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1.
Subunits (, ß, ) and mixtures of subunits ( ß, , ß , ß ) were isolated without denaturationfrom a chloroform extract of chloroplast coupling factor 1 (CF1)from maize (Zea mays var. Ushiku 5-4) and from spinach by fastprotein liquid chromatography (FPLC), on an anion-exchange columnof Mono-Q in the presence of n-octylglucoside (OG) and on achromatofocusing column of Mono-P. The ß -subunitcomplex (CF1 ß ) was the minimum unit required forATPase activity, as was confirmed by the reconstituted complexof ß and subunits. An subunit isolated from maizeinhibited the ATPase activity of CF1 ß from bothmaize and spinach. CF1 ß was found to contain anOG-dependent Mg2+-ATPase. The ATPase activity of CF1 ß required divalent cations, such as Mg2+ or Mn2+, for its expressionin the presence of OG; its optimum pH was 8.0 and it was markedlyinhibited by NaN3. The enzyme hydrolyzed ATP in prefernece toGTP but not CTP, UTP, ADP, AMP or pNPP. Lineweaver-Burk plotsof its activity were curvilinear in the range of 0.6–0.7mM ATP.Mg2+. 1Present address: Department of Biology, School of Education,Waseda University, Shinjuku-ku, Tokyo, 160 Japan. (Received February 15, 1989; Accepted April 20, 1989)  相似文献   

2.
The effect of growth temperature on the compositions of phospholipidsand fatty acids of the psychrotrophic bacterium Pseudomonassp. strain E-3 was studied. The composition of phospholipids(phosphatidylethanolamine, phosphatidylglycerol and cardiolipin)did not differ significantly in cells grown at 5?, 15?, and30?C. Phosphatidylethanolamine (PE) was the most abundant, amountingto over 70% of total phospholipids. When the growth temperaturewas lowered, palmitoleic [16:1(9)] and cis-vaccenic [18:1(11)]acids increased at the expense of palmitic (16:0) acid, especiallyin PE. In vivo experiments using [l-14C]16:0 showed that incorporationof radioactivity into 16:1(9) was oxygen-dependent and cerulenin-insensitive,and incorporation into 18:1(11) was cerulenin-sensitive. Theseresults suggest that 16:0 was aerobically desaturated to 16:1(9)and subsequently elongated to 18:1(11). Desaturation activityof 16:0 in the cells grown at 25?C was enhanced by loweringthe assay temperature. (Received February 12, 1987; Accepted July 10, 1987)  相似文献   

3.
Nucleoside triphosphate(NTP)-binding proteins were detectedin the crude extract of mycelia of Neurospora crassa, whichwas treated with 1% Lubrol PX and fractionated by gel filtration.Protein fractions showing the capacity to bind [35S]ATPS or[35S]GTPS were designated as AGN1 to 6. The binding of [35S]ATPSor [35S]GTPS was prevented in the presence of 0.1 mM ATP orGTP except that in fractions AGN1 and 2, the presence of GTPstimulated the binding of [35S] ATPS to ATP(NTP)-binding proteins.ATP or GTP was 1 to 2 orders of magnitude more effective thanCTP or UTP in preventing the binding of [35S]GTPS in AGN1, 2and 5. Among these fractions AGN1, 2, 5 and 6 showed activityto hydrolyze 1 nM [–32P]ATP or [–32P]GTP. NTP-bindingproteins bound with [35S]ATPS or [35S]GTPS had lower apparentmolecular weights than the same proteins without bound nucleotide.Proteins bound with [35S]ATPS or [35S]GTPS and those [32P]ADP-ribosylatedby endogenous ADP-ribosyl transferase in each fraction wereanalyzed by SDS-PAGE. About 20 species of ATP or ATP-GTP-bindingproteins were detected, several of which were ADP-ribosylated.The binding of [35S]ATPS or [35S]GTPS to NTP-binding proteinswas confirmed by the comparison of non-boiled and boiled samplesimmediately before loading to SDS-PAGE. ATP, GTP, CTP or UTPat the concentration of 0.1 mM effectively removed [33S]ATPSor [35S]GTPS bound to NTP-binding proteins. (Received December 10, 1990; Accepted April 18, 1991)  相似文献   

