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1.
1. Uroporphyrinogen decarboxylase which catalyzes the formationof coproporphyrinogen from uroporphyrinogen is located in thesoluble fraction of tobacco leaves and was purified 72 foldthrough ammonium sulphate precipitation and calcium phosphosphategel absorption. 2. Kinetic studies indicated that the apparentMichaelis constant was 1 ? 10-6 M for uroporphyrinogen III (pH6.5; 37?C). Uroporphyrinogen III served as a much better substratethan uroporphyrinogen I under the standard conditions of thisstudy. 3. Enzyme activity was inhibited by thiol reagents andheavy divalent cations and was stimulated by some chelatingagents. 4. Both chloride and fluoride salts inhibited the formationof coproporphyrinogen from uroporphyrinogen.
1Present address: Department of Chemistry, Simon Fraser University,Burnaby 2, British Columbia, Canada.
2Present address: Biology Department, Utah State University,Logan, Utah 84322, U. S. A. (Received June 8, 1974; ) 相似文献
2.
Glycine decarboxylase and serine formation in spinach leaf mitochondrial preparation with reference to photorespiration 总被引:2,自引:0,他引:2
Glycine decarboxylation and serine synthesis were investigatedto account for photorespiratory CO2 evolution in higher plants.Glycine decarboxylase in leaf mitochondria was found to splitglycine into CO2, NH3 and a C1 unit. Free glyoxylic acid wasnot involved in this process as an intermediate. Serine synthesiswas closely related to decarboxylation of glycine. We inferredthat serine is formed from two molecules of glycine by the combinedaction of glcine decarboxylase and serine hydroxymethyltransferase.Glycine decarboxylation and serine synthesis were stimulatedby NAD, PALP and THFA, and were inhibited by detergents, lipase,sonication, mechanical treatment, thyroxine and thiol compounds,suggesting the importance of structural intactness of the mitochondrialmembrane system. Glycine decarboxylase was present in intacttissues in quantities consistent with glycolate production duringphotosynthesis. We concluded that glycine decarboxylase in mitochondriais principally responsible for CO2 evolution in photorespiration.A control mechanism of photorespiration is discussed based onthe stimulation of glycine decarboxylase by NAD and on inhibitionby NADH.
1 A part of this work was presented at the Annual Meeting (April,1969) of the Japanese Society of Plant Physiologists, Kanazawa,and at the annual Meeting (April, 1970) of the Japanese AgricultualChemical Society, Fukuoka. (Received August 3, 1970; ) 相似文献
3.
This study was designed to examine possible links between polyaminebiosynthesis and effects of growth regulatory compounds. Anauxin (IAA), a cytokinin [benzyladenine; benzylaminopurine (BAP)],an ethylene source (ethephon) and abscisic acid (ABA) were individuallyapplied to terminal buds of excised etiolated or red light (R)-exposedpea epicotyls. Effects were noted on bud fresh weight and onthe two main enzymes of putrescine biosynthesis, arginine decarboxylase(ADC; EC 4.1.1.19
[EC]
) and ornithine decarboxylase (ODC; EC 4.1.1.17
[EC]
).As previously reported [Dai and Galston (1981) Plant Physiol.67: 266], both bud growth and ADC activity are increased byR light. In such buds, ADC is raised further by 110 µMBAP or ABA and inhibited by 110 µM IAA or ethylene(50 mg/liter or more of ethephon). In all cases, effects ofR-irradiation plus 1 mM growth regulators on ODC activity wasthe inverse of their effects on ADC, indicating independentcontrol of these pathways. These results do not support theview that putrescine biosynthetic activity is correlated withgrowth in etiolated pea seedlings.
1Supported by a grant from NSF to A.W.G.
2Supported by a grant from the Turkish Government. Permanentaddress: Department of General Botany, University of Istanbul,S?leymaniye, Istanbul, Turkey.
3On sabbatical leave from the Department of Horticulture, HebrewUniversity of Jerusalem, Rehovot, Israel. (Received September 22, 1983; Accepted February 28, 1984) 相似文献
4.
