bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymic Properties of Purified Myrosinase from Lepidium sativum Seedlings
Authors: Durham Paul L. , Poulton Jonathan E. 
Published: August 2018

Abstract
To establish the substrate specificity of the thioglucoside glucohydrolase myrosinase (EC 3.2.3.1), this enzyme was purified to homogeneity from light-grown cress (Lepidium sativum L.) seedlings by Sephadex gel filtration. Red Dye and anion exchange (FPLC Mono Q) chro­matography, and preparative isoelectric focusing. Hydrolytic activity was shown toward only 4 of the 29 synthetic and natural O-and S-glycosides tested. Highest activity was displayed with the endogenous glucosinolates benzylglucosinolate (Km, 295 μM) and sinigrin (Km, 300 μM) at an optimum pH of 5.5 in sodium citrate buffer. The synthetic glycosides PNPG (Km, 2.0 mM) and ONPG were poorer substrates at an optimum pH of 6.5 in potassium phos­phate buffer. The enzyme was inactive with all other nitrophenyl glycosides tested including PNP-a-D-glucoside and PNP-thio-β-D-glucoside, suggesting a requirement for O-β-D-glucose as the glycone moiety within these substrates. PNPG hydrolysis was stimulated 2.6-fold by ascorbate (1 mM). The enzyme exhibited no metal ion requirement and was strongly inhibited by lead nitrate, mercury chloride, and ferric chloride at 1 mM concentration. The metal chela­tors DIECA , EDTA , o-phenanthroline, and 2,2′-dipyridyl were not inhibitory, but the thiol reagents PCMS, PCMB, and N-ethylmaleimide (at 1mM) caused 50 -80% inhibition of enzyme activity.
Studies on the Biosynthesis of γ–Decalactone in Sporobolomyces odorus
Authors: Albrecht Wolfgang , Tressl Roland 
Published: August 2018

Abstract
Incubation of racemic ethyl [2,2-2H2]-(E)-3,4-epoxydecanoate and the corresponding acid with intact cells of Sporobolomyces odorus led to the formation of deuterium labeled γ-decalaetone. The detection of labeled 2-decen-4-olide and 4-oxodecanoic acid made it possi­ble to propose the biogenetic sequence leading to γ-decalactone. The determination of the en­ antiomeric ratio of the lactone revealed an unspecific metabolism of the precursor. In contrast to the (E)-isomer, after administration of ethyl [5,6-2H2]-(Z)-3,4-epoxydeeanoate no transfor­mation could be detected. These results indicate that (E)-3,4-epoxydecanoic acid, formed from (E)-3-decenoyl-CoA , an intermediate of the β-oxidation of linoleic acid, is the genuine precur­sor in the biosynthesis of γ-decalactone.
Carnivora: The Amino Acid Sequence of the Adult European Mink (Mustela lutreola, Mustelidae) Hemoglobins
Authors: Ahmed Aftab , Jahan Meeno , Braumtzer Gerhard 
Published: August 2018

Abstract
The complete amino acid sequences of the hemoglobins from the adult European mink (Mustela lutreola) are presented. The erythrocytes contain two hemoglobin components and three globin chains. The isolation of globin chains achieved by ion-exchange chromatography on a column of CM -cellulose in 8 M urea buffer. The primary structure of globin chains and of the tryptic peptides determined in liquid-and gas-phase sequenators. The alignment of the a-and β-chains with those of reported sequences from other carnivora species belonging to the family Mustelidae may give an insight into the evolution of this molecule.
Influence of High Steady Magnetic Fields on the Electrical Activity of the Electric Fish Apteronotus
Authors: Stojan L. , Sperber D. , Dransfeld K. 
Published: August 2018

