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The reversible photocontrol of an enzyme governing blood coagulation is demonstrated. The thrombin binding aptamer (TBA), was rendered photochromic by modification with two anthracene groups. Light-triggered anthracene photodimerisation distorts its structure, inhibiting binding of the enzyme thrombin, which in turn triggers catalysis and the resulting clotting process.

The ability to discriminate between epigenetic variants in DNA is a necessary tool if we are to increase our understanding of the roles that they play in various biological processes and medical conditions. Herein, it is demonstrated how a simple two-step fluorescent probe assay can be used to differentiate all three major epigenetic variants of cytosine at a single locus site in a target strand of DNA.

The unprecedented use of anthracene photodimerization within a protein or peptide system is explored through its incorporation into a DNA-binding peptide, derived from the GCN4 transcription factor. This study demonstrates an effective and dynamic interplay between a photoreaction and a peptide-DNA assembly, with each process able to exert control over the other.

The coordination of the therapeutically interesting [AuCl(PEt(3))] to the de novo designed peptide, TRIL23C, under aqueous conditions, is reported here. TRIL23C represents an ideal model to investigate the binding of [AuCl(PEt(3))] to small proteins in an effort to develop novel gold(I) phosphine peptide adducts capable of mimicking biological recognition and targeting. This is due to the small size of TRIL23C (30 amino acids), yet stable secondary and tertiary fold, symmetric nature and the availability of only one thiol binding site. [AuCl(PEt(3))] was found to react readily with the Cys side chain in a 1:1 ratio as confirmed by UV-visible, (31)P NMR and mass spectrometry. Circular dichroism confirmed that the coiled coil structure was retained on coordination of the {Au(PEt(3))}(+) unit. Redesign of the exterior of TRIL23C based on a biologically relevant recognition sequence found in GCN4, did not alter the coordination chemistry of [AuCl(PEt(3))]. To the best of our knowledge, this represents the first report on the coordination of gold(I) phosphine compounds to de novo designed peptides, and could lead to the generation of novel gold(I) phosphine peptide therapeutics in the future., (Copyright © 2012 Elsevier Inc. All rights reserved.)