Stephen Rawsthorne Christopher M. Hylton Alison M. Smith Harold W. Woolhouse 《Planta》1988,173(3):298-308
Photorespiratory metabolism of the C3-C4 intermediate species Moricandia arvensis (L.) DC has been compared with that of the C3 species, Moricandia moricandioides (Boiss.) Heywood. Assays of glycollate oxidase (EC 1.1.3.1), glyoxylate aminotransferases (EC 2.6.1.4, EC 2.6.1.45) and hydroxypyruvate reductase (EC 1.1.1.29) indicate that the capacity for flux through the photorespiratory cycle is similar in both species. Immunogold labelling with monospecific antibodies was used to investigate the cellular locations of ribulose 1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), glycollate oxidase, and glycine decarboxylase (EC 2.1.2.10) in leaves of the two species. Ribulose 1,5-bisphosphate carboxylase/oxygenase was confined to the stroma of chloroplasts and glycollate oxidase to the peroxisomes of all photosynthetic cells in leaves of both species. However, whereas glycine decarboxylase was present in the mitochondria of all photosynthetic cells in M. moricandioides, it was only found in the mitochondria of bundle-sheath cells in M. arvensis. We suggest that localized decarboxylation of glycine in the leaves of M. arvensis will lead to improved recapture of photorespired CO2 and hence a lower rate of photorespiration.Abbreviations kDa
kilodalton
- RuBP
ribulose-1,5-bisphosphate 相似文献
5.
1. The effects of "carbonyl" reagents on the photosyntheticin-corporation of 14CO2 into the assimilation products of tobaccoand spinach leaves were studied. The presence of "carbonyl"reagents causes an increase in the ratio of 14CO2 incorporatedin glycine and a decrease in serine. The incorporation of 14Cfrom glycolate-1-14C and glycolaldehyde-2-14C into glycine andserine was also affected by "carbonyl" reagents, as in the caseof 14CO2-experiment. 2. The feeding experiments of glycine-1-14C and serine-1-14Cin the presence and in the absence of "carbonyl" reagents revealedthat these reagents inhibit the conversion of glycine to serine. 3. The results obtained above, together with the effects ofthiols on 14CO2 incorporation presented in this paper, supportthe assumption that glycine and serine are formed via glycolateand glyoxylate during photosynthesis in green plants. 4. Comparison of 14C incorporation in malate from 14CO2, glycolate-1-14C,glycine-1-14C and serine-1-14C in the presence and in the absenceof "carbonyl" reagents suggested the occurrence of the pathwayof the malate formation via glycolate and glyoxylate, not passingthrough glycine and serine, during photosynthesis.
1 A part of this paper was presented at the Symposium on "Nitrogenand Plant" by the Japanese Society of Plant Physiologists, inOctober, 1963
2 Present address: Radiation Center of Osaka Prefecture, Sakai,Osaka 相似文献
6.
A novel photorespiratory mutant of Arabidopsis thaliana, designatedgld2, was isolated based on a growth requirement for abnormallyhigh levels of atmospheric CO2. Photosynthetic CO2 fixationwas inhibited in the mutant following illumination in air butnot in atmosphere containing 2% O2. Photosynthetic assimilationof 14CO2 in an atmosphere containing 50% O2 resulted in accumulationof 48% of the soluble label in glycine in the mutant comparedto 9% in the wild type. The rate of glycine decarboxylationby isolated mitochondria from the mutant was reduced to 6% ofthe wild type rate. In genetic crosses, the mutant complementedtwo previously described photorespiratory mutants of A. thalianathat accumulate glycine during photosynthesis in air due todefects in glycine decarboxylase (glyD, now designated gld1)and serine transhydroxymethylase (stm). Because glycine decarboxylaseis a complex of four enzymes, these results are consistent witha mutation in a glycine decarboxylase subunit other than thataffected in the gld1 mutant. The two gld loci were mapped tochromosomes 2 and 5, respectively.
3Present address: Department of Crop and Soil Sciences, MichiganState University, East Lansing, MI 48824, U.S.A.
4Present address: Department of Applied Bioscience, Facultyof Agriculture, Hokkaido University, Kita-Ku, Sapporo, 060 Japan
5Present address: Department of Biology, Carnegie Institutionof Washington, 290 Panama Street, Standford, CA 94305, U.S.A. 相似文献
7.