We have investigated the influence of strong dc. magnetic fields - ranging up to 10 Tesla - on the weak sinusoidal electric signals which the electro-fish Apteronotus is known to emit. We made the following observations:
1. The amplitude of the sinusoidal electric signals rises with the application of the dc. magnetic fields, increasing by about 8% in a field of 10 Tesla.
2. The frequency of the signals of about 570 Hz was not at all affected by the field but remained constant in fields up to 10 Tesla.
Since the electric signals of Apteronotus are of neural origin our experiments indicate an influence of strong dc. magnetic fields on the nervous system of this electric fish.
Effect of Antisera to RuBP-Carboxylase/Oxygenase of TV. tabacum and Spinacia oleracea on the Oxygenase-Function of the Enzyme
Authors: Beuttenmüller M. , Nespoulous C. , Radunz A. , Schmid G. H. 
Published: August 2018

Abstract
In the present paper we demonstrate that the conformational state of the Afunctional enzyme ribulose-1,5-bisphosphate carboxylase oxygenase is different in the tobacco mulanl Susu when compared to the wild type tobacco or spinach. The conformational state of the tobacco mu- tant enzyme is characterized by the presence of a higher number of antigenic determinants ac- cessible to antibody binding. This seems to be correlated to a higher oxygenase activity in the mutant. The Afunctional enzyme ribulose-1,5-bisphosphate carboxylase oxygenase of the wild type tobacco Nicotiana tabacum var. John William’s Broadleaf, of the tobacco mutant Su.su and of spinach (Spinacia oleracea) was characterized by comparative immunological methods. Although the enzyme of the tobacco mutant appears identical to the enzyme of the wild type, when analyzed in immunodiffusion tests and immuno electrophoretical analyses, it exhibits a higher oxygenase activity. On the other hand the spinach enzyme exhibits only par- tial serological identity to the two tobacco enzymes. For the comparative studies pure IgG-fractions were prepared from the respective antisera. RuBP-carboxylasc oxygenase was used as a 70% purified enzyme preparation. Determination of the antibody binding capacity showed that the enzymes bind from the homologous antisera the highest amount of antibodies, which means that the antisera reflect the complementary picture of the enzyme structure. The enzyme molecules of N. tabacum var. JWB and of spinach bind 9 antibody molecules each. I lowevcr, the binding capacity of the tobacco mutant enzyme exhibiting the higher oxygenase activity is 30% higher. Measurement of the oxygenase function under the influence of the homologous as well as of the non-homologous antisera has led to the result that the oxygenase activity of all enzymes is inhibited. However, it is the degree of inhibition which differs. The antiserum to the mutant enzyme causes with the spinach as well as with the JWB-enzyme a higher degree of inhibition than that produced by the homologous antiserum. Therefore, a correlation between inhibitory effect brought about by this antiserum and the amount of antibodies bound does not exist. Whereas the enzyme of the tobacco wild type binds 20% less antibodies out of this antiserum its oxygenase activity is 60% more inhibited and the function of the spinach enzyme is 20% stronger inhibited although binding of antibodies from the antiserum to the tobacco enzyme is 50% lower. These observations permit the conclusion that the antiserum towards the mutant enzyme contains more antibodies with a higher binding affinity towards reactive regions of the oxy- genase function. This in turn means that the structure of this enzyme or its conformation must be different in comparison to the wild type enzyme.
Characterization of RuBP Carboxylase/Oxygenase of the N. tabacum Mutant Series "Consolation" with Homologous and Non-Homologous Antisera
Authors: Georgi S. , Radunz A. , Schmid G. H. 
Published: August 2018