4.
The sexual agglutinability of haploid cells of heterothallicSaccharomyces cerevisiae was repressed when they were culturedin the absence of easily fermentable sugars, such as glucoseand mannose. The repression was reversed by the action of hormone-likesubstances of the opposite mating types. The substance producedby mating type cells was identical to subtsance-I which isknown to induce sexual agglutinability of inducible matingtype cells. The mating type cells produce a new hormone-likesubstance which induces or enhances sexual agglutinability of mating type cells. A crude fraction of the mating type-specific substance ( substance-I)was obtained by passing the culture filtrate of mating typecells through Amberlite CG-50 (H+ form), followed by elutionwith 1.5 M ammonia. 2 On leave from Osaka City University. (Received December 25, 1975; )  相似文献   

5.
A Ras-related NTP-binding protein was partially purified froma membrane fraction derived from the mycelia of Neurospora crassa.[-32P]ATP and [-32P]GTP were incubated with mem brane and solublefractions which were then irradiated with UV light to inducecrosslinking of tightly bound nucleotides. After SDS-polyacrylamidegel electrophoresis, blotting onto a nitrocellulose filter andautoradiography it was apparent that most of the proteins thatbound [-32P]-GTP also bound [-32P]ATP. Pretreatment of the membranefraction with Ras-specific antibody effectively blocked thebinding of [-32P]ATP and [-32P]GTP to several ATP-GTP-bindingproteins. The band of a protein with a molecular weight of 26kDa on the SDS-polyacrylamide gel cross-reacted strongly withthe Ras-specific antibody. The protein was extracted from thegel and further purified by repeated gel electrophoresis. Thepurified protein bound [-32P]ATP, [-32P]-GTP, [-32P]CTP and[-32P]UTP at 1.6x10 M and was autophosphorylated in thepresence of [-32P]ATP and [-32P]GTP at 1.7x10 M. Pretreatmentof the protein with Ras-specific antibody partially blockedthe autophosphorylation in the presence of these nucleotides.The binding of [-32P]ATP to the NTP-binding protein was blockedby addition of ATP at 10–4–10–3 M. ATP ata concentration of 10–4 M prevented the binding of [-32P]to a greater extent than did GTP at the same concentration.Binding of [-32P]CTP and [-32P]UTP to the protein was also observed. (Received October 7, 1991; Accepted July 14, 1992)  相似文献   

6.
7.
Enzymatic Degradation of Chlorophyll in Chenopodium album   总被引:3,自引:0,他引:3  
The breakdown of chlorophyll (Chi) in crude extracts of Chenopodiumalbum (white goose foot) in the dark was examined. Derivativesof pheophorbide were formed when Chi or chlorophyllide wasincubated with depigmented crude extracts. The formation ofpheophorbide was completely prevented by heat treatment of extracts,indicating that the reaction was enzymatic, and the presenceof a Mg-releasing enzyme, the so called Mg-dechelatase, waspostulated. This hypothesis was strongly supported by the observationthat the formation of pheophorbide was inhibited by 51% by 10mM MgCl2. Analysis by high-performance thin-layer chromatography(HPTLC) and liquid chromatography (HPLC) showed that the appearanceof chlorophyllide , pheophorbide 132-hydroxychlorophyllide and pyropheophorbide was accompanied by a concomitant decreasein levels of Chi The formation of 132-hydroxychloro-phyllide was not clearly an enzymatic reaction and requires furtherexamination. It appears that Chl is degraded in a crude extractof C. album via the following enzymatically catalyzed reactions (Received September 10, 1990; Accepted November 15, 1990)  相似文献   

8.
Sixteen legumes were grown in N-free media so that N was suppliedentirely by symbiotic N2 fixation. The plant tissues were analyzedfor natural 15N abundance (expressed as 15N per mil relativeto air N2) with a ratio mass spectrometer. The nodules of desmodium,centro, siratro, soybean and winged bean showed high enrichmentin 15N (+9), while red clover showed slight enrichment (+2).The nodules of 9 other forage legumes (Townsville stylo, whiteclover, alsike clover, common vetch, Chinese milk vetch, senna,alfalfa, ladino clover, and hairy vetch) showed little enrichmentin 15N. In all the legumes investigated, particularly in the ureide-transportingplants such as desmodium, centro, siratro, soybean, winged beanand field bean, the 15N value of the shoots was negative (–3.2).The 15N value of the shoots in winged bean and field bean variedby about 1 depending on the Rhizobium strains used. The isotopicmass balance of 13 legumes indicated that isotopic fractionationoccurs during N2 fixation by the legume-rhizobia symbiosis witha preference for 14N over 15N, resulting in a 15N value of –0.2to –2 in the whole plant. The results indicate that 15N/14N isotopic discrimination witha preference for the lighter atom may occur in both N2 fixationand export of fixed N from nodules. 1Present address: Department of Soils and Fertilizers, NationalAgriculture Research Center, Kannondai, Tsukuba, Ibaraki 305,Japan. (Received October 8, 1985; Accepted April 7, 1986)  相似文献   