Relationships among the activities of enzymes related to photosynthesisand photorespiration, and 14CO2 photosynthetic products wereinvestigated with individual tobacco leaves attached to thestalk from the bottom to the top. P-glycolate phosphatase ofthe chloroplasts and glycolate oxidase of the peroxisomes hadtheir maximum activities in the 25th leaf from the dicotyledons.Maximum photorespiration was similarly distributed. The highestratio of serine-14C to glycine-14C in the photosynthesates andmaximum glycolate formation were also observed in the 25th leaf.Glutamateglyoxylate aminotransferase, serine hydroxymethyltransferaseand glycine decarboxylase were more active in the upper leaves.RuDP carboxylase had nearly constant activity in all leaves,except for the youngest in which activity decreased. MaximumCO2 photosynthesis and enzyme activity for the C4 dicarboxylicacid cycle occurred in the upper, youngest leaf. Distributionof photosynthetic CO2 fixation among the leaves did not coincidewith RuDP carboxylase activity. The photosynthetic capacityappeared to be better related to the distribution pattern forenzymes of the C4 dicarboxylic acid pathway, i.e. PEP carboxylase,pyruvate Pi dikinase and 3-PGA phosphatase in the upper leaves.The results suggest that the C4 dicarboxylic acid pathway participates,to some extent, in photosynthesis in young leaves of tobacco,a dicotyledonous plant.
1This work was reported at the Annual Meeting (1970) of theJapanese Plant Physiologists in Kobe.
2The Central Research Institute, Japan Monopoly Corporation1-28-3, Nishishinagawa, Shinagawaku, Tokyo, 141 Japan. (Received November 2, 1972; ) 相似文献
8.
Collapse of Peroxide-Scavenging Systems in Apple Flower-Buds Associated with Freezing Injury 总被引:2,自引:0,他引:2
Changes in the metabolic activities of peroxide-producing systemsand peroxide-scavenging systems after freezing and thawing inflower buds of the apple, Malus pumila Mill., were studied withspecial reference to freezing injury. In flower buds of theMcIntosh apple that were frozen below lethal temperatures,the activity of NADH-Cyt c reductase (EC 1.6.99.3
[EC]
), one of theenzymes in the electron-transport chains that are related tothe peroxide-producing systems, decreased slightly, while thatof Cyt c oxidase (EC 1.9.3.1
[EC]
) hardly changed. By contrast, theactivities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49
[EC]
),dehydroascorbate reductase (EC 1.8.5.1
[EC]
) and ascorbate peroxidase(EC 1.11.1.11
[EC]
), which are involved in the peroxide-scavengingsystems, decreased to very low levels. The activity of glyceraldehyde-3-phosphatedehydrogenase (EC 1.2.1.12
[EC]
) also decreased markedly. However,little change was observed in the activities of hexokinase (EC2.7.1.1
[EC]
), glucosephosphate isomerase (EC 5.3.1.9
[EC]
), glutathionereductase (EC 1.6.4.2
[EC]
) and glutathione peroxidase (EC 1.11.1.9
[EC]
).Examination of substrates involved in the peroxide-scavengingsystems revealed that the levels of glucose-6-phosphate andfructoses-phosphate decreased to approximately 104 to105 M and 105 M, respectively, and the levelsof GSH decreased to about 105 M or became barely detectable.A decrease in the levels of GSSG also occurred while levelsof ascorbate rose slightly. Similar results were observed withflower buds from Starking Delicious and Jonathanapple trees. These results suggest that the freezing injury to apple flower-budsis closely related to the collapse of the peroxide-scavengingsystems that are coupled with the pentose phosphate cycle. Theresults also suggest that the dysfunction of these peroxide-scavengingsystems is caused by H2O2, which may be produced during freezingand thawing. (Received March 14, 1992; Accepted June 5, 1992) 相似文献
9.
Growth of Vicia faba seedlings is accompanied by a rapid increasein arginine decarboxylase (EC 4.1.1.19
[EC]
) in the leaves and epicotyl.Increased enzyme activity was observed under saline conditionsin the presence of NaCl and with osmotic stress by mannitol.The partially purified enzyme (about 86-fold) readily decarboxylatedL-arginine, while D-arginine, L-homoarginine, L-ornithine andL-lysine were decarboxylated very slowly, and L-citrulline andL-glutamic acid were not decarboxylated. The Km value was 5.8?104M for L-arginine. The optimal pH and temperature for activitywere 8.5 and 45?C, respectively. p-Chloromercuribenzoate andN-ethylmaleimide were effective inhibitors of the enzyme. Inhibitionby spermidine, putrescine and agmatine suggested a possiblefeed-back mechanism in the pathway of polyamine biosynthesis. (Received October 11, 1983; Accepted February 24, 1984) 相似文献
10.
