6 research outputs found
Gewerkschaftlicher Organisationsaufbau und Transformation der Lohnpolitik im Prozess der deutschen Einheit die IG Metall in den neuen Bundeslaendern 1990-1993
UuStB Koeln(38)-940106688 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Wirtschaftliche Lage und soziale Differenzierung im Transformationsprozess Zwischenbilanz der sozio-oekonomischen Transformation der neuen Bundeslaender fuer die Analyse der entstehenden Interessenvermittlungsstruktur
SIGLEUuStB Koeln(38)-940106441 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Interessenverbaende im Transformationsprozess zur Repraesentations- und Steuerungsfaehigkeit des Verbaendesystems der neuen Bundeslaender
UuStB Koeln(38)-940106442 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Engineering an Artificial Flavoprotein Magnetosensor
Migratory birds use the Earth’s magnetic field as a source of navigational information. This light-dependent magnetic compass is thought to be mediated by cryptochrome proteins in the retina. Upon light activation, electron transfer between the flavin adenine dinucleotide cofactor and tryptophan residues leads to the formation of a spin-correlated radical pair, whose subsequent fate is sensitive to external magnetic fields. To learn more about the functional requirements of this complex chemical compass, we have created a family of simplified, adaptable proteins—maquettes—that contain a single tryptophan residue at different distances from a covalently bound flavin. Despite the complete absence of structural resemblance to the native cryptochrome fold or sequence, the maquettes exhibit a strong magnetic field effect that rivals those observed in the natural proteins in vitro. These novel maquette designs offer unprecedented flexibility to explore the basic requirements for magnetic sensing in a protein environment
Magnetically Sensitive Radical Photochemistry of Non-natural Flavoproteins
It
is a remarkable fact that ∼50 μT magnetic fields
can alter the rates and yields of certain free-radical reactions and
that such effects might be the basis of the light-dependent ability
of migratory birds to sense the direction of the Earth’s magnetic
field. The most likely sensory molecule at the heart of this chemical
compass is cryptochrome, a flavin-containing protein that undergoes
intramolecular, blue-light-induced electron transfer to produce magnetically
sensitive radical pairs. To learn more about the factors that control
the magnetic sensitivity of cryptochromes, we have used a set of <i>de novo</i> designed protein maquettes that self-assemble as
four-α-helical proteins incorporating a single tryptophan residue
as an electron donor placed approximately 0.6, 1.1, or 1.7 nm away
from a covalently attached riboflavin as chromophore and electron
acceptor. Using a specifically developed form of cavity ring-down
spectroscopy, we have characterized the photochemistry of these designed
flavoprotein maquettes to determine the identities and kinetics of
the transient radicals responsible for the magnetic field effects.
Given the gross structural and dynamic differences from the natural
proteins, it is remarkable that the maquettes show magnetic field
effects that are so similar to those observed for cryptochromes