9.
Effects of l, N6-ethenoadenylates (e-adenylates) were testedon phosphorylation, and electron transport under phosphorylation,arsenylation and quasi-arsenylation (stimulation of electrontransport in the presence of ATP, AMP and arsenate) conditionsin isolated spinach chloroplasts. -ATP as well as ATP partially inhibited ferricyanide reductionthrough binding to the chloroplast coupling factor 1 with anapparent dissociation constant (KDapp) of around 5µM,which was remarkably larger than that for ATP (ca. 2µM).e-ATP at below 500 µM had no effect on phosphorylationbut inhibited quasi-arsenylation in competition with ATP withan apparent inhibition constant (K1app) of around 60 µM. -ADP as well as ADP partially inhibited ferricyanide reductionwith a KDapp value close to that for -ATP. -ADP was phosphorylated(the apparent Michaelis constant, Kmapp=80µM) accompanyingstimulation of ferricyanide reduction to the magnitude predicted(P/e=l). -ADP-arsenylation was also detected by stimulationof ferricyanide reduction. -AMP alone caused little inhibition of ferricyanide reductionas AMP, but competitively depressed the electron transport inhibitionby ADP and ATP with a K1app value of around 200 µM. -AMPwas not effective for ADP phosphorylation but inhibited stimulationdue to quasi-arsenylation coupling in competition with AMP K1app=150µM Among the possible combinations of adenylates and -adenylatesfor quasiarsenylation, only [ATP+AMP] could couple with theenergy transduction mechanism. Based on the specificity of binding sites to adenylates and-adenylates, an attempt was made to distinguish at least four(two pairs) kinds of binding sites (at least six sites in toto)on the chloroplast coupling factor 1 for photosynthetic energytransduction. When one pair of sites is occupied by the designatedadenylates or -adenylates (allosteric effectors), the couplingfactor is thought to be in a conformation for coupling withthe energy transduction mechanism in the presence of phosphateor arsenate. 1Presented to the 1st Symposium of Japan Bioenergetics Group,December 19, 1975, Osaka. (Received February 17, 1976; )  相似文献   

10.
Uptake of the toxic heavy-metal, thallium, was studied in thecyanobacterium Synechococcus R-2 (PCC 7942) using clinicallyavailable 201Tl +. Thallium was found to distribute across theplasmalemma passively, and so the accumulation ratio of theion ([Tl+]i/[Tl+]o) could be used to calculate the apparentmembrane potential (­i,o) of the cells (ETI+i,o = ­i,o).The permeability of the plasmalemma to TI+ (PTI+ 1 to 5 nms–1)is higher than that of K+. Valinomycin does not increase thepermeability of TI+. Transient changes in the ­i,o of cells,because of electrogenic transport of ions, could be detectedfrom its effects upon the uptake rate of TI+. HCO3 hyperpolarizedSynechococcus cells, whereas NH+4, CH3NH+, and K+ led to depolarization.The use of TI+ as a reporter of ­i,o has some inherent limitations.Tl+ is toxic at very low concentrations (inhibitory effectsare apparent after about 6 h at concentrations as low as 1 mmolm–3). The rate of equilibration is slow (t1/25 to 20 min).Equilibration of TI+ takes about 2 h, which limits its valueas a membrane potential probe. Large amounts of TI+ bind tothe surface of the cells making the method impracticable formeasuring accumulation ratios of less than about 10 (­i,o)values smaller than about –60 mV). Cultures continuouslyexposed to Tl+ (10 mmol m–3) eventually become TI+ resistantby actively extruding TI+ (µTI+i,o= –3±0.2kJ mol–1) and so thallium cannot be used as a ­i,oprobe in such cells. (Received October 28, 1997; Accepted August 31, 1998)  相似文献   

11.
An -glucan was isolated from 11-day-old suspension-culturedrice cells by extraction with hot Na-phosphate buffer (pH 6.8).The -glucan had []D=+234? (C = 0.14, in water) and its averagemolecular weight was estimated to be about 1.4 ? 104, basedon elution characteristics on acalibrated Sepharose CL-6B column.Upon partial acid hydrolysis, the -glucan gave mainly malto-oligosaccharides.The maximum absorption of the iodine complex of the -glucanin the presence of Na2SO4 was at 470 nm. The results of hydrolysisby , ß- and iso-amylases and methylation analysisindicated that the isolated -glucan is a highly branched polysaccharidewith an average chain length of 9. The exterior and interiorchain lengths of the -glucan were calculated to be 5 and 3,respectively. (Received July 23, 1986; Accepted February 7, 1987)  相似文献   