Abstract
The molar ratio of RuBP carboxylase/oxygenase to the CF1 complex was determined in the wild type N. tabacum var. JWB and in various N. tabacum mutants, which differ with respect to their chloroplast structure and their photosynthetic and photorcspiratory activity. It appears that the ratio RuBP carboxylase oxygenase, CF1 is not constant in the different mutants, and apparently depends on the chloroplast structure and the photosynthetic capacity. In the green phenotypes of N. tabacum var. Consolation, var. NC 95 and var. Xanthi. whose lamellar system consists of a balanced ratio of grana and intcrgrana regions the ratio is 3-4 RuBP car- boxylase/oxygenase molecules per CF1 complex. In chloroplasts of the yellow-green mutant Su/su, and the yellow mutant of N. tabacum var. Consolation, whose lamellar system consists of extended intergrana regions and low stacked grana the RuBP carboxylase oxygcnasc/CF1 ratio is reduced to about one half. The aurea mutant A. tabacum Susu var. aurea and the yel- low-green leaf patches of variegated tabacum var. Xanthi arc characterized by the fact that one molecule RuBP carboxylase oxygenase correlates to two CF1 complexes. Also in the two N. tabacum mutants Su/su and Consolation green, that exhibit a 30% higher photorespiration these molar ratios depend on the chloroplast structure. The determination of the maximal binding of antibodies out of homologous and non-homo- logous antisera onto RuBP carboxylase oxygenase of the N. tabacum mutant Consolation showed, that the enzyme of the green mutant, which exhibits a higher oxygenase activity, has in comparison to the yellow-green and yellow phenotype of this mutant series and also in comparison to the wild type a 30 per cent higher antibody binding capacity. These differences in antibody binding arc shown in both the region of enzyme antibody equivalence and that of antibody excess. With the methods of enzyme-antibody precipitation in agarose gels these differences of enzymes, exhibiting higher or lower oxygenase activities, cannot be detected. The native enzymes and the large subunits of the enzyme of the three Consolation mutants yield in these test reactions with the enzyme of the wild-type fusing precipitation bands. Treatment with the chemical agent hydroxylamine. as well as heat treatment at 50 °C alters the enzyme conformation to such an extent that the antibody binding capacity is increased by 70%. The difference in the higher antibody binding capacity of the enzyme of the green mutant of N. tabacum var. Consolation is maintained also after these chemical modifications.
Quantitative Determination of the Distribution between Two Photosystem II-Mediated Oxidation Reactions in Oscillatoria chalybea: A Comparison between Water Oxidation and Hydrogen Peroxide Decomposition
Authors: Bader K. P. , Schmid G. H. 
Published: August 2018

Abstract
Mass spectromctric analysis reveals that oxygen evolution measured as the consequence of short saturating light flashes in thylakoid preparations of the filamentous cyanobacterium Oscillatoria chalybea consists of two portions, one coming from photosynthetic water splitting and one coming from H2O2 decomposition. This H2O2 decomposition is photosystem II-mediated and it is the S-state system which oxidizes H2O2 to give protons and oxygen. Water is neither intermediate nor seems it to be the origin of the reaction. At the high oxygen partial pressure of normal air H2O2 production and its decomposition exceeds manyfold the H2O splitting reaction. H2O2 production seems to come from photosystem II but is not necessarily produced on the acceptor side of photosystem II in the sense of a Mehler type reaction. From the reaction rate and the observed labeling density, it is inferred that production and decomposition must take place within the same reaction site which might be for both, the production and decomposition, the S-state system. In this sense. H2O2 might be the product of the S-state system and seems somehow associated with S2 or S3. Thus, if oxygen evolution is measured as the consequence of short saturating light flashes in an ambient atmosphere of 21% oxygen, mass spectrometry reveals a flash pattern which bears the oxygen label of the ambient atmosphere and which has not much in common with an usual Kok sequence. Such a pattern might start in the first three flashes more or less as a Kok pattern would, but is then in the pattern portion usually characteristic for steady-state oxygen evolution characterized by a periodicity of two indicating that H2O2 decomposition requires only two light quanta. At high oxygen partial pressure (e.g. in 21% ,16O2) both reaction portions can be quantitatively deter- mined by labeling the assay with H2
18O and measuring the evolved (16O::18O)/18O2 ratio which is representative for water splitting. The measured evolution of 16O2 (mass 32) represents H2O2 decomposition, if the 16O2 portion calculated from the measured mass 34/36 ratio is subtracted. At low oxygen partial pressure the H2O2 forming and decomposing reaction is largely sup- pressed and oxygen evolution from water-splitting prevails. As a hypothesis, H2O2 production and its decomposition might be a defective performance of photosystem II at high ambient oxygen partial pressure in these cyanobacteria, perhaps due to the principal absence of two of the extrinsic peptides from photosystem II.
Sex Pheromones in Nereids: Volatile Compounds of the Coelomic Fluid of Nereis virens
Authors: Zeeck E. , Hardege J. D. 
Published: August 2018

