potato with Black Rot or Injury. (Received November 2, 1971; )  相似文献   

7.
Young mung bean plants (Phaseolus mungo) were exposed to 14C-shikimateor 14C-quinate in the light. After 8 or 23.5 hr of incubationat 25°C, radioactivities in free and bound amino acids,organic acids, soluble and insoluble carbohydrates, ether-solublefraction and lignin were determined. Shikimic and quinic acidswere separated by the combined use of paper-chromatography andcolumn chromatography. Specific activity of formed quinate orshikimate was only slightly lower than that of fed shikimateor quinate. Specific activities of phenylalanine, tyrosine andbound tryptophan were high as compared with those of non-aromaticamino acids. Discussion is focused upon the interconversionbetween shikimate and quinate, and their roles in the biosynthesisof aromatic amino acids. (Received November 15, 1968; )  相似文献   

8.
When tea plants were shaded with black lawn cloth for severaldays in the field, the accumulations of (—)-epicatechin,(—)-epicatechin-3-gallate, (—)-epigallocatechinand (—)-epigallocatechin-3-gallate decreased in newlydeveloping tea shoots. Radioactive tracer studies showed thatthe conversions of glucose-U-14C, shikimic acid-G-14C and phenylalanine-U-14Cinto (—)-epicatechin and (—)-epigallocatechin moietieswere depressed by the shade treatment for tea plants but theincorporation of trans-cinnamic acid-3-14C was not affected.The treatment was found to have no significant effect on theactivities of phospho-2-keto-3-deoxy-heptonate. aldolase (EC.4.1.2.15 [EC] ), 3-dehydroquinate synthase (EC. 4.6.1.3 [EC] ), 3-dehydroquinatedehydratase (EC. 4.2.1.10 [EC] ), shikimate dehydrogenase (EC. 1.1.1.25 [EC] )and trans-cinnamate 4-monooxygenase (EC. 1.14.13.11 [EC] ) in theshoots, whereas the activity of phenylalanine ammonia-lyase(EC. 4.3.1.5 [EC] ) clearly decreased. (Received March 17, 1980; )  相似文献   

9.
The formation of shikimic acid and lignin from glucose in thecambium tissue was investigated. Glucose-1-14C, shikimic acid-G-14C, sodium acetate-1-14C and sodium acetate-2-14C were administeredto the tissue culture of strob pine. Glucose was well incorporatedinto shikimic acid, but acetic acid was less effective. Shikimicacid was very efficient as a precursor of aromatic nucleus andglucose was also converted efficiently to lignin. The extentof incorporation of acetic acid, however, was considerably low.A possibility was discussed that in the cultured tissue ligninand its precursor were synthesized from glucose via the shikimicacid pathway. (Received May 14, 1960; )  相似文献   

10.
The metabolism of ribosylzeatin (RZ) was studied using tobaccocrown gall cells which produce RZ as one of the major endogenouscytokinins. When [8-14C]RZ was fed to the cells, it was convertedinto its phosphate (which was rigorously determined to be the5'-monophosphate), RZ-O-glucoside, inosine (or its phosphate),adenosine and adenosine-O-glucoside. When [8-14C]N6-(2-isopentenyl)adenosine(i6Ado), a probable precursor of RZ, was fed to the cells, itwas converted into (i6Ado)-O-glucoside, inosine (or its phosphate),adenosine, adenosine-O-glucoside and adenosine phosphate, butno incorporation of radioactivity into RZ was observed. Thepresent study led to the following conclusions: i) i6Ado isnot a precursor of RZ in the cells, ii) both deaminase and cytokininoxidase are involved in the catabolism of cytokinin, and iii)the metabolism of RZ is quite different from that of i6Ado. (Received December 24, 1985; Accepted April 1, 1986)  相似文献   

