Olivier Maury

Cationic Two-Photon Lanthanide Bioprobes Able to Accumulate in Live Cells

An original cationic water-soluble cyclen-based Eu(III) complex [EuL(1)](+) featuring a chromophore-functionalized antenna to increase the two-photon (2P) absorption properties was synthesized. The photophysical properties were thoroughly studied in various solvents and rationalized with the help of theoretical calculations. The complex exhibits an optimized 2P absorption cross section. Finally, 2P microscopy imaging experiments on living T24 human cancer cells highlighted the spontaneous internalization and the biological stability of this 2P bioprobe in vitro. Macrocyclic-based antennas open new perspectives for future optimization of the photophysical properties and allows envisaging the design of Eu, Tb, Yb, and Sm bioprobes. This result also opens the way for the design of functional two-photon Ln complexes able to monitor intracellular physicochemical parameters.

The multicatalytic compartment of propionyl-CoA synthase sequesters a toxic metabolite

Cells must cope with toxic or reactive intermediates formed during metabolism. One coping strategy is to sequester reactions that produce such intermediates within specialized compartments or tunnels connecting different active sites. Here, we show that propionyl-CoA synthase (PCS), an ∼u2009400-kDa homodimer, three-domain fusion protein and the key enzyme of the 3-hydroxypropionate bi-cycle for CO2 fixation, sequesters its reactive intermediate acrylyl-CoA. Structural analysis showed that PCS forms a multicatalytic reaction chamber. Kinetic analysis suggested that access to the reaction chamber and catalysis are synchronized by interdomain communication. The reaction chamber of PCS features three active sites and has a volume of only 33u2009nm3. As one of the smallest multireaction chambers described in biology, PCS may inspire the engineering of a new class of dynamically regulated nanoreactors.Structural and biochemical analysis of propionyl-CoA synthase reveals that it forms a reaction chamber containing three active sites, which sequesters the reactive intermediate acrylyl-CoA during the conversion of 3-hydroxypropionate to propionyl-CoA.

Correction to “Terbium(iii) Luminescent Complexes as Millisecond-Scale Viscosity Probes for Lifetime Imaging”

T influence of dissolved oxygen in the photophysical measurements presented in this Communication was underestimated. Following a recent publication by Williams, Parker, and co-workers, luminescence measurements of compound [TbL] were carried out in air-equilibrated and degassed methanol and glycerol solutions. In methanol, very strong enhancement of luminescence properties was observed as oxygen concentration decreased; specifically, the luminescence lifetime increased significantly from 0.22 ms in airequilibrated medium to 1.26 ms in degassed methanol. In contrast, a modest increase was observed in glycerol upon degassing, from 0.86 to 1.00 ms. The comparable lifetimes measured for [TbL] in degassed methanol and degassed glycerol suggest that viscosity does not play the major role. On the other hand, in air-equilibrated solvents the difference in luminescence lifetimes can be correlated in a first approximation to the large difference of oxygen solubility, varying from 4.15 × 10−4 in methanol to 4.8 × 10−6−5.5 × 10−6 in glycerol, expressed as mole fractions at 298 K and 101.3 kPa. While the lifetime measurements performed in various airequilibrated methanol−glycerol mixtures are valid (Figure 2a), their interpretation as a function of the medium viscosity (Figure 2b) is incorrect. Instead, the results should be read as a function of oxygen concentration, which decreases as glycerol content increases.