Properties of the Dicyclohexylcarbodiimide-Binding Subunit of Cytochrome c Oxidase from Sweet Potato

Subunit IV of cytochrome c oxidase from sweet potato was boundwith dicyclohexylcarbodiimide and synthesized in isolated mitochondria.Thus, this subunit corresponds to subunit HI of the analogousmammalian and fungal enzymes. Subunit IV was a mixture of twopolypeptides (subunits IVa and IVb) which differed slightlyin structure. ¹Present address: Research Institute of Molecular Genetics,Shimane University, Matsue, 690 Japan. ²Present address: Institute of Low Temperature Science, HokkaidoUniversity, Sapporo, 060 Japan.     

Degradation of Xyloglucan by Wall-Bound Enzymes from Soybean Tissue II: Degradation of the Fragment Heptasaccharide from Xyloglucan and the Characteristic Action Pattern of the {alpha}-D-Xylosidase in the Enzyme System

Hydrolysis of the fragment heptasaccharide (glucose : xylose= 4 : 3) from xyloglucan with an enzyme preparation from soybeancell wall produced a penta- and a trisaccharide. The resultsof fragmentation analysis of these oligosaccharides with Aspergillusoryzae ß-D-glucosidase indicate the following structuresfor the penta- and trisaccharide. The detection of these intermediate products suggested thatdegradation of the heptasaccharide took place by sequentialsplitting of the -D-xylosidic and ß-D-glucosidic linkages.A characteristic action pattern of the a-D-xylosidase in theenzyme preparation was found. ¹Present address: Department of Biology, McGill University,Montreal, Canada. ²Present address: Department of Botany, Iowa State University,Ames, Iowa 50010, U.S.A. (Received August 20, 1982; Accepted December 7, 1982)     

Localization and Binding Characteristics of a High-Affinity Binding Site for N--Acetylchitooligosaccharide Elicitor in the Plasma Membrane from Suspension-Cultured Rice Cells Suggest a Role as a Receptor for the Elicitor Signal at the Cell Surface

A high-affinity binding site for N-acetylchitooligosac-chlarideelicitor was found to localize in the plasma membrane from suspension-culturedrice cells. Binding kinetics as well as the specificity of thisbinding site corresponded well with the behavior of the ricecells to the editor. These characteristics suggest that thebinding site represents a functional receptor for N-acetylchitooligosaccharideelicitor in rice. ²Present address: Okinawa Prefectural Livestock ExperimentalStation, 2009-5 Shoshi, Nakijin-son, Okinawa, 905-04 Japan. ³Present address: School of Hygiene and Public Health, The JohnsHopkins University, 615 North Wolfe Street, Baltimore, Maryland,21205 U.S.A. ⁴Present address: University of Tenessee, Microbiology, knoxville,Tennessee, 37996 U.S.A.     

Phosphoenolpyruvate Carboxylase of Maize Leaves: an Improved Method for Purification and Reduction of the Inhibitory Effect of Malate by Ethylene Glycol and Bicarbonate

Light-adapted and dark-adapted forms of phosphoenolpyruvatecarboxylase were purified from maize leaves by an improved methodthat included chromatography on Butyl-Toyopearl in the presenceof ethylene glycol. The inhibition by malate was relieved notonly by increasing concentrations of ethylene glycol but alsoby bicarbonate at pH 7.0. ¹Present address: NEOS Central Research Laboratory, 1-1 Ohike-machi,Kosei-cho, Shiga, 520-32 Japan. ²Present address: Asahi Medical Co., Ltd., 4-3400-I Asahimachi,Nobeoka, 882 Japan. ³Present address: Chugai Pharmaceutical Co., Ltd., 1-135 Komakado,Gotemba, 412 Japan.     

