Band 33, Heft 5-6

The solution conformations of 3-deazaadenosine, 3-deaza-8-azaadenosine, and benzimidazole-1-β- ᴅ-riboside have been determined by nuclear magnetic resonance methods in aqueous and ammonia solutions. The two-state S ⇄ N model of Altona and Sundaralingam is used to analyse the ribose moiety. In order to characterize the orientation of the base relative to the ribose, longitudinal proton relaxation time and nuclear Overhauser enhancement measurements have been carried out. It is shown that 3-deazaadenosine and benzimidazole-1-β-ᴅ-riboside exist preferentially in the S- syn-g + /t (70%) and the N-anti-g + /t (30%) conformation families. In the case of 3-deaza-8-aza- adenosine, some destabilization of the g + rotamer occurs. In this case, the pulsed methods seem to indicate a preference of the base for the anti range.

Stability and regenerability of the absorption spectrum of CTAB solubilized rhodopsin at an air-water interface is studied. The spectral properties of rhodopsin films in the dark are stable more than 150 minutes. When rhodopsin is bleached (40 - 50%) and maintained in highly com­ pressed films recovery of the spectrum is observed. The recovery is 57% to 100% of the pigment present before irradiation. At low surface pressure or if the films are expanded after irradiation there is no observable recovery.

The interaction of Cu (II) with the protein pepsin has been investigated by means of electron spin resonance (ESR) and optical spectroscopy. Depending on the molar ratio of Cu(II) and pepsin in aqueous solution two different complexes are formed. A third complex can be detected after a reaction time of several days, attributed to a complex with a conformationally changed pepsin. The presence of inhibitors 1,2-epoxy-3-phenoxypropane (EPP) or diazoacetyl-ethylester (DAE) seems to hinder the conformational change. The structure of the three complexes is discussed.

I report on the preparation of (9-β-ᴅ-ribofuranosyl)-s-triazolo-[1,2a]-purine-6-one (2) by cycli- zation of N-1-amino guanosine (1) with formamide. The tricyclic nucleoside analogue was charac­terized by NMR-spectroscopy ( 1 H-NMR; 13 C-NMR). The utility of 2 for the introduction of “cross­links” in double stranded nucleic acids is discussed.

The switch from embryonic to adult hemoglobin (Hb) has been studied in vivo by a correlated cytological and electrophoretic analysis of circulating red blood cells from early, purely embryonic-Hb stages to purely adult-Hb stages including the adult chicken. It has been discovered, by using an acid buffer treatment that selectively elutes adult but not embryonic Hb from intact red blood cells, that embryonic and adult Hbs occur together in single cells, and that the switch occurs simultaneously in all cells. These results together with knowledge of the chick erythroid cell dynamics and ontogenetic titers indicate that the initiation of adult Hb synthesis occurs in the circulation in cells previously committed only to embryonic Hb synthesis.

From the alcohol fraction of the epicuticular leaf wax of Hoya australis R. Br. ex Traill, a new triterpenol was isolated which, according to mass spectral and NMR data, is assumed to be A-seco-A-nor-⊿12-oleanenol.

The use of Eluchrom (Camag, Berlin) for quantitative isolation of liehen substances separated by thin layer chromatography is described. For this method only small quantities of a lichen thallus are needed (less than 0.5 g) to yield sufficient amounts of pure compounds submittable to chemical and spectroscopical identification. In the case of Nephroma cellulosum 0.15 g of the lichen thallus proved to be sufficient to identify 3 main compounds of lichen substances. Microhydrolysis, EI-masspectroscopy, FD-masspectroscopy and UV/VIS-spectroscopy of the isolated compounds confirm­ ed the presence of perlatolic acid, stenosporic acid, glomelliferic acid and zeorin.

The content of trace elements in several organs of rats under the influence of D-penicillamine (D-PA) was investigated by the neutronactivation-analysis. It could be shown an diminution of Cu, and Co under D-PA-treatment, the content of Fe, Mn, Rb and Zn was not influenced. The investigat­ ed organs didn’t show any submicroscopic alterations under D-PA. On isolated collagen fibrils of tail tendon was seen a significantly diminuition of E-moduls. In accordance with Siegel the principal effect of D-PA is thought to block the synthesis of functional groups from Schiff-base crosslink precursors but not to inhibit lysyloxidase by loss of Cu-ions of connective tissue. The thermostability of D-PA influenced fibrils is changed in stretched state only and will be due to the lack of crosslink Schiff-bases; where as the shrinking point of not stretched fibrils shows only aging dependent changes.