12.
Various Cucurbita seed globulins showed patterns similar toone another on SDS-gel electrophoresis, and ß bandsfor unreduced globulins and , ', and ' bands for reduced ones.On gel electrophoresis in 6 M urea, reduced globulin gave twoacidic and two basic bands. These corresponded to and ' chainsand 1 and 2 chains, respectively, identified by two-dimensionalurea-SDS gel electrophoresis. The compositions of the and ßsubunits were proposed. (Received September 8, 1977; )  相似文献   

13.
A b-type cytochrome having an -band at 560 nm was isolated fromspinach leaves (Spinacia oleracea). A method is described forpreparing this cytochrome, cytochrome b-560 (spinach), in apurified state. The cytochrome has, in its reduced state, absorption bands at560 nm (), 530 nm (ß) and 427 nm (); and in the oxidizedstate at 562 nm (), 529 nm (ß) and 417 nm (). Thepyridine ferro-haemochrome prepared from cytochrome b-560 hadan -band at 556.5 nm, indicating the protohaem-nature of theprosthetic group. The cytochrome has an oxidation-reduction potential (E'0) of+0.13V at pH 7.0, as measured using the ferri-ferro oxalate system. The cytochrome is rapidly reduced on illumination with red orfar-red light in the presence of spinach chloroplasts and isoxidized at a slower rate in the dark. This photoreduction isinhibited by 1x10–6 M 3-(3,4-dichlorophenyl)-1,1-dimethylurea(DCMU). The molecular weight of the cytochrome is 30,000 asestimated by the dextran gel filtration method. (Received December 3, 1971; )  相似文献   

14.
Lipid peroxidation induced by Fe2+ADP in soybean mitochondriais stimulated by pyruvate, malate (in the presence of NAD2+)and by NAD(P)H. This lipid peroxidation is almost completelyinhibited by EDTA indicating that iron is essential. Also salicylhydroxamicacid, a specific inhibitor of the alternate oxidase, is a stronginhibitor of lipid peroxidation but its effect should be relatedto chelation or to a general antioxidant action. Rotenone doesnot show any effect on the malateNAD2+Fe2+ADP-induced lipidperoxidation. From the reported data, it is possible to concludethat, in soybean mitochondria, the peroxidation of unsaturatedlipids can be modulated through a balance between the systemssparking lipid peroxidation, like NAD(P)H Fe2+ADP, and the systemswhich protect against it, i.e. quinones, maintained at the reducedstate by the substrates. (Received April 20, 1987; Accepted July 21, 1987)  相似文献   

15.
The natural 13C abundance (13C value) of the field-grown leguminousplants (soybean, kidney bean, pea, azuki bean, mung bean, peanutand cowpea) was investigated by mass spectrometry with a precisionbetter than %0.2 for 13C. Among organs of premature plants,the leaves had the most negative values, and the nodules generallyhad the least negative values, and other organs, fruits, stemsand roots, showed intermediate values. In the soybeans so farinvestigated, the grains of nodulating plants exhibited higher13C values than nonnodulating lines. The 13C values of the grainsvaried depending on the species: peanuts showed the most negativevalues. Possible causes underlying these variations are discussed. (Received March 2, 1983; Accepted May 27, 1983)  相似文献   

16.
Komatsuna (Brassica campestris L. var. rapa) plants were grownhydroponically under various conditions with respect to thesupply of nitrate, and the variations in levels of natural 15Nabundance (15N) in nitrogenous fractions of leaf blades, petiolesplus midribs, and roots in these plants were analyzed. The fractionation of nitrogen isotopes during uptake of nitratewas null irrespective of the concentrations of nitrate in theculture medium. The roots had lower 15N values than that inthe nitrate applied to plants. The nitrate in the three tissuesexamined had higher 15N values than that in the nitrate applied:the values were highest in the leaf blades which were presumedto have highest activities in terms of reduction of nitrate.In contrast, the amino acids and residual fractions had lower15N values than those in the nitrate applied. These resultssuggest that reduction of nitrate is a critical step in thefractionation of nitrogen isotopes in plant tissues in vivo. 1Permanent address: Fukuoka Agricultural Experiment Station,Yoshiki 587, Chikushino, 818 Japan. (Received March 10, 1989; Accepted July 10, 1989)  相似文献   

