Glowing marks: A new class of protein stains, the pyrylium dyes, undergo a strong color change (typically from blue to red, see picture) on covalently binding to proteins. While the free stains are almost nonfluorescent, the protein‐conjugated forms are highly fluorescent. The dyes do not alter the charge of a protein, and thus do not change its electrophoretic properties. The stains also can be used in quantitative protein assays.

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The interaction of cyanines with nucleic acids is accompanied by intense changes of their optical properties. Consequently these molecules find numerous applications in biology and medicine. Since no detailed information on the binding mechanism of DNA/cyanine systems is available, a T-jump investigation of the kinetics and equilibria of binding of the cyanines Cyan40 [3-methyl-2-(1,2,6-trimethyl-4(1H)pyridinylidenmethyl)-benzothiazolium ion] and CCyan2 [3-methyl-2-[2-methyl-3-(3-methyl-2(3H)-benzothiazolylidene)-1-propenyl]-benzothiazolium ion] with CT-DNA is performed at 25 degrees C, pH 7 and various ionic strengths. Bathochromic shifts of the dye absorption band upon DNA addition, polymer melting point displacement (DeltaT = 8-10 degrees C), site size determination (n = 2), and stepwise kinetics concur in suggesting that the investigated cyanines bind to CT-DNA primary by intercalation. Measurements with poly(dA-dT).poly(dA-dT) and poly(dG-dC).poly(dG-dC) reveal fair selectivity of CCyan2 toward G-C basepairs. T-jump experiments show two kinetic effects for both systems. The binding process is discussed in terms of the sequence D + S left arrow over right arrow D,S left arrow over right arrow DS(I) left arrow over right arrow DS(II), which leads first to fast formation of an external complex D,S and then to a partially intercalated complex DS(I) which, in turn, converts to DS(II), a more stable intercalate. Absorption spectra reveal that both dyes tend to self-aggregate; the kinetics of CCyan2 self-aggregation is studied by T-jump relaxation and the results are interpreted in terms of dimer formation.

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Serine/threonine protein kinase CK2 controls vast variety of fundamental