The effects of temperature lowering on the steady state chlorophyllfluorescence of leaves was investigated. Leaves from chill-sensitivespecies responded to a greater degree than did leaves from chill-resistantspecies. Arrhenius plots of fluorescence change vs temperatureyielded a straight line with no breaks that would have indicateda membrane lipid phase change. We measured the fluorescencechanges at high and low excitation intensitites and monitoredfluorescence at 690 and 735 nm. The low temperature inducedfluorescence increase and the ratio of 690 to 735 nm fluorescencewere generally greater at lower light intensities. Treatmentwith DCMU reduced the effects of temperature on fluorescence.However, the effect of low intensity pulsing light on the fluorescenceyield of DCMU-treated leaves proved to be temperature dependent.At a low pulse rate (2 msec pulse, 5 pps) a logarithmic increasein fluorescence as a function of temperature was noted. Chill-sensitivespecies proved to be more responsive than chill-resistant species.Slight differences between hardened and unhardened materialwere noted. While the causal factors for the differential sensitivityof species to temperature lowering were not investigated, fluorescencemonitoring has proved to be a convenient and accurate methodfor investigating chill-sensitivity in leaves.
1 Contribution from the Missouri Agricultural Experiment Station.Journal Series Number 7791.
2 Present address: Florigen Greenhouses, 1351 E. Silver LakeRoad, Traverse City, Michigan 49684, U.S.A.
3 Present address: Department of Forestry, Iowa State University,Ames, Iowa 50011, U.S.A. (Received March 14, 1977; ) 相似文献
11.
S-Adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase(EC 2.1.1.11
[EC]
) is present in greening barley seedlings associatedwith the particulate fraction. This enzyme was purified 20 foldusing protamine and ammonium sulfate precipitation. The enzymewas active over a wide pH range with highest activity at pH7.5. The Km values for Mg-protoporphyrin IX and S-adenosylmethioninewere 48 and 39 µM, respectively; S-adenosylethionine andS-adenosyihomocysteine were competitive inhibitors with respectto S-adenosylmethionine; hemin inhibition was non-competitivewith respect to Mg-protoporphyrin IX; thiol compounds exhibiteda stimulatory effect on enzyme activity. The properties of theenzyme are discussed and compared with the enzyme from otherorganisms.
1 This research was supported in part by the Utah State AgriculturalExperiment Station.
2 Present address: Department of Chemistry, Boston University,Boston, Massachusetts, U. S. A.
3 Present address: Department of Biochemistry and Microbiology,Faculty of Pharmacy, Comenius University, Bratislava, Czechoslovakia. (Received February 20, 1978; ) 相似文献
12.
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
13.
Glycine as a substrate for photorespiration 总被引:1,自引:0,他引:1
Substrates for photorespiration were examined by feeding 14Clabeled compounds to tobacco and corn leaf segments and by measuring14CO2 evolution in light and darkness. CO2 release in the darkwas rapid, but in light CO2 release was slow due to refixationby photosynthesis. Carboxyl labeled glycine was more rapidlydecarboxylated than were glyoxylate, glycolate or serine. Hydroxypyridinemethanesulfonate, an inhibitor of glycolate oxidase, blocked CO2 releasefrom glycolate but not from glycine. Isonicotynyl hydrazideblocked CO2 release from both glycine and glycolate. DCMU blockedphotosynthetic refixation of the released CO2, consequentlythe rates of CO2 release in light and dark were about equal.It was concluded that CO2 release during photo-respiration camefrom the conversion of 2 molecules of glycine to one serineand one CO2. 14CO2 release from glycine-l-14C in the dark or with DCMU inlight can be used as an assay for photorespiration ability. CO2 release from glycine and glycolate by corn leaf segmentsin the dark proceeded at the rate of that in normal tobaccoleaf. This result, together with other work on O2 exchange andenzymatic analysis, indicates that corn and other plants docarry on photorespiration, but it is not manifested by CO2 releasein light. A yellow tobacco mutant, Consolation 402, had high rates ofphotorespiration by the 14CO2 assay, nearly half (or more) asmany peroxisomes as chloroplasts, and high rates of CO2 releasefrom glycine-l-14C or glycolate-l-14C. A common tobacco, BrightYellow, had lower rates of photorespiration, fewer visible peroxisomes,and slower decarboxylation of glycine and glycolate. The amount of 14CO2 release from glycine-l-14C or glycolate-l-14Cincreased only slightly when the temperature was raised from25 to 35°C.