17.
We found a substance which binds to substance-I to inactivatethe biological activity of the pheromone to induce sexual agglutinabilityof a mating type cells. Both living and boiled cells of thea mating type had the substance-I-absorbing action. The absorbingaction of living cells was detected almost equally at both 0and 28?C. Cell extract of the a mating type showed the substance-I-inactivatingaction. The biological activity of substance-I inactivatedby shaking with cell-free culture medium of the a mating typewas recovered by heating at 100?C, which destroyed the inactivatingaction of the culture medium with little effect on the substance-Iactivity, indicating that a substance in the culture mediuminactivated substance-I by binding to it. This is supportedby the fact that the inactivating action completely stoppedin 30 min, leaving a considerable amount of active substance-I,when the concentration of the inactivating substance was lowcompared with that of substance-I. The ability to produce thebinding substance as specific to the a mating type. The bindingsubstance was different from the a agglutination substance responsiblefor sexual agglutination. 2 On leave from Osaka City University. (Received April 6, 1977; )  相似文献   

18.
-Caprolactam-utilizing bacteria split -caprolactam, -valerolactamand -butyrolactam, and produce the -amino acids correspondingto them. This activity is lost when cells are grown on 6-amino-caproicacid or ammonium adipate, and reappears when cells are incubatedwith either -caprolactam or -valerolactam as the sole majororganic nutrient. Chloramphenicol inhibits this adaptation.The enzyme splitting those lactams is one and the same. It maybe called "lactam-splitting enzyme". But attempts to demonstratethe enzymic activity in a cell-free system has not yet beensuccessful. (Received September 9, 1965; )  相似文献   

19.
The euryhaline charophyte Lamprothamnium papulosum (Wallr.)J. Gr. was adapted to media with decreasing salinities rangingfrom 550 to 0 mosmol kg–1. Vegetative plants grown inmedia with osmotic pressures (0) in the range of 550 to 130mosmol kg–1 maintained a constant turgor pressure () at309 + 7 mosmol kg–1. The ions K+, Na+ and Cl–, werethe predominant solutes in the vacuole. Changes in their concentrationsaccount for the variation in internal osmotic pressure (1) with,0. The divalent ions Mg2+, Ca2+ and were also present in significant amounts, but their concentrationsdid not alter with changes in, 0. In cells subjected to hypo-osmotic shock the regulation of was incomplete. The turgor pressure increased from 302 to 383mosmol kg–1. The first rapid response to the sudden decreasein 0 was a loss of K+ and Cl. In contrast to the decreasein ionic concentrations an accumulation of sucrose occurredwhich could account for the increase of . The increase in sucroseconcentration started 24 to 48 h after the downshock and reachedits highest value after 3 to 4 weeks. The sucrose concentrationin the vacuole was up to 320 mol m–3. During this timethe ionic content continued to decrease but did not counterbalancethe sucrose concentration sufficiently to regain the original. High sucrose levels accompanied by an enhanced were also observedduring the period of fructification (sexual reproduction: formationof antheridia and oogonia) in Lamprothamnium kept under conditionsof constant salinity. It is concluded that high sucrose content and elevated arecharacteristic of sexual reproduction in this charophyte. Lamprothamniumis able to tolerate different during various developmentalstages (e.g. vegetative and reproductive phases). Key words: Lamprothamnium papulosum, sucrose, turgor pressure  相似文献   

20.
The indolo--pyrone fluorescence method was modified to measurethe endogenous amount of indole-3-acetic acid (IAA) in lettuceseedlings, because impurities in lettuce extracts made the indolo--pyronesolution turbid, if the reaction of the extracts with aceticanhydride to give indolo--pyrone was disrupted with 3 ml distilledwater. This turbid solution caused light scattering, resultingin overestimating the IAA amount in lettuce seedlings. We could,however, obtain a clear indolo--pyrone solution by disruptingthe reaction with 0.2 ml distilled water and 2.8 ml acetic acidin place of 3 ml distilled water. We examined the reliabilityof the new method and found that the use of acetic acid substantiallyslowed down the rate of indolo--pyrone breakdown and did notdecrease the sensitivity of the method. The effect of gibberellicacid on the endogenous amount of IAA in lettuce seedlings wasalso examined. 1 One of the authors (S. K.) received for this work a grantfrom Osaka City University to study abroad. (Received January 11, 1977; )  相似文献   

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