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Université de Neuchâtel

Broadly tunable mid-infrared quantum cascade lasers for spectroscopic applications

Maulini, Richard ; Faist, Jérôme (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2006 ; 1895.

Quantum cascade lasers are unipolar semiconductor lasers based on intersubband transitions in heterostructures. These lasers, which have demonstrated continuous wave operation at room temperature in the mid-infrared spectral range, are well suited for the realization of compact, ultra-sensitive, trace-gas sensors based on absorption spectroscopy. Up to now, only distributed feedback (DFB)...

Université de Neuchâtel

Adenosine 5'-Phosphosulfate Sulfotransferase and Adenosine 5'-Phosphosulfate Reductase Are Identical Enzymes

Suter, Marianne ; von Ballmoos, Peter ; Kopriva, Stanislav ; Op den Camp, Roel ; Schaller, Johann ; Kuhlemeier, Cris ; Schürmann, Peter ; Brunold, Christian

In: The Journal of Biological Chemistry, 2000, vol. 275, no. 2, p. 930-936

Adenosine 5'-phosphosulfate (APS) sulfotransferase and APS reductase have been described as key enzymes of assimilatory sulfate reduction of plants catalyzing the reduction of APS to bound and free sulfite, respectively. APS sulfotransferase was purified to homogeneity from Lemna minor and compared with APS reductase previously obtained by functional complementation of a mutant strain of...

Université de Neuchâtel

Activation of the Potato Tuber ADP-glucose Pyrophosphorylase by Thioredoxin

Ballicora, Miguel A. ; Frueauf, Jeremiah B. ; Fu, Yingbin ; Schürmann, Peter ; Preiss, Jack

In: The Journal of Biological Chemistry, 2000, vol. 275, no. 2, p. 1315-1320

The potato tuber (Solanum tuberosum L.) ADP-glucose pyrophosphorylase (ADP-GlcPPase) catalyzes the first committed step in starch biosynthesis. The main type of regulation of this enzyme is allosteric, and its activity is controlled by the ratio of activator, 3-phosphoglycerate to inhibitor, Pi. It was reported (Fu, Y., Ballicora, M. A., Leykam, J. F., and Preiss, J. (1998)...

Université de Neuchâtel

Kinetics and Thioredoxin Specificity of Thiol Modulation of the Chloroplast H+-ATPase

Schwarz, Oliver ; Schürmann, Peter ; Strotmann, Heinrich

In: The Journal of Biological Chemistry, 1997, vol. 272, no. 27, p. 16924-16927

The kinetics of thiol modulation of the chloroplast H+-ATPase (CF0CF1) in membrana were analyzed by employing thioredoxins that were kept reduced by 0.1 mM dithiothreitol. The kinetics of thiol modulation depend on the extent of the proton gradient. The process is an exponential function of the thioredoxin concentration and reaction time and can be...

Université de Neuchâtel

Crystal structures of two functionally different thioredoxins in spinach chloroplasts

Capitani, Guido ; Markovi-Housley, Zora ; del Val, Gregorio ; Morris, May ; Jansonius, Johan N. ; Schürmann, Peter

In: Journal of Molecular Biology, 2000, vol. 302, no. 1, p. 135-154

Thioredoxins are small ubiquitous proteins which act as general protein disulfide reductases in living cells. Chloroplasts contain two distinct thioredoxins (•f and m) with different phylogenetic origin. Both act as enzyme regulatory proteins but have different specificities towards target enzymes. Thioredoxin f (Trx f), which shares only low sequence identity with thioredoxin m...

Université de Neuchâtel

A complete ferredoxin/thioredoxin system regulates fundamental processes in amyloplasts

Balmer, Yves ; Vensel, William H. ; Cai, Nick ; Manieri, Wanda ; Schürmann, Peter ; Hurkman, William J. ; Buchanan, Bob B.

In: Proceedings of the National Academy of Sciences of the United States of America (PNAS), 2006, vol. 103, no. 8, p. 2988-2993

A growing number of processes throughout biology are regulated by redox via thiol–disulfide exchange. This mechanism is particularly widespread in plants, where almost 200 proteins have been linked to thioredoxin (Trx), a widely distributed small regulatory disulfide protein. The current study extends regulation by Trx to amyloplasts, organelles prevalent in heterotrophic plant tissues that,...

Université de Neuchâtel

α-Glucan, water dikinase (GWD) : A plastidic enzyme with redox-regulated and coordinated catalytic activity and binding affinity

Mikkelsen, René ; Mutenda, Kudzai E. ; Mant, Alexandra ; Schürmann, Peter ; Blennow, Andreas

In: Proceedings of the National Academy of Sciences of the United States of America (PNAS), 2005, vol. 102, no. 5, p. 1785-1790

The recently discovered potato tuber (Solanum tuberosum) -glucan, water dikinase (GWD) (formerly known as R1) catalyzes the phosphorylation of starch by a dikinase-type reaction mechanism in which the β-phosphate of ATP is transferred to either the C-6 or the C-3 position of the glucosyl residue of starch. In the present study, we found that the GWD enzyme is inactive in the oxidized...

Université de Neuchâtel

Thioredoxin links redox to the regulation of fundamental processes of plant mitochondria

Balmer, Yves ; Vensel, William H. ; Tanaka, Charlene K. ; Hurkman, William J. ; Gelhaye, Eric ; Rouhier, Nicolas ; Jacquot, Jean-Pierre ; Manieri, Wanda ; Droux, Michel ; Schürmann, Peter ; Buchanan, Bob B.

In: Proceedings of the National Academy of Sciences of the United States of America (PNAS), 2004, vol. 101, no. 8, p. 2642-2647

Mitochondria contain thioredoxin (Trx), a regulatory disulfide protein, and an associated flavoenzyme, NADP/Trx reductase, which provide a link to NADPH in the organelle. Unlike animal and yeast counterparts, the function of Trx in plant mitochondria is largely unknown. Accordingly, we have applied recently devised proteomic approaches to identify soluble Trx-linked proteins in mitochondria...

Université de Neuchâtel

Proteomics gives insight into the regulatory function of chloroplast thioredoxins

Balmer, Yves ; Koller, Antonius ; del Val, Gregorio ; Manieri, Wanda ; Schürmann, Peter ; Buchanan, Bob B.

In: Proceedings of the National Academy of Sciences of the United States of America (PNAS), 2003, vol. 100, no. 1, p. 370-375

Thioredoxins are small multifunctional redox active proteins widely if not universally distributed among living organisms. In chloroplasts, two types of thioredoxins (f and m) coexist and play central roles in regulating enzyme activity. Reduction of thioredoxins in chloroplasts is catalyzed by an iron-sulfur disulfide enzyme, ferredoxin-thioredoxin reductase, that receives...

Université de Neuchâtel

The plant-specific function of 2-Cys peroxiredoxin-mediated detoxification of peroxides in the redox-hierarchy of photosynthetic electron flux

König, Janine ; Baier, Margarete ; Horling, Frank ; Kahmann, Uwe ; Harris, Gary ; Schürmann, Peter ; Dietz, Karl-Josef

In: Proceedings of the National Academy of Sciences of the United States of America, 2002, vol. 99, no. 8, p. 5738-5743

The 2-cysteine peroxiredoxins (2-Cys Prx) constitute an ancient family of peroxide detoxifying enzymes and have acquired a plant-specific function in the oxygenic environment of the chloroplast. Immunocytochemical analysis and work with isolated intact chloroplasts revealed a reversible binding of the oligomeric form of 2-Cys Prx to the thylakoid membrane. The oligomeric form of the enzyme was...