Abstract
Volatile compounds of the pheromone bouquet of Nereis virens have been isolated and identified from the coelomic fluid of ripe sub-heteronereids. One of the minor compounds is the sex pheromone of Platynereis dumerilii, 5-methyl-3-heptanone.
A Further Contribution to the Triterpenoid Constituents of Glycyrrhiza glabra L
Authors: Elgamal M. H. A. , Hady F. K. Abdel , Hanna A. G. , Mahran G. H. , Duddeck H. 
Published: August 2018

Abstract
Pentacyclic Triterpenoids, G lycyrrhiza glabra, 1H and 13C Chemical Shifts Five pentacyclic triterpenoids have been isolated from the minor constituents of local liquorice roots, one of them (8) has not been isolated before from liquorice root. Their struc­ tural formulae and stereochemical configuration was determined by spectroscopic methods. 13C and 1H NMR data have been compiled.
Further Studies on the Biosynthesis of Pseudoisoeugenols in Tissue Cultures of Pimpinella anisum
Authors: Reichling Jürgen , Martin Rainer 
Published: August 2018

Abstract
Tissue cultures of Pimpinella anisum and P. major were used to study the biosynthesis of pseudoisoeugenols. The putative precursors were labelled with 13C with one exception that was labelled with 14C. The incorporation of the label was controlled by 13CNMR and liquid scintil­ lation, respectively. The biosynthetic sequence found was L-phenylalanine, p-cinnamic acid, p-coumaric acid, p-hydroxycoum aric alcohol, p-methoxycoumaric alcohol and anethol. The incorporation rates ranged from 0.5% to 25%.
Defence Reactions in Rhizobium-Legume Symbiosis: Phytoalexin Concentration in Vicia faba Nodules is Affected by the Host Plant Genotype
Authors: Wolff Andreas B. , Werner Dietrich 
Published: August 2018

Abstract
In the Vicia faba-Rhizobium leguminosarum symbiosis defence reactions are established by a variable phytoalexin concentration in the nodules. No differences were observed between effective (fix+) and ineffective (fix- ) nodules. In nodules of field grown plants the average phytoalexin concentration was about 3 times higher than that from sterile pot-cultured plants infected with different Rhizobium leguminosarum strains. A great variability of phytoalexin accumulation in nodules of single plants was observed. In field grown plants about 60% of the nodules of each plant had very low levels (< 50 µg wyerone g nodule fresh weight-1) the other 40% had levels between 100 and 600 µig w yerone-g nodule fresh weight-1 indicating different defence reactions in the nodules distributed over the root system of one plant. Phytoalexin accumulation was more affected by the cultivar of the host plant than by the infecting Rhizobium strain. Two inbred lines had the lowest concentration in nodules
3 ß-Hydroxysteroid Oxidoreductase in Suspension Cultures of Digitalis lanata EH RH
Authors: Warneck Hildegard Maria , Seitz Hanns Ulrich 
Published: August 2018