Induction of Cytosolic Acetyl-Coenzyme A Carboxylase in Pea Leaves by Ultraviolet-B Irradiation

Levels of subunits of two acetyl-coenzyme A carboxylases werehigh in small leaves of Pisum sativum, decreased with growth,and remained constant in fully expanded leaves. Irradiationof fully expanded leaves induced the cytosolic isozyme only.This result suggests a key role for the cytosolic enzyme inprotection against UV-B. ¹Present address: Laboratory of Molecular Genetics, BiotechnologyInstitute, Akita Prefectural College of Agriculture, 2-2 Minami,Ohgata, Akita, 010-04 Japan ²Present address: Laboratory of Plant Molecular Biology, Schoolof Agricultural Sciences Nagoya University, Nagoya, 464-01 Japan     

Loss of the Photosynthetic Capacity and Proteins in Senescing Leaves at Top Positions of Two Cultivars of Rice in Relation to the Source Capacities of the Leaves for Carbon and Nitrogen

Senescing leaves are a source organ of both carbon and nitrogenbut, because degradation of chloroplast proteins and exportof their degradation products to sink organs give rise to lossof the photosynthetic capacity, the leaves serve as the sourceof nitrogen only at the cost of their source capacity for carbon.Changes in the photosynthetic capacity and levels of proteinsin leaves at the top four positions of two cultivars of rice,Nipponbare and Akenohoshi, during the ripening stage were investigatedtaking the trade-off relationship between the two source capacitiesinto consideration. Rate of light-saturated photosynthesis (Pmax)in leaves decreased more rapidly in Nipponbare than in Akenohoshiafter heading. Various proteins were also degraded during senescence,with Nipponbare leaves showing faster loss of proteins thanthe corresponding leaves of Akenohoshi. Decline in Pmax wascorrelated, similarly in the two cultivars, with losses of ribulose-l,5-bisphosphatecarboxylase/oxygenase, soluble proteins, chlorophyll a thatbound to the reaction center complexes of the two photosystems,the activity of whole-chain electron transport, and a majorpart of insoluble proteins during senescence. The results suggestthat degradation of proteins during senescence of rice leavesis coordinated so as to enable the leaves to perform photosynthesiswith a high use efficiency of protein and export nitrogen ata low or nearly minimum cost of the source capacity for carbon. ⁵ Present address: Section of Biology, University of California,Davis, California 95616, U.S.A. ⁶ Present address: Faculty of Agriculture, Utsunomiya University,350 Mine-machi, Utsunomiya, 321 Japan.     

Purification and characterization of uroporphyrinogen decarboxylase from tobacco leaves

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; )     

Comparison of carbon dioxide fixation and the fine structure in various assimilatory tissues of Amaranthus retroflexus L

The pattern for primary products of CO₂-fixation and the chloroplaststructure of Amaranthus retrqflexus L., a species which incorporatescarbon dioxide into C₄ dicarboxylic acids as the primary productof photosynthesis, were compared in various chlorophyll containingtissues,i.e., foliage leaves, stems, cotyledons and pale-greencallus induced from stem pith. Despite some morphological differencesin these assimilatory tissues, malate and aspartate were identifiedas the major compounds labelled during a 10 sec fixation of¹⁴CO₂ in all tissues. Whereas, aspartate was the major componentin C₄-dicarboxylic acids formed in foliage leaves, malate predominatedas the primary product in stems, cotyledons and the pale-greencallus. The percentage of ¹⁴C-radioactivity incorporated intoPGA and sugar-P esters increased and ¹⁴C-sucrose was detectedin the prolonged fixation of ¹⁴CO₂ in the light, not only infoliage leaves, but also in stems and cotyledons. ¹ This work was supported by a Grant for Scientific ResearchNo. 58813, from the Ministry of Education, Japan. ² Present address: Institute of Applied Microbiology, Universityof Tokyo, Tokyo, Japan. ³ Present address: Department of Biochemistry, University ofGeorgia, Athens 30601. Georgia, U. S. A. (Received July 10, 1971; )     

ORNITHINE CYCLE ENZYMES IN THE BLUE-GREEN ALGA NOSTOC MUSCORUM

Cell-free extracts of a bacteria-free culture of Nostoc muscorumwere used to demonstrate the occurrence of part of the KREBS-HENSELEITornithine cycle in blue-green algae. Evidence is presented forthe conversion of ammonia and bicarbonate to carbamyl phosphateand the coupling of carbamyl phosphate to ornithtne to yieldcitrulline. Attempts to demonstrate the conversion of citrullineto arginine were not successful. ¹Present address: Scripts Institute of Oceanography, Universityof California, La Jolla, California, U.S.A. ²Present address: Department of Biochemistry and Nutrition,The University of Texas Medical Branch, Galveston, Texas, U.S.A.     