11.
The R- and S-enantiomers of racemic [2-14C]Me 1', 4'-cis-diolof abscisic acid have been separated by high performance liquidchromatography on an optically-active Pirkle column. R-[2-14C]-and S-[2-14C]abscisic acids, formed from the Me 1', 4'-cis-diolby oxidation and alkyline hydrolysis were fed to tomato shootsand the extracts analysed by reversed phase high performanceliquid chromatography. R-[2-14C]abscisic acid formed mainlythe abscisic acid glucose ester (ABAGE), abscisic acid l'-glucoside(ABAGS) and an uncharacterized conjugate. Dihydrophaseic acid4'-B-D-glucoside, the major metabolite of RS-abscisic acid intomato shoots, was found to be derived virtually exclusivelyfrom the natural, S-abscisic acid. Phaseic acid and conjugatesof abscisic acid were also found as products of the naturallyoccurring enantiomer. The resolution method was used to measurethe relative proportions of R and S enantiomers in the freeacid liberated from conjugates formed from RS-[2-14C]ABA fedto shoots. The ratios show an excess of the R-enantiomer: 5.8:1, ABAGE; 29.4: 1, ABAGE; 8.3: 1 for an uncharacterized conjugateand 6.1: 1 for the residual free [2-14C]ABA. Key words: ABA, HPLC, Tomato  相似文献   

12.
Glycollic acid-1-14C, glyoxylic acid-2-14C, glycine-1-14C, andglycine-2-14C were fed to illuminated excised leaves of Pisumsativum and the distribution of 14C determined in the glycine,serine, sucrose, and insoluble polyglucan formed. Carboxyl-labelledglycollic acid and glycine gave rise to randomly labelled polyglucanand sucrose although the serine formed was predominantly carboxyllabelled. By contrast glyoxylic acid and glycine labelled inthe -carbon did not give rise to randomly labelled serine, sucrose,or polyglucan.  相似文献   

13.
The Metabolism of Abscisic Acid   总被引:7,自引:2,他引:5  
The light-catalysed isomerization of (+)-abscisic acid (ABA)to its trans isomer during isolation from leaves was monitoredby the addition of (±)-[2-14C]ABA to the extraction medium.(+)Trans-abscisic acid (t-ABA) was found to occur naturallyin rose (Rosa arvensis) leaves at 20µg/kg fresh weight;(+)-ABA was present at 594µg/kg. (±)-[2-14D]Trans-abscisicacid was not isomerized enzymically to ABA in tomato shoots. (±)-Abscisic acid was converted by tomato shoots to awater-soluble neutral product, ‘Metabolite B’, whichwas identified as abscisyl-ß-D-glucopyranoside. When(±)-[2-14C]trans-abscisic acid in an equimolar mixturewith (±)-[2-14C}ABA was fed to tomato shoots it was convertedto its glucose ester 10 times faster than was ABA. Trans-abscisyl-ß-D-glucopyrano8ide only was formedfrom (±)-[2-14C]t-ABA in experiments lasting up to 30h. Glucosyl abscisate was formed slowly from ABA and the freeacid fraction contained an excess of the unnatural (–).ABAas did the ABA released from abscisyl-ß-D-glucopyranosideby alkaline hydrolysis. The (+).ABA appeared to be the solesource of the acidic ‘Metabolite C" previously noted. The concentrations of endogenous (+)-, (+)-[2-14C]-, and (–)-[2-14C]ABAremaining as free acid, and also in the hydrolysate of abscisyl-ß-D-glucopyranoside,were measured by the ORD, UV absorption, and scintillation spectrometryof highly purified extracts of ABA from tomato shoots whichhad been supplied with racemic [2-l4C]ABA.  相似文献   

14.
The effect of low temperatures on the fatty acid compositionof phosphatidylglycerol (PG) in thylakoid membranes, in particularon the ratios of nmol% 16:1(3t) (mg fresh weight)–1 ofcotyledons and nmol 16:1(3t) (mg chlo rophyll)–1 weremeasured during squash seedling growth. Plants were germinatedand grown for one day at 30°C then were either kept at 30°C(control plants) or trans ferred to low temperatures (18, 14or 10°C). When plant were transferred from 30°C to lowtemperatures, the increase in fresh weight was gradually limited.The lowe the temperature, the smaller was the fresh weight.In contrast, the relative content of 16:1(3t) and 18:3, as wella the ratios of nmol 16:1(3t) (mg chlorophyll)–1 and mol%16:1(3t) (mg cotyledon fresh weight)–1 increased indicatingthat the increase of fresh weight and chlorophyll was mor sensitiveto low temperature than PG desaturation in thyla-koid membranes.Furthermore, low temperatures inducei an increase in 16:1(3t)and 18:3 (the final products of PC synthesis) at the expenseof 16:0 and 18:1 (the initial products of PG synthesis). However,within a range of temperature from 10 to 18°C, the extentof these changes (nmol% of 18:3 or 16:1(3t) per day) was graduallylimited by lower temperatures. We therefore propose that lowtemperature inhibit both fatty acid synthesis and desaturationactivities. However, at low temperatures the fatty acid synthesisis likely to be more strongly inhibited than the desaturationactivities, thus explaining the observed increase in the relativecontent of PG-18:3 and PG-16:l(3t). Results an discussed interms of the mechanism which could be in volved in the metabolismof PG in squash cotyledons. (Received July 5, 1996; Accepted March 10, 1997)  相似文献   