1Parts of this work were abstracted at the Annual Meeting (April,1969) of Japanese Society of Plant Physiologists, Kanazawa
2Department of Biochemistry, Michigan State University, EastLansing, Michigan, U.S.A. (Received September 3, 1969; ) 相似文献
14.
- Formyltetrahydrofolate synthetase (E. C. 6. 3. 4. 3) was foundto be widely distributed in higher plants and the high enzymeactivity was observed in green leaves of Brassica and Alliumspecies, spinach, and in pea seedlings. In pea seedlings, theenzyme activity changed during the course of germination, andmost of the enzyme activity was located in a soluble fractionof the cytoplasm.
- The enzyme was labile and lost the activityrapidly, even whenstored at 5 in the presence of 0.1 M mercaptoethanol.It was,however, found that ammonium sulfate was very effectivein stabilizingthe enzyme activity.
- The enzyme has been purifiedapproximately 500-fold from extractsof pea seedlings by treatmentswith ammonium sulfate, protaminesulfate, hydroxylapatite, calciumphosphate gel, and DEAE-cellulosecolumn chromatography.
- Thepurified enzyme was specific for formate, ATP and FAH4,andthe Michaelis constants for these reactants were 2.1 102M, 5.1 104 M, and 5.6 103 M, respectively.
- The optimum pH was found to be 8.0, and the optimal temperaturewas observed at 37. Both NH4$ and a divalent cation (MgSS orMnSS) were required for the optimal activity.
15.
Plastid Development in Primary Leaves of Phaseolus vulgaris: THE EFFECTS OF BRIEF FLASHES OF LIGHT ON DARK-GROWN PLANTS 总被引:2,自引:0,他引:2
BRADBEER J. W.; CLIJSTERS H.; GYLDENHOLM A. O.; EDGE H. J. W. 《Journal of experimental botany》1970,21(2):525-533
Exposure of dark-grown beans to 1 ms flashes of light (2 ? 1014quanta/cm2/flash) at 15-min intervals induced growth of theprimary leaves as shown by increases in fresh weight, dry weight,and total protein. Effects of the flashes on plastid size andfine structure were not obvious until leaf growth was more thanhalf completed, when the prolamellar bodies became consumedand thylakoids were formed. Leaf samples taken after 638 and922 flashes contained some mesophyll cells with plastids ofabnormal appearance which had structures resembling stromacentrefibrils. Flashes of light increased both the chlorophyll content of theleaves and the activities seven enzymes of the photosyntheticcarbon cycle and of NAD-linked triosephosphate dehydrogenase(EC 1.2.1.12
[EC]
), these changes being correlated with leaf growthrather than the plastid changes detected by electron microscopy.There was only a small increase in the activity of phosphoribulokinase(EC 2.7.1.19
[EC]
) and no change in the activity of phosphopyruvatecarboxylase (EC 4.1.1.31
[EC]
). 相似文献
16.
In order to learn how the methyl group of S-methylcysteine wasmetabolized and its carbon was incorporated into the methylester of pectin in Chinese cabbage, leaves were fed S-methylcysteinewhich was labeled in the methyl group with both 3H and 14C.Incorporation of the radioactive isotopes into S-adenosylmethioninewas detected with little reduction in the 3H/14C ratio betweenthe methyl groups. The changes in the 3H/14C ratio between thepectin methyl ester recovered from the leaves and the S-methylcysteinefed to them indicate that there are at least two pathways inthe transfer of the methyl-carbon from S-methylcysteine to themethyl ester of pectin: one is the intact methyl group transfer,probably through S-adenosylmethionine, and the other is carbontransfer after the degradation of the methyl group. Cysteinesulfoxide lyase (EC 4.4.1.4
[EC]
) was found in the leaves and rootsin Chinese cabbage and its involvement in the methyl-carbontransfer is discussed. (Received December 8, 1975; ) 相似文献
17.