The effect of barban on shoot formation in tobacco callus cultures

Shoot formation in tobacco callus was completely inhibited bythe presence of barban in the media during the first 2 daysof culture. Callus transferred to media containing barban from4th to the 12th day showed progressively less inhibition. Similarresults were obtained with GA₃. ¹Present address: Biology Department, Chung Chi College, TheChinese Univ. of Hong Kong, Shatin, N.T., Hong Kong ²Present address: Plant Hormone & Regulator Pioneering ResearchLab., U.S. Dept. Agric, Crops Res. Div., Beltsville, Md., U.S.A. (Received April 21, 1970; )     

Protein Synthesis Linked to Respiration and Phosphorylation in Intact Euglena Mitochondria

Highly purified condensed mitochondria obtained from bleachedmutant. W₁₀BSmL of Euglena gracilis Klebs var bacillaris Coriincorporate [³⁵S]methionine into protein when fortified withmalate, ADP, Mg²⁺, phosphate and a sucrose osmoticum. Twentyto twenty-five polypeptide bands were found to be labeled inorganello when the labeled protein was subjected to sodium dodecylsulfatepolyacrylamide gel electrophoresis. Methionine incorporation,but not respiration or oxidative phosphorylation, was blockedby chloramphenicol and other 70S ribosomal translation inhibitorsbut cycloheximide and ribonuclease were without effect. Inhibitorsof electron transport and uncouplers of oxidative phosphorylationwere excellent inhibitors of protein synthesis. Thus, thesemitochondrial preparations carry out protein synthesis in organellothat is linked to respiration and oxidative phosphorylation. ¹Present address: VA Hospital Outpatient Clinic, 17 Court St.,Boston, MA 02115, U.S.A. ²Present address: Laboratories de Microbiologia e Inmunologia,Universidad Catolica de Chile, Casilla 114-D, Santiago, Chile. ³Present address: Botany Department, University of Massachusetts,Amherst, MA 01003, U.S.A. (Received June 17, 1985; Accepted October 28, 1985)     

Changes in Levels of Phosphoenolpyruvate Carboxylase with Induction of Crassulacean Acid Metabolism in Mesembryanthemum crystallinum L.

Expanded leaves of Mesembryanthemum crystallinum L. performingC₃ photosynthesis were induced to perform pronounced Crassulaceanacid metabolism (CAM) by exposing the plant roots to higherNaCl concentration. Levels of phosphoenolpyruvate (PEP) carboxylaseactivity increased 10-fold during the 7-day induction period.Densitometric analysis of Coomassie-stained sodium dodecyl sulfate(SDS) polyacrylamide gradient slab gels of leaf extracts, preparedduring the course of CAM induction, revealed that at least fivebands of polypeptides increased in content (kilodalton valuesof 98, 91, 45, 41, 38). Higher levels of three additional polypeptides(kilodalton values of 102, 76, 33) became apparent after tissuehad been grown for 2 weeks at 400 mM NaCl. Of these polypeptides,that having a mass of 98 kilodaltons was identified as the subunitof PEP carboxylase by comparison with the corresponding bandfrom partially purified PEP carboxylase from the same tissue.Only a faint 98 kilodalton band was evident on SDS gels fortissue operating in the C₃ mode; staining intensity at thislocation increased with increasing NaCl-salinity in the rootingmedium until CAM was fully induced. These data provide evidencefor net synthesis of PEP carboxylase and several other proteinsduring the induction of CAM in M. crystallinum. ¹ Present address: USDA, P. O. Box 867 Airport Rd., Beckley,WV. 25801, U.S.A. ² Present address: Department of Botany, Washington State University,Pullman, Washington 99164, U.S.A. ³ Present address: Botanisches Institut der Universit?t, MittlererDallenbergweg 64, 8700 W?rzburg, W.-Germany. (Received October 27, 1981; Accepted March 15, 1982)     

Subcellular localization, of glucosyl transferases involved in lectin glucosylation in Pisum sativum seedlings