15.
Both cytokinins and fusicoccin (FC) stimulated the transpirationand the amino acid accumulation in leaf discs of Brassica campestrisvar. komatsuna. Enhancement effects were of the same magnitude.Both the accumulation and the transpiration were similarly inhibitedwhen vaseline was smeared on the leaf surface. Abscisic acid(ABA) also inhibited those cytokinin-induced effects. The accumulationof amino acid-14C was at the cytokinin- or FC-treated site unlessthe leaf surface was smeared with vaseline. These facts suggestthat cytokinin- or FC-induced amino acid accumulation in leafis caused by the stimulation of transpiration. Present address: 1 Department of Environmental Studies, Collegeof Integrated Arts & Sciences, Hiroshima University, Higashisenda-machi,Hiroshima 730, Japan. Present address: 2 Mitsui Memorial Hospital, 1-Kanda-Izumicho,Chiyoda-ku, Tokyo 101, Japan. (Received May 26, 1977; )  相似文献   

16.
Much of the work on the distribution of 14C-labelled assimilatesin tomato has been done in winter under low light intensities,and consequently the reported distribution patterns of 14C maynot be representative of plants growing in high light. Further,there are several somewhat conflicting reports on patterns ofdistribution of 14C-assimilates in young tomato plants. We soughtto clarify the situation by studying the distribution of 14C-assimilatesin tomato plants of various ages grown in summer when the lightintensity was high. In addition, the role of the stem as a storageorgan for carbon was assessed by (a) identifying the chemicalfractions in the stem internode below a fed leaf and monitoring14 C activity in these fractions over a period of 49 d, and(b) measuring concentrations of unlabelled carbohydrates inthe stem over the life of the plant. The patterns of distribution of 14C-assimilates we found fortomato grown under high light intensity confirmed some of thosedescribed for plants grown under low light, but export of 14Cby fed leaves was generally higher than reported for much ofthe earlier work. Lower leaves of young plants exported over50% of the 14C they fixed, although export fell sharply as theplants aged. Initially, the roots and apical tuft were strongsinks for assimilates, but they had declined in importance bythe time plants reached the nine-leaf stage. On the other hand,the stem became progressively more important as a sink for 14C-assimilates.Older, lower leaves exported more of their 14C-assimilates tothe upper part of the plant than to the roots, whereas youngleaves near the top of the plant exported more of their assimilatesto the roots. The stem internode immediately below a fed leafhad about twice the 14C activity of the internode above theleaf. Mature leaves above and below a fed leaf rarely importedmuch 14C, even when in the correct phyllotactic relationshipto the fed leaf. In the first 3 d after feeding leaf 5 of nine-leaf plants, theorganic and amino acid pools and the neutral fraction of theinternode below the fed leaf had most of the 14C activity, butby 49 d after feeding, the ethanolic-insoluble, starch and lipidfractions had most of the 14C activity. Glucose, fructose andsucrose were the main sugars in the stem. Although concentrationsof these sugars and starch declined in the stem as the plantsmatured, there was little evidence to indicate their use infruit production. Stems of plants defoliated at the 44-leafstage had lower concentrations of sugars and starch at maturity,and produced less fruit than the controls. It was concludedthat tomato is sink rather than source limited with respectto carbon assimilates, and that the storage of carbon in thestem for a long period is possibly a residual perennial traitin tomato.Copyright 1994, 1999 Academic Press Lycopersicon esculentum, tomato, assimilate distribution, 14C, internode storage, sink-source relationships, starch, stem reserves, sugars  相似文献   

