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1.
Summary The soil yeast Trichosporon cutaneum was grown in continuous culture on phenol, acetate or glucose as sole carbon source. The activities of enzymes participating in the tricarboxylic acid cycle, glyoxylate cycle, 3-oxoadipate pathway, pentose phosphate pathway and glycolysis were determined in situ during shifts of carbon sources. Cells grown on phenol or glucose contained basal activity of the glyoxylate-cycle-specific isocitrate lyase. The derepression of the glyoxylate cycle enzymes was partly hindered in the presence of phenol but not in the presence of low levels of glucose. Phenol and glucose caused repression of isocitrate lyase. In the presence of either phenol or glucose, acetate accumulation in the medium increased. However, part of the supplied acetate was utilized simultaneously with phenol or glucose, the utilization rate of either carbon source being reduced in the presence of the other carbon source. Acetate caused repression but not inactivation of the phenol-degrading enzymes, phenol hydroxylase and catechol 1,2-dioxygenase. The simultaneous utilization of phenol and other carbon sources in continuous culture as well as the observed repression-derepression patterns of the involved enzymes reveal T. cutaneum to be an organism of interest for possible use in decontamination processes.
Offprint requests to: H. Y. Neujahr
Offprint requests to: H. Y. Neujahr 相似文献
2.
Zhao Rongrui Wang Wenze Wu Bowei Hoebeke Johan Hjalmarson Åke Fu Michael L. X. 《Molecular and cellular biochemistry》1996,163(1):185-193
The effects of anti-peptide antibodies against the second extracellular loop of human M2 muscarinic receptor on transmembrane potentials and currents in guinea pig single ventricular cells were analyzed using whole-cell patch clamp technique. These effects were compared with those of the muscarinic receptor agonists carbachol and acetylcholine. The antibodies shortened the action potential duration in a dose-dependent manner. By using a ramp or step rectangular pulse protocol, it was found that the antibodies increased the outward K+ current and decreased the inward basal I Ca significantly. The reversal potential of both carbachol-and antibody-induced extra currents were close to –80 mV, being in proximity to the calculated Ek of –90 mV. A -adrenergic receptor agonist, isoprenaline, prolonged the action potential and increased the overshoot which could be inhibited by both antibody and carbachol. Isoprenaline increased inward Ica and outward Ik simultaneously. Both antibody and carbachol could significantly reduce the isoprenaline-stimulated ICa but not the isoprenaline-stimulated Ik. The antibody- or carbachol-induced outward K+ current and the depressant effects of antibody and carbachol on isoprenaline-stimulated Ica were partially antagonized by atropine. These results suggest that the anti-M2 muscarinic receptor antibodies display a stimulatory activity similar to muscarinic receptor agonist on the receptor-mediated electrophysiological events. 相似文献
3.
Per-Ola Arvidsson Charlotte Eva Bratt Lars-Erik Andréasson Hans-Erik Åkerlund 《Photosynthesis research》1993,37(3):217-225
Photosystem II (PS II) particles isolated from spinach in the presence of 10 M CuSO4 contained 1.2 copper/300 Chl that was resistant to EDTA. When CuSO4 was not added during the isolation, PS II particles contained variable amounts of copper resistant to EDTA (0.1–1.1 copper/300 Chl). No correlation was found between copper content and oxygen evolving capacity of the PS II particles. To identify the copper binding protein, we developed a fractionation procedure which included solubilisation of PS II particles followed by precipitation with polyethylene glycol. A 22-fold purification of copper with respect to protein was achieved for a 28 kDa protein. Partial amino acid sequence of a 13 kDa fragment, obtained after V8 (endo Glu-C) protease treatment, showed identity with CP 26 over a 14 amino acid stretch. EPR measurements on the purified protein suggest oxygen and/or nitrogen as ligands for copper but tend to exclude sulfur. We conclude that the 28 kDa apoprotein of CP 26 from spinach binds one copper per molecule of CP 26. A possible function for this copper protein in the xanthophyll cycle is discussed.Abbreviations CP 26 and CP 29
chlorophyll a/b protein complex 26 and 29
- LHC II
light-harvesting chlorophyll a/b protein complex of Photosystem II
- SB14
sulfobetaine 14
A preliminary report of these results was presented at the IX Int. Congress on Photosynthesis, Nagoya, Japan, 1992. 相似文献
4.
Lars-Åke Fransson Anders Malmström Ingrid Sjöberg Thomas N. Huckerby 《Carbohydrate research》1980,80(1):131-145
Heparin, heparan sulphate, and various derivatives thereof have been oxidised with periodate at pH 3.0 and 4° and at pH 7.0 and 37°. Whereas oxidation under the latter conditions destroys all of the nonsulphated uronic acids, treatment with periodate at low pH and temperature causes selective oxidation of uronic acid residues. The reactivity of uronic acid residues depends on the nature of neighbouring 2-amino-2-deoxyglucose residues. d-Glucuronic acid residues are susceptible to oxidation when flanked by N-acetylated amino sugars, but resistant when adjacent residues are either unsubstituted or N-sulphated. L-Iduronic acid residues in their natural environment (2-deoxy-2-sulphoamino-d-glucose) are resistant to oxidation, whereas removal of N-sulphate groups renders a portion of these residues periodate-sensitive. Oxidised uronic acid residues in heparin-related glycans may be cleaved by alkali, producing a series of oligosaccharide fragments. Thus, periodate oxidation-alkaline elimination provides an additional method for the controlled degradation of heparin. 相似文献
5.