Cellular membranes from 4 to 5-days old etiolated pea seedlingswere isolated by isopyenic centrifugation. Marker enzymes wereused to measure the purity of the subcellular fractions. Theformation of dolichy!-P-glucose and of glucosylated lectin wastested in all the fractions. Both activities were associatedwith the endoplasmic reticulum fractions. When the membraneswere prepared in the presence of EDTA, a shift in both activitiesto a lower density in the gradient was observed. These results are in agreement with the current assumption thatglycosylation of proteins via lipid-linked sugars is a cotranslationalprocess. ¹ Present address: Centra de Investigaciones Agron?micas, INTA,C.C. 25, Castelar, Argentina. ² Present address: Department of Biochemistry, University ofMiami, P. O. Box 016129, Miami, FL 33101, U.S.A. ³ To whom correspondence should be addressed. Present address:Instituto de Investigaciones Biologicas, Universidad Nac. deMar del Plata, C. C. 1348, 7600 Mar del Plata, Argentina. (Received April 24, 1979; )     

A Short Lived Intermediate in the Photoconversion of Protochlorophyllide to Chlorophyllide a

The transient absorption change for the photoreduction of protochlorophyllide(PChlide) was studied with a solution of extracted PChlide holochromeand with etiolated leaves. The following results were obtained:(1) A short-lived intermediate with an absorption maximum at690 nm was found before formation of chlorophyllide a (Chlide).(2) The intermediate appeared instantly at the onset of theactinic laser, and it decayed very fast with a rate constantof 3.4 x 10⁵ sec^–1. (3) This decay constant for the intermediateagreed well with the rate constants for Chlide formation, 3.1x 10⁵ sec^–1 for the extract and 4.6 x 10⁵ sec^–1for the etiolated leaves. ¹Present address: Department of Botany, Faculty of Science,Kyoto University, Kitashirakawa, Kyoto 606, Japan. (Received September 24, 1980; Accepted December 6, 1980)     

Effects of Leaf Chilling on Thylakoid Functions, Measured at Room Temperature, in Cucumis sativus L. and Oryza sativa L.

Photosynthetic functions in leaves of cucumber (Cucumis sativusL.) and rice (Oryza sativa L.) were examined before and aftervarious chilling treatments. Cucumber leaves lost the capacityfor the photosynthetic oxygen evolution after chilling at 0°Cin the dark for 48 h. Thyla-koids isolated from such leaveswere not able to reduce dichloroindophenol (DCIP), but the additionof diphenylcarbazide (DPC), an electron donor to PS II, restoredthe ability to reduce DCIP, indicating that the site of damageis in the water-splitting machinery of PS II. In moderate light (500 jumol quanta m^–2s^–1), chillingof cucumber leaves at 5°C for 5 h was sufficient to inducethe complete loss of the capacity for photosynthetic oxygenevolution. Electron transport rates measured in thylakoids wereunaltered, but thylakoids were totally permeable to protons.Since the addition of dicyclohexylcarbodiimide (DCCD) restoredcoupling and the capacity for proton uptake, the primary siteof damage was deduced to be in the ATPase. In rice, both chilling treatments had barely any effect on thylakoidfunctions, although some negative effects was apparent in photosynthesisin leaves. ¹Present address: Department of Botany, Faculty of Science,University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113 Japan. ²Present address: Department of Botany, Duke University, Durham,NC 27706, U.S.A. (Received January 11, 1989; Accepted June 12, 1989)     

Lipoxidase in early growth of wheat

Lipoxidase activity in etiolated wheat seedlings grown for 3.5days was localized primarily in the coleoptile and first leafof the seedling with moderate activity in the germinated seedand root. After 7 days growth, the distribution of lipoxidasewithin the plant did not change markedly while the total activitydecreased. The dormant wheat seed exhibited 2 major and 2 minor bands oflipoxidase activity on polyacrylamide gel zymograms. After germination,there was a marked change in the relative intensities of the4 lipoxidase bands depending on the part of the seedling assayed. ¹ Supported in part by funds from the Agricultural ResearchService, U. S. Department of Agriculture Grant No. 12-14-100-7654(74)administered by the Western Utilization Research and DevelopmentDivision, Albany, California. Published with the approval ofthe Director of the Wisconsin Agricultural Experiment Station. ² Present address: U. S. Department of Agriculture, NorthernGrain Insects Research Laboratory, Brookings, South Dakota 57006,U.S.A. ³ Present address: Institute of Experimental Phytopathologyand Entomology, Ivanka Pri Dunaji, Czechoslovakia.     

Properties of S-adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase from barley

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; )