Abstract
A 3 β-hydroxysteroid oxidoreductase was isolated and characterized in the microsomes of Digitalis lanata cell cultures. The enzyme catalyzes the conversion of 5α-pregnane-3,20-dione to 5a-pregnan-3 β-ol-20-one and requires NAD(P)H2. The enzyme was found to have a pH optimum of 80. The reaction had an optimum incubation temperature of 25 °C with linear reduction for the first 4 h, reaching maximum enzyme activity after 7 h. Substrate kinetics for 5a-pregnane-3,20-dione and NADPH2 resulted in apparent Km-values of 18.5-20 (µM for 5a-pregnane-3,20-dione and 50-120 µM for the co-substrate NADPH2. In order to localize 3β-hydroxysteroid oxidoreductase differential centrifugation as well as linear sucrose density gradient centrifugation were performed. The results obtained lead to the conclusion that 3β-hydroxysteroid oxidoreductase is not associated with a single cell compartment, but consists of a major soluble part and a markedly smaller part of endoplasmic reticulum-associated activity
Thermal Behaviour of Lymphocyte Membrane: ESR Investigation
Authors: Mazzuca S. , Sportelli L. 
Published: August 2018

Abstract
The order parameter, S, of the plasma membrane of in toto human peripheral blood lym­ phocytes was obtained by electron spin resonance spectroscopy in the temperature range 25-41°C. This membrane is completely in the liquid crystalline state above 31 °C. In presence of the antigen ETB from Staphylococcus aureus at the concentration of 4 μ/3 × 107 cells an overall decrease of the order parameter for this membrane is observed.
The decrease of 5 is followed by an upwards shift at about 35 °C of the temperature of the liquid crystalline state.
X-Ray Structure Analysis of a Cyanoacrylate Inhibitor of Photosystem II Electron Transport
Authors: McFadden Helen G. , Craig Donald C. , Huppatz John L. , Phillips John N. 
Published: August 2018

Abstract
X-ray crystallographic data for the highly potent cyanoacrylate photosynthetic electron transport inhibitor, (Z)-ethoxyethyl 3-(4-chlorobenzylamino)-2-cyano-4-methylpent-2-enoate, are presented. This compound has a particularly high affinity for the photosystem II (PS II) herbicide receptor with a p I50 value of 9.5 (in the Hill reaction under uncoupled condi­tions with a chlorophyll concentration of 0.1 μg/ml). Data regarding the structure of small li­gands, such as this potent cyanoacrylate, which bind to the site with high affinity may be used to provide the basis for modelling studies of PS II/herbicide complexes. The X-ray data presented confirm the Z-stereochemistry of active cyanoacrylates and demonstrate the pres­ence of a planar core stabilized by an intramolecular hydrogen bond between the ester car­bonyl oxygen and a benzylamino hydrogen atom. In order to assess the importance of the benzylamino -NH -group in this type of cyanoacrylate, analogues containing a methylene group in its place were synthesized and found to be 100-and 1000-fold less active as Hill inhibitors.
X-Ray Studies on Phospholipid Bilayers. X. Interactions with Chlortetracycline Hydrochloride
Authors: Suwalsky M. , Neira F. 
Published: August 2018

Abstract
This study deals with the structural perturbations that the antibiotic chlortetracycline hy­drochloride (CTC) can produce on phospholipid bilayers. Two multibilayer systems, one built-up of dimyristoylphosphatidylethanolamine (DMPE) and the other of dimyristoylphos-phatidylcholine (DMPC) were allowed to interact with different concentrations of CTC in the absence and presence of water. The study was carried out by X-ray diffraction methods and all experiments were done below the phospholipid main transition temperatures. The results showed that CTC produced significant perturbations on DMPC even in the absence of water, whereas they were much milder in DMPE .
Safeners as Corn Seedling Protectants against Acetolactate Synthase Inhibitors
Authors: Milhomme Henri , Roux Christophe , Bastide Jean 
Published: August 2018