Purification of NADP-Malic Enzyme and Phosphoenolpyruvate Carboxylase from Sugar Cane Leaves 总被引:1,自引:0,他引:1
A procedure is described for the purification of phosphoenolpyruvatecarboxylase (EC 4.1.1.31
[EC]
) and NADP-dependent malic enzyme (EC1.1.1.40
[EC]
) from sugar cane leaves. Each enzyme was purified tohomogeneity as judged by sodium dodecyl sulfate-polyacrylamidegel electro-phoresis, with about 30% yield. Phosphoenolpyruvatecarboxylase was purified 54-fold. A molecular weight of 400,000and a homotetrameric structure were determined for the nativeenzyme. The purified carboxylase had a specific activity of20.0 {diaeresis}mol (mg protein)1 min1, and wasactivated by glucose-6-phosphate and inhibited by L-malate.Km values at pH 8.0 for phosphoenolpyruvate and bicarbonatewere 0.25 and O.l0 mM, respectively. NADP-malic enzyme, 356-foldpurified, exhibited a specific activity of 71.2 {diaeresis}mol(mg protein)1 min1 and was characterized as ahomotetramer with native molecular weight of 250,000. Purifiedmalic enzyme showed an absolute specificity for NADP+ and requireda divalent metal ion for activity. Km values of 0.33 and 0.008mM for L-malate and NADP+, respectively, were determined. Thisenzyme was inhibited by several organic acids, including ketoand amino acids; while succinate and citrate increased the enzymeactivity when assayed with 10{diaeresis}M L-malate. The effectsshown by amino acids and by citrate were dependent on pH, beinghigher at pH 8.0 than at pH 7.0. (Received October 26, 1988; Accepted February 3, 1989) 相似文献
18.
Allozyme variation of a Mysella tumida population in PatriciaBay, B.C., Canada was investigated at the phosphoglucomutase(PGM) locus. Seven alleles were detected. The observed frequencyof allelic combinations did not differ significantly from randommating expectations (0.25 < P < 0.50), however, heterozygositylevels were slightly greater than expected (Selander's D = 0.022).These results, together with previous work on the M. tumidareproductive cycle, indicate that natural populations of thisbivalve rarely, if ever, self-fertilize.
*Present Address: Friday Harbor Laboratories, University ofWashington, Friday Harbor, WA 98250, U.S.A.
**Present Address: Museum of Zoology, University of Michigan,Ann Arbor, M1 48109, U.S.A. (Received 30 December 1986; 相似文献
19.
Mahan James R.; Sherman Timothy D.; Funkhouser Edward A. 《Plant & cell physiology》1988,29(4):735-737
The thermal dependence of two of the reactions catalyzed bythe nitrate reductase from Chlorella vulgaris was determined.The activation energies for NADH:nitrate oxidoreductase (EC1.6.6.1
[EC]
) and NADH:Cytochrome c oxidoreductase (EC 1.6.99.3
[EC]
)are 42.1 kJ?mol1 and 21.5 kJ?mol1, respectively.Since the thermal dependency of the two enzymes is different,ratios of the activities will vary with temperature. The importanceof both rigorous thermal control during nitrate reductase assaysas well as the need to specify the temperature at which theratio of activities for the enzyme are clearly established.
1Present Address: Cropping Systems Research Laboratory, USDA-ARS,Route 3, Box 215, Lubbock, TX 79401, U.S.A. (Received November 25, 1987; Accepted March 2, 1988) 相似文献
20.
The metabolic transformation of glycine into serine in the photosyntheticbacterium Chromatium vinosum was accompanied by the evolutionof CO2 due to decarboxylation of glycine. Isonicotinylhydrazideinhibited both 14CO2 evolution and the formation of 14C-serinefrom 14C-glycine. The results indicate that a glycine-serinetransformation reaction takes place which is analogous to thatoccurring in green leaf tissues. Glycine may be metabolisedthrough serine by this reaction. The light stimulation of 14CO2evolution and 14C-serine formation from 14C-glycine by the Chromatiumcells are judged to be results of the light-induced enhancementof 14C-glycine uptake by the bacterial cells.
1This is paper 53 in the series "Structure and Function of ChloroplastProteins" and paper 7 of the series "Biosynthetic Mechanismof Glycolate in Chromatium". Paper 6 of the latter series isRef. 3 by Asami and Akazawa (1978).
2This study was aided by research grants from the Ministry ofEducation, Science and Culture of Japan and the Nissan ScienceFoundation (Tokyo).
3Postdoctoral Fellow (1980) of the Japan Society for the Promotionof Science. (Received May 20, 1980; ) 相似文献