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191.
Marcia R. Brochetto-Braga Suely Lopes Gomes JoséCarlos Da Costa Maia 《Archives of biochemistry and biophysics》1982,217(1):295-304
Using a combination of Chromatographic and sucrose density gradient techniques under carefully controlled conditions of pH and protease inhibitors, we demonstrate that there is only one form of adenosine 3′,5′-monophosphate-dependent protein kinase in the cytosol fraction of the Blastocladiella emersonii zoospore. If any of these conditions are omitted during extract preparation, one obtains what are apparently multiple forms of the enzyme, which are in reality artifacts due to extensive endogenous proteolytic activity. This endogenous protease is stimulated by alkaline pH and inhibited by antipain. The zoospore protein kinase is similar to type II protein kinase from mammalian cells in several aspects including Chromatographic behavior on DEAE-cellulose column, conditions for subunit dissociation and reassociation, as well as the molecular weight value of the regulatory subunit. 相似文献
192.
The gas-liquid-chromatographic retention-times and the mass-spectral features of partially methylated d-galactononitrile acetates are reported. Distinctive fragmentation of each of the mono-O-methyl derivatives allows their identification, and the results are applicable to the same substituted derivatives of the other aldohexoses. A new fragmentation-pathway, typical of the acetylated and the O-acetyl-O-methylaldononitriles, is proposed in order to justify previously unexplained fragments. This fragmentation competes with the known ones in derivatives that do not carry vicinal methoxyl groups. 相似文献
193.
Bledius (Elbidus) bicornis (Germ.) and B. (Eucerotobledius) furcatus (Oliv.) (Coleoptera: Staphylinidae) are the most important burrowing species in the emergent areas and shores in the athalassic
lake of Fuente de Piedra (Málaga, S. of Spain).
A first estimate of the importance of these organisms in this system is presented. These insects kick out sediment during
their burrowing activity, which accumulates on the surface near the burrows as tumuli which can be easily eroded. The lake
perimeter (17 km) is densely colonized (usual densities from 1700 to 2500 ind m−2). The amount of granulated material that can be potentially kicked out was 46.22 g dry wt m−2 day−1. At the same time, the material that constitutes the tumuli shows different characteristics from the compact ground below
the surface. Thus, it is relatively enriched with organic matter (6.15 g per square meter), soluble phosphate (406.5 μg m−2) and ammonium (4856 μg m−2), whereas it lacks nitrate. Results of a transect from uninhabited areas to zones of maximum population density also show
a similarity between the higher ground level of ammonium and phosphate concentrations and population density. 相似文献
194.
Cell carbon and nitrogen in D. viridis are strongly dependent on the culturing conditions. Both elements increase with increasing salinity. At 31°C cell carbon is maximum and cell nitrogen minimum. This temperature was described previously (Jiménez, C., Niell, F. X. & Fernandez, J. A. (1990). Hydrobiologia, 197, 165-72) as the optimal one for achieving the maximum oxygen evolution. These results point out a possible competence for the reducing power during carbon and nitrogen assimilation processes, and under conditions of high photosynthesis (carbon assimilation) there is a partial inhibition of nitrate reduction, making C:N ratio maximum under conditions of maximum net photosynthesis.The study of cell glycerol, nitrate, structural proteins and free amino acids indicates that all of these solutes accumulate in the cells as a result of the high salinity adaptation. 相似文献
195.
196.
The metabolism of lactate in isolated cells from early neonatal rat brain has been studied. In these circumstances, lactate was mainly oxidized to CO2, although a significant portion was incorporated into lipids (78% sterols, 4% phosphatidylcholine, 2% phosphatidylethanolamine, and 1% phosphatidylserine). The rate of lactate incorporation into CO2 and lipids was higher than those found for glucose and 3-hydroxybutyrate. Lactate strongly inhibited glucose oxidation through the pyruvate dehydrogenase-catalyzed reaction and the tricarboxylic acid cycle while scarcely affecting glucose utilization by the pentose phosphate pathway. Lipogenesis from glucose was strongly inhibited by lactate without relevant changes in the rate of glycerol phosphate synthesis. These results suggest that lactate inhibits glucose utilization at the level of the pyruvate dehydrogenase-catalyzed reaction, which may be a mechanism to spare glucose for glycerol and NADPH synthesis. The effect of 3-hydroxybutyrate inhibiting lactate utilization only at high concentrations of 3-hydroxybutyrate suggests that before ketogenesis becomes active, lactate may be the major fuel for the neonatal brain. (-)-Hydroxycitrate and aminooxyacetate markedly inhibited lipogenesis from lactate, suggesting that the transfer of lactate carbons through the mitochondrial membrane is accomplished by the translocation of both citrate and N-acetylaspartate. 相似文献
197.
Summary The oxidation of Ca–Mg lactate to Ca–Mg acetate (CMA) deicing salt was studied in pure cultures ofAcetobacter pasteurianus, Gluconobacter cerinus orG. oxydans. Gluconobacter sp., which maintained a practically self-controlled pH reaction and did not overoxidize acetate, appear to be potentially important for CMA production. 相似文献
198.
199.
Carlos Garbisu Jone M. Gil Michael J. Bazin David O. Hall Juan L. Serra 《Journal of applied phycology》1991,3(3):221-234
Cells of the non-N2-fixing cyanobacteriumPhormidium laminosum were immobilized in polyurethane (PU) foams either by absorption or by entrapment in the PU prepolymer followed by polymerisation
and by adsorption onto polyvinyl (PV) foams. Although entrapment caused toxicity problems which lead to rapid death of the
immobilized cells, they were immobilized successfully by adsorption onto PU or PV foams and maintained their photosynthetic
electron transport activities (PS I, II, I + II) for at least 7 weeks. Changes in the morphology resulting from immobilization,
as revealed by scanning electron microscopy (SEM) and low temperature-SEM, were investigated. Batch cultures and a continuous-flow
packed bed photobioreactor were used to study nitrate removal from water. The effects of light intensity and CO2 concentration on bioreactor performance were studied with respect to the nitrate uptake efficiency of the system. It was
concluded thatP. laminosum immobilized on polymer foams is of potential value for biological nitrate removal in a continuous-flow system.
author for correspondence 相似文献
200.
Manuel Rico Jorge Santoro Carlos González Marta Bruix José Luis Neira José Luis Nieto José Herranz 《Journal of biomolecular NMR》1991,1(3):283-298
Summary A method is proposed to generate initial structures in cases where the distance geometry method may fail, such as when the set of1H NMR NOE-based distance constraints is small in relation to the size of the protein. The method introduces an initial correlation between the and backbone angles (based on empirical observations) which is relaxed in later stages of the calculation. The obtained initial structures are refined by well-established methods of energy minimization and restrained molecular dynamics. The method is applied to determine the solution structure of Ribonuclease A (124 residues) from a NOE basis consisting of 467 NOE cross-correlations (97 intra-residue, 206 sequential, 23 medium-range and 141 long-range) obtained at 360 MHz. The global shape and backbone overall fold of the eight final refined structures are close to those shown by the crystal structure. A meaningful difference in the positioning of the catalytically important His119 side chain in the solution and crystal structures has been detected. 相似文献