Zea mays L., cv. Potro, shoots had a higher level of resistance to imazaquin (IQ) and metsulfuron methyl (M SM ) than roots. Shoot lengths were increased by pretreating the seeds with commercial 1,8 -naphthalic anhydride (N A ) at 1% (w/w) or oxabetrinil at 0.2% (w/w). The growth of shoots of safened seeds was unaffected by 400 nM IQ and by 40 nM MSM. The in vivo activity of acetolactate synthase (ALS) extracted from corn shoots and roots was not affected by treatments with IQ or MSM, but pretreatment of seeds with NA or oxabetrinil, prior to germination, caused an increase in the level of extractable ALS from shoots. ALS activity from roots and shoots of NA-pretreated seedlings was increased to a large degree (> 40% ) when the seedlings were germinated on 40 nM MSM, whereas ALS activities from oxabetrinil-pretreated seedlings were enhanced to a lesser degree (≈20%). ALS from unsafened seedlings was inhibited 21% by 400 nM IQ and 70% by 40 nM MSM in vitro, but ALS from roots of seedlings germinated on 400 nM IQ was not inhibited by 400 nM IQ in
vitro.
Replikation ColE 1-verwandter Plasmide bei erhöhter Wachstumstemperatur in Abhängigkeit von der Rom-Funktion / Replication of ColE 1-Related Plasmids at Increased Growth Temperature in Dependence on the Rom Function
Authors: Riethdorf Sabine , Ulrich Andreas , Hecker Michael 
Published: August 2018

The content of ColE 1-related plasmids increased about 4-6-fold after a temperature-shift from 30 to 42 °C (45 °C) if the rom-region of the plasmids was deleted.
The copy number of rom+-plasmids did not change after the temperature shift. All rom¯-plasmids tested in this study showed this plasmid amplification. The Rom-protein is capable of inhibiting plasmid replication by stabilization the initial reversible stage of the association of RNAI with the primer precursor RNAII.
We suggest that the temperature-dependent enhancement of the copy number of rom¯-plasmids is due to a destabilization of this initial phase of the RNAI-preprimer interaction at high temperatures which is suppressed by the Rom-protein in cells with rom+-plasmids.
Studies on Uroporphyrinogen Biosynthesis in Pig Liver
Authors: Fumagalli Silvia A. , Kotier Monica L. , Rossetti María V. , del C. Batlle Alcira M. 
Published: August 2018

Porphobilinogen-deaminase (PBG-D) and PBG-D-isomerase complex (PBG-D-I) from pig liver were isolated and partially purified. Uroporphyrinogen I and III formation was found to be linear with time and protein concentration. Optimal pH was about 7.4 and 7.6-7.8 for PBG-D and PBG-D-I complex, respectively.
Some properties of the isolated enzymes were studied. Molecular mass determination gave a value of 40,000 Da for PBG-D and 50,000 Da for the complex. Both enzymes exhibited classical Michaelis-Menten kinetics. Km and Fmax parameters were estimated. The effect of several divalent cations, ammonia and thiol reagents was also investigated. The differential action of some of these chemicals on PBG-D and PBG-D-I system would suggest that PBG-D and isomerase may not be only physically adjacent but actually associated.
Photophysical and Photochemical Properties of 2,3-Dihydro-4(l H)- quinolinones. Part II. Rates and Mechanism of Primary Processes
Authors: Bakalova Sn. , Biczók L. , Bérces T. 
Published: August 2018

Abstract
Fluorescence quantum yields, singlet lifetimes and triplet yields for 2-methyl-2,3-dihydro-4(1 H)-quinolinone and N -m ethyl-2,3-dihydro-4(1 H)-quinolinone were determined as a function of temperature. In non-polar solvents, an efficient non-radiative process identified as an indirect singlet →triplet transition occurring through S2(n,π*) was found to depopulate the lowest S1(π,π*) state. In polar solvents, direct singlet → triplet intersystem crossing appears to dominate.
Photochemical dehydrogenation produced the corresponding 4(1 H)-quinolinone with a yield of few times 10-2. This was shown to be the only traceable reaction route.