17.
Mycclia of Neurospora crassa wild type (FE SC no. 853), harvestedduring the exponential phase of growth on defined minimal mediaincorporated glycine-2-14C, serine-3-14C and formate-14C intoproteins, DNA and RNA. Supplementing the growth medium with1 mM glycine increased the flow of glycine and formate carboninto these products. In contrast, this supplement decreasedthe incorporation of serine-14C. When such cultures were preincubatedfor 30 min with adenine, formaldehyde, formate or L-methionine,labelling of the nucleic acids and protein fractions by glycine-2-14Cwas altered. It is concluded that glycine increases the turnoverof C1 units in Neurospora, resulting in greater contributionsof the C-2 in nucleic acid and protein synthesis. (Received May 14, 1977; )  相似文献   

18.
5-Keto-D-[1-14C]gluconic acid, the most effective precursorof L(+)tartaric acid among all labeled compounds which haveever been tested in grapes, was found to be a good precursorof L(+)tartaric acid in a species of Pelargonium. The synthesisof labeled L(+)tartaric acid from D-[1-14C]glucose in Pelargoniumwas remarkably depressed when a 0.5% solution of D-gluconateor 5-keto-D-gluconate was administered continuously to leavestogether with D-[1-14C]glucose. Our results provide strong evidence that D-[1-14C]glucose ismetabolized in Pelargonium to give labeled L(+)tartaric acidvia (probably D-gluconic acid and) 5-keto-D-gluconic acid withoutpassing through L-ascorbic acid. Labeled L-idonic acid was found in young leaves of Pelargoniumwhich had been labeled with L-[U-14C]ascorbic acid. The synthesisof the labeled L-idonic acid increased when a 0.1% solutionof L-threonate was administered continuously to leaves togetherwith L-[U-14C]ascorbic acid. Specifically labeled compounds, recognized as the members ofthe synthetic pathway for L(+)tartaric acid from L-ascorbicacid via L-idonic acid in grapes, were administered to youngleaves of Pelargonium. Each compound (2-keto-L-[U-14C]idonicacid, L-[U-14C]idonic acid, 5-keto-D-[1-14C]gluconic acid and5-keto-D-[6-14C]gluconic acid) was partly metabolized, as ingrapes. The metabolic pathway starting from L-ascorbic acidto L(+)tartaric acid via L-idonic acid, however, did not actuallycontribute to the synthesis of L(+)tartaric acid in Pelargoniumprobably because the activity of each metabolic step was muchlower than that observed in grapes. (Received May 28, 1984; Accepted July 30, 1984)  相似文献   

19.
When indole-3-acetic acid (IAA) is applied to the cotyledonsof broad bean seedlings (Vicia faba L. cv Chukyo), the majormetabolites found in the roots are 3-(O-ß-glucosyl)-2-indoIone-3-acetylaspartic acid (Glc-DIA-Asp) and 3-hydroxy-2-indolone-3-acetylasparticacid (DIA-Asp). In this report, the metabolic pathway from IAAto the two dioxindole-3-acetic acid (DIA) conjugates was investigatedby using [14C]IAA, [14C]DIA, [14C]indole-3-acetylaspartic acid(IAA-Asp), and [14C]IAA-[3H]Asp. The precursor of DIA-Asp wasfound to be IAA-Asp but not DIA. Incorporation of the doublelabeled IAA-Asp into the DIA conjugates demonstrated that hydrolysisof IAA-Asp was not involved in the formation of the DIA conjugates.DIA-Asp was further metabolized to Glc-DIA-Asp in the cotyledons,while formation of Glc-DIA-Asp in the roots was very low. Glc-DIA-Aspformed in the cotyledons was transported to the roots. (Received April 21, 1986; Accepted September 10, 1986)  相似文献   

20.
Changes in respiration rate and in the contents of various constituentsduring the early period of germination of Phaseolus mungo seedswere studied. The course of the respiration developed in threephases. A sharp rise was observed in the first phase (Phasea), followed by the second phase (Phase b) of fairly constantrespiration rate. The respiration rate increases again in thethird phase (Phase c). The O2 uptake in Phases a and b was notinhibited by iodoacetate and fluoroacetate, while that in Phasec was inhibited. The contents of aspartic and glutamic acidsand amides were very high. A decrease of aspartic acid contentwas notable during the first few hours of germination. Citricand malic acids were the major organic acid constituents. Citricacid content in the seeds decreased, while that of malic acidremained unchanged. The leaching of malic acid into the soakingmedium was remarkable during the first 6 h of imbibition  相似文献   

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