L'Ecologisme en Allemagne et en France : deux modes différents de construction d'un nouvel acteur politique

SummaryThe N-terminally truncated variant of photoactive yellow protein (Δ25-PYP) undergoes a very similar photocycle as the corresponding wild-type protein (WT-PYP), although the lifetime of its light-illuminated (pB) state is much longer. This has allowed determination of the structure of both its dark- (pG) as well as its pB-state in solution by nuclear magnetic resonance (NMR) spectroscopy. The pG structure shows a well-defined fold, similar to WT-PYP and the X-ray structure of the pG state of Δ25-PYP. In the long-lived photocycle intermediate pB, the central β sheet is still intact, as well as a small part of one α helix. The remainder of pB is unfolded and highly flexible, as evidenced by results from proton-deuterium exchange and NMR relaxation studies. Thus, the partially unfolded nature of the presumed signaling state of PYP in solution, as suggested previously, has now been structurally demonstrated

Photoinduced isomerisation of cis-[M(L-S,O)2] (M = Pt II and PdII) complexes of N,N-diethyl-N′-3,4,5- trimethoxybenzoylthiourea: Key to preparation of the trans isomer

In acetonitrile solutions at room temperature, cis-[M(L-S,O)2] PtII and PdII complexes of N,N-diethyl-N′-3,4,5- trimethoxybenzoylthiourea undergo reversible photoinduced isomerisation to the corresponding trans isomer upon irradiation with visible light in the 320-570 nm range, the rate and extent of isomerisation being significantly higher for the cis-[Pd(L-S,O)2] complex compared to the PtII analogue; in the dark trans-[M(L-S,O)2] cleanly reverts back to the cis complex at a rate dependent on the solution temperature, indicating a thermally controlled reverse process. © The Royal Society of Chemistry 2005.Articl

Lack of negative charge in the E46Q mutant of photoactive yellow protein prevents partial unfolding of the blue shifted intermediate

The long-lived light-induced intermediate (pB) of the E46Q mutant (glutamic acid is replaced by glutamine at position 46) of photoactive yellow protein (PYP) has been investigated by NMR spectroscopy. The ground state of this mutant is very similar to that of wild-type PYP (WT), whereas the pB state, formed upon illumination, appears to be much more structured in E46Q than in WT. The differences are most striking in the N-terminal domain of the protein. In WT, the side-chain carboxylic group of E46 is known to donate its proton to the chromophore upon illumination. The absence of the carboxylic group near the chromophore in the E46Q mutant prohibits the formation of a negative charge at this position upon formation of pB. This prevents the partial unfolding of the mutant, as evidenced from NMR chemical shift comparison and proton/deuterium (H/D) exchange studies