Messenger ribonucleoprotein particles were isolated from the polysomes of logarithmically growing plant cell cultures, pulse-labeled with [ 3 H] adenosine for 30 min. More than 80% of the labeled RNP was present in particles sedimenting between 80 S and 30 S on sucrose density gradients, but was not associated with ribosomal subunits. The size distribution differs from those reported for polysomal mRNP particles to date. After fixation with glutaraldehyde the labeled RNP particles had a buoyant density of 1.38 g/cm 3 in CsCl gradients. Radioactively labeled RNA extracted from the RNP particles showed a heterodisperse size distribution and contained poly (A) stretches as determined by affinity chromatography and ribonuclease digestion experiments.

Uptake of benzoic and salicylic acid by soybean cell suspension cultures is diffusion-mediated and exclusively leads to glucose-esters. - Veratric acid is para-demethylated to vanillic acid which is conjugated to a monoglucoside. - Nitrobenzoic acids are scarcely taken up by cell cultures with glucose-esters as sole products. - Ring-labelled derivatives of vanillylalcohol and creosol are mainly polymerized to insoluble structures, ring cleavage reactions could not be observed.

Cell suspension cultures of some 12 plants were investigated for anthranilic acid metabolism. Rapid uptake of substrate is accompanied by partial excretion of anthranilic acid-N-glucoside and followed by predominant conversion into tryptophan. Ring cleavage reactions of anthranilate could not be observed but peroxidatic polymerisation occurred to a high percentage. Anthranilic acid-N-glucoside is not permanently stored by the cell cultures.

Phytotron grown plants of Glycine max var. Caloria infected with Rhizobium japonicum 61-A-101 under controlled conditions as 14 d old seedlings develop a sharp maximum of nitrogenase activity of 13 ± 3 nmol C 2 H 4 · h -1 · mg nodule fresh weight -1 19 d after infection, followed by a long period of reduced activity (3 -5 nmol) between 30 and 45 days after infection. A higher maximum activity (18 nmol C 2 H 4 · h -1 · mg nodule -1 , lasting 7 days was found in Glycine max var. Mandarin, with a similar peroid of low activity (3 - 4 nmol) following, between 35 and 50 d after infection. Nitrogenase activity in the varieties infected with Rhizobium japonicum strain 3I1 b 85 is very similar. In both varieties, the leghaemoglobin continues to increase (3 fold) after the maximum nitrogenase activity is reached and starts to decline only after 35 to 40 d. Specific activities of the three enzymes aspartate aminotransferase (E.C.2.6.1.1.), glutamate dehydrogenase (E.C.1.4.1.2.) and alanine aminotransferase (E.C.2.6.1.2.) in the plant cell cyto­plasm are changing very similarly to nitrogenase activity in the bacteroids, whereas the specific activities of the three enzymes in the bacteroids decrease only very slightly between 19 and 45 d. For these 3 enzymes the specific activity in the bacteroids during the phase of maximum nitrogenase activity is only 20 - 40% of the specific activity in the cytoplasm. A constant low activity (0.350 units) of glutamine synthetase (E.C.6.3.1.2.) is found in bacteroids from 19 to 45 d old nodules, whereas the specific activity in the plant cytoplasm increases from about 1.2 units at 19 d to more than 6 units at 45 d. The specific activity of GOGAT (E.C.1.4.13.) in bacteroids is 2 - 3 times higher than in the plant cell cytoplasm and increases slightly. Alanine dehydrogenase (E.C.1.4.1.1.) and 3-hydroxybutyrate dehydrogenase (E.C.1.1.1.30.) activities in bacteroids increase between 19 and 35 d after infection by a factor of 2 - 3. In 35 - 45 d old nodules, the specific activity of aianine-dh in bacteroids of the same Rhizobium japonicum strain (61-A-101) from plant var. Caloria is significantly smaller than in bacteroids from plant var. Mandarin, whereas for 3-hydroxybutyrate-dh the activity in bacteroids from var. Caloria is enhanced compared to bacteroids from var. Mandarin.

Mixed monolayers of pheophytin a and α-ʟ-dimyristoyl lecithin (DML) are investigated on the water surface. The studies gain their special value from the simultaneous measurement of surface pressure and fluorescence intensity as a function of the covered area per molecule. A phase separation in the liquid state of the monolayer is established. Phase 1 exists almost exclusively of pheophytin molecules. Phase 2 exists essentially of DML domains solubilizing pheo­phytin in a concentration of 15 mol%. During the DML main transition the pheophytin solubility decreases to about 2 mol%, the excess pheophytin being precipitated within the surface layer. During the pheophytin main transition an ordered structure below the surface layer is formed. A stabilizing interaction between the pheophytin domains and their environment is observed and discussed. A sharp fluorescence change at a pressure below 0.5 dyn/cm indicates another phase transition. It very probably involves an unwrapping of pheophytin from water molecules.

A light-driven galvanic cell was constructed making use of the photosynthetic activity of isolated chloroplasts. Artificial mediators managed the transfer of electrons from the endogenous electron carriers to the platinum electrodes in each of the joined half-cells. In one the mediators were reduced by electrons originating from water. In the other the mediators were oxidized by photosystem I in the presence of an autoxidizable electron acceptor. The redox potential in the single half-cells has been studied as a function of the lipophilicity of the mediators and their concentration. Further­ more different autoxidizable acceptors and different treatments of the chloroplasts were investigated. The combined half-cells were separated by an ultrafiltration membrane. Upon illumination the system gave rise to an open circuit potential of up to 220 mV. This battery was charged with rates as high as photosynthetic electron transport rates. The results are discussed with respect to the arrangement of the cell and the properties of the components for high effectiveness and maximal potential differences.

The induction phenomenon of prompt fluorescence of the photosynthetic system in green plants reflects the adaptation of the electron transport system from a dark adapted state to a steady state under light condition. The appearance of the P-peak in the prompt fluorescence induction curve is explained by the decay of the electrochemical gradient across the thylakoid membrane in the dark. The decay of the electrochemical gradient in the dark is calculated using measured fluorescence induction curves with different times of dark adaptation. The influence of photophosphorylation inhibitors is discussed and the threshold effect of ATP-formation depending on the electrochemical gradient is explained by the coupling of the ATP-formation with the electron transport in the thylakoid membrane.

Pheophytins esterified with phytol and tetrahydrogeranylgeraniol are isolated from etiolated oat seedlings after short (1 min) exposure to light and a subsequent dark period of 15 to 20 min. After saponification of the pheophytins, a mixture of the alcohols was isolated. The structure of tetra­ hydrogeranylgeraniol was established as 3,7,11,15-tetramethyl-⊿ 2,14 hexadecadiene-1-ol (3a). The implications for chlorophyll biosynthesis are discussed.

An attempt to characterize the mechanism of inhibition of photosynthetic electron transport in isolated pea chloroplasts by the herbicide 4,6-dinitro-o-cresol (DNOC) by a comparison with the effects of 3-(3,4-dichlorophenyl)-1.1-dimethylurea (DCMU) revealed the following: 1.The percent inhibition of oxygen evolution by a given herbicide concentration is the same at various light intensities except at very low intensities where the percent inhibition becomes larger. The same results are obtained with the herbicide DCMU. 2.The concentration of DCMU causing 50% inhibition of oxygen evolution decreases with de­creasing chloroplast (and thus of chlorophyll) concentration. With DNOC, the relative decrease is much less than with DCMU. At the inhibited molecule, there appears to be a cooperative binding of DCMU with two binding sites and a noncooperative binding of DNOC with only one binding site. 3.The chlorophyll a fluorescence induction is influenced by DNOC in the same characteristic way as it is by DCMU: both herbicides cause a faster rise in fluorescence yield than in control chloroplasts, although a higher concentration of the former is required for the same effect. 4.The chlorophyll fluorescence emission spectra at 77 C K show a slight decrease in the bands at 685 and 735 nm, and no or only a very slight decrease at 695 nm upon addition of high con­centrations of either DCMU or DNOC before the onset of illumination. 5.The degree of polarization of chlorophyll a fluorescence is lower after addition of DCMU or DNOC upon excitation by 460 or 660 nm light. It is concluded that, although the chemical structure of DNOC is completely different from that of DCMU, its site and mechanism of inhibition is similar to that of DCMU. Both herbicides inhibit electron transport between the primary electron acceptor of photosystem II and the plastoquinone pool. This causes a closing of the reaction centers of photosystem II. However, the interaction with the inhibited molecule is different for the two herbicides.

The solubilized coupling factor (F 1 ) of Rps. sphaeroides chromatophores was allowed to react with fiuorescamine which led to a fluorescence labelled F 1 . After reconstitution with the depleted membranes the fluorescence-labelled F 1 was shown to restore photophosphorylation in continuous light in a similar way to the non-labelled F 1 . In parallel, a decrease of the fluorescence emission of the labelled and reconstituted coupling factor was observed. The solubilized and labelled F 1 showed also a fluorescence decrease as the polarity of the medium was increased. In single turnover flashes the fluorescence change was found to be inhibited by an uncoupling agent such as FCCP. The kinetics of the change were sensitive to phosphorylating agents and to an “energy transfer inhibitor” such as venturicidin. It is suggested that the observed fluorescence changes reflect conformational changes of the ATPase enzyme complex.

Freeze fracture technique ascertains that sarcoplasmic reticulum vesicles fuse during anisodiametric dehydration which leads to the formation of sheetlike structure of a mean extension of 5000 Å . Modification of the membrane lipids by phospholipase A 2 digestion or the incorporation of deoxycholate facilitates the coalescence of the vesicles, while it is completely prevented by lipid removal. Membrane fusion during anisodiametric dehydration is considered as resulting from the close contact of highly curved edges from which the membrane proteins have been excluded.

When [ 3 H]ecdysone is injected in intermolt crayfishes, about 60 - 70% of the total radioactivity are excreted within one hour as the unchanged hormone, but nearly no [ 3 H]ecdysterone is ex­creted. The remaining [ 3 H]ecdysone in the body is effectively converted to [ 3 H] ecdysterone. In addition polar and apolar metabolites of both molting hormones can be extracted in an organ specific pattern. On the basis of radioactivity per g fresh weight hypodermis and male gonads and to a lesser extent hindgut and midgut gland contain most of the injected radioactivity. It can be demonstrated from in vitro experiments using the charcoal adsorption test and equilibrium dialysis that the cytosol of target tissues is able to bind both hormones with the highest capacity for hypo­dermis and male gonads. Both molting hormones do not appear to be bound to carrier proteins in the hemolymph.

High-molecular weight polyaldehydes, which can be obtained by periodate oxidation of glycosubstances, especially polysaccharides, do precipitate in a specific way by Schiff base formation, when diffusing in agar gel against high-molecular weight, naturally occurring polyamines.

The identification of Ca 2+ by X-ray microanalysis in statoliths could be masked by Ba 2+ . Using Ba 2+ and Ca 2+ containing standards prepared from algal cell walls and cellulose acetate films it is shown that there is no inter­ference of Ba 2+ with Ca 2+ . Hence Ba 2+ is the main cationic constituent in the statoliths of Chara rhizoids.

2′-Chloro-1-hydroxy-2-naphthanilide-4′-isothiocyanate (4) has been synthesized as the structural analogue of yomesan (1) and was found to be active against experimental dwarf tapeworm Hymenolepis nana infection in rats at an oral dose of 7.5 mg/kg.

The crystalline and amorphous constituents of Letharia vulpina collected at Flensjoen, Sor-Trendelag, Norway, have been identified as atranorin, vulpinic-, pulvinic-, usnic-, benzoic- and hydroxyfatty acids. Vulpinic acid thallate(I) and vulpinic acid isopropylether have been prepared as new derivatives. The identity of the compounds was established by consideration of elemental analyses, infrared, mass and nuclear magnetic resonance spectra, and thin layer chro­matography.

In the barnacle Balanus balanus L. the light reactions (increased activity) and shadow reactions (decreased activi­ty) depend on adaptation: As reaction to an increase of stimulus duration the barnacles show an increase of response intensity. By contrast, this paper reports on an increase of response intensity as a result of decreased stimulus dura­tion. To understand this contradictory behaviour, two adap­tive systems are assumed to be existent.

A new torque/thrust meter is described. Torque, thrust, wing-beat frequency and spike activity in direct flight muscles are recorded simultaneously during optomotor responses of the fly Musca domestica.