The excited-state chemistry of phycocyanobilin: a semiempirical study.

Based on previous time-resolved absorption studies, phycocyanobilin undergoes a photoreaction from an A- into a B- and C-form, with the latter two photoproducts showing absorption spectra red-shifted from A. To identify the molecular mechanism involved in the excited-state reactions, the structural origin of the red shift in the absorption spectra is investigated. Using semiempirical AM1 calculations that include configuration interaction by pair doubles excitation configuration interaction, the absorption spectra of different conformers as well as different protonation states were calculated.

Global expression analysis of the fibroblast transcriptional response to TGFbeta.

Objectives: Transforming Growth Factor-beta (TGFbeta) is the predominant cytokine in all forms of fibrotic reactions. As well as being secreted by immune modulators of fibrosis such as macrophages, it is involved in an autocrine feedback loop of fibroblast stimulation whose regulation is still poorly understood. We wished to gain some insight into the mechanisms of the fibroblast response to TGFbeta.

Conformational flexibility of phycocyanobilin: an AM1 semiempirical study.

Semiempirical AM1 studies on phycocyanobilin, the most abundant chromophore in the light-harvesting phycobiliproteins and a suitable model of the phytochrome chromophore, have been carried out. For the all-Z isomer, the structures and energies of all possible conformers, which arise from rotation about the single bonds of the exocyclic methine bridges, were calculated. In addition, the rotational barriers between the different conformers were deduced from the computed energy hypersurfaces.

Apoptosis-inducing membrane vesicles. A novel agent with unique properties.

The CD95 ligand (FasL) transmembrane protein is found on activated T cells and cells outside the immune system. A well-known turnover process of membrane FasL is mediated by matrix metalloproteinase, which generates soluble FasL (sFasL). Here, we demonstrate that membrane FasL turnover occurs effectively through the release of membrane vesicles.

First steps in the phytochrome phototransformation: a comparative femtosecond study on the forward (Pr --> Pfr) and back reaction (Pfr --> Pr).

The primary light-induced events in the reversible Pr right harpoon over left harpoon Pfr phototransformation are investigated by femtosecond absorption spectroscopy using a pump-probe technique. After the selective electronic excitation of Pr and Pfr with pulses at 610 and 730 nm, respectively, the transient absorption spectra were measured as a function of the delay time and subjected to a global fit analysis. As a result of this analysis, the decay-associated spectra of the kinetic components involved in the formation of the first photoproducts in the forward and back reaction are obtained.