6.
Wong L Lieser SA Miyashita O Miller M Tasken K Onuchic JN Adams JA Woods VL Jennings PA 《Journal of molecular biology》2005,351(1):131-143
The C-terminal Src kinase (Csk) phosphorylates and down-regulates Src family tyrosine kinases. The Csk-binding protein (Cbp) localizes Csk close to its substrates at the plasma membrane, and increases the specific activity of the kinase. To investigate this long-range catalytic effect, the phosphorylation of Src and the conformation of Csk were investigated in the presence of a high-affinity phosphopeptide derived from Cbp. This peptide binds tightly to the SH2 domain and enhances Src recognition (lowers K(m)) by increasing the apparent phosphoryl transfer rate in the Csk active site, a phenomenon detected in rapid quench flow experiments. Previous studies demonstrated that the regulation of Csk activity is linked to conformational changes in the enzyme that can be probed with hydrogen-deuterium exchange methods. We show that the Cbp peptide impacts deuterium incorporation into its binding partner (the SH2 domain), and into the SH2-kinase linker and several sequences in the kinase domain, including the glycine-rich loop in the active site. These findings, along with computational data from normal mode analyses, suggest that the SH2 domain moves in a cantilever fashion with respect to the small lobe of the kinase domain, ordering the active site for catalysis. The binding of a small Cbp-derived peptide to the SH2 domain of Csk modifies these motions, enhancing Src recognition. 相似文献
7.
Kjetil Taskn Rigmor Solberg Ying Zhao Vidar Hansson Tore Jahnsen Michael J. Siciliano 《Genomics》1996,36(3):535
We have determined the chromosomal localization of the gene for the catalytic subunit Cα of cAMP-dependent protein kinase (locus PRKACA) to human chromosome 19 using polymerase chain reaction (PCR) and Southern blot analysis of two different somatic cell hybrid mapping panels. In addition, PCR analysis of a chromosome 19 mapping panel revealed the presence of a human Cα-specific amplification product only in cell lines containing the region 19p13.1 to 19q12. Finally, two-color fluorescencein situhybridization to metaphase chromosomes using the human Cα cDNA and human chromosome 19 inter-Alu-PCR product as probes localized the human Cα gene to chromosome region 19p13.1. 相似文献
8.
A 23 kDa protein has recently been demonstrated to participate in photosynthetic oxygen evolution by reconstitution experiments on inside-out thylakoid vesicles (Åkerlund H-E, Jansson C and Andersson B (1982) Biochim Biophys Acta 681:1–10). Here we describe the isolation of the 23 kDa protein from a spinach chloroplast extract using ion-exchange chromatography. The protein was obtained in a yield of 25% and with less than 1% of contaminating proteins. The ability of the protein to stimulate oxygen evolution in inside-out thylakoids was preserved throughout the various fractionation steps. The isolated protein was highly water soluble and appeared as a monomer. Its isoelectric point was at pH=7.3. The amino acid composition showed a high content of polar amino acids, resulting in a polarity index of 49%. The isolated protein lacked metals and other prosthetic groups. Its function as a catalytic or regulating subunit in the oxygen evolving complex is discussed. 相似文献
9.
Recent developments in the field of genetic divergence and speciation focus more on diversifying processes than on geographic
mode of speciation (i.e. allopatric versus sympatric). Some of these new theories concern speciation driven by conflicts between
the sexes. Even though it is well known that the two reproductive functions in plants can have different selective optima,
sexual selection in plants is by many assumed to be weak or non-existent. Here we outline potential sexual conflicts in plants
and discuss how selection pressures generated by such conflicts may influence genetic divergence. There is opportunity for
conflicting selection pressures between individuals, such as manipulative pollen traits that enhance male reproductive success
at the expense of the female reproductive function. Within individual plants, fitness of the male function (pollen export)
and fitness of the female function (pollen import) may be optimised by different traits, leading to conflicting selection
pressures in relation to pollen transfer. This may affect selection for floral specialisation versus floral generalisation
in animal-pollinated species. We believe that selection pressures generated by sexual conflict need to be appreciated in order
to fully understand microevolutionary processes which may lead to genetic divergence and speciation in plants. 相似文献
10.
Defective regulation of the cytosolic Ca2+ activity in parathyroid cells from patients with hyperparathyroidism 总被引:2,自引:0,他引:2
Rolf Larsson Chris Wallfelt Håkan Abrahamsson Erik Gylfe Sverker Ljunghall Jonas Rastad Patrik Rorsman Leif Wide Göran Åkerström 《Bioscience reports》1984,4(11):909-915
The parathyroid hormone (PTH) release and cytosolic Ca2+ activity were determined in normal bovine parathyroid cells and parathyroid cells obtained from patients with hyperparathyroidism (HPT). There was a sigmoid relation between the cytosolic Ca2+ activity and the extracellular calcium concentration between 0.5 and 6.0 mmol/l. The PTH release was inhibited in parallel with the rise in the cytosolic Ca2+ activity. Both the hormone release and the cytosolic Ca2+ activity were lower in cells from human adenomas and hyperplastic glands~ and in comparison with the bovine preparations these ceils had higher set points for the cytosolic Ca2+ activity and PTH release. There was a close correlation between the individual set points for the cytosolic Ca2+ activity and PTH release in a material containing both normal and pathological cells. The results indicate that the abnormal PTH release characteristic of HPT is due to a defective regulation of the cytosolic Ca2+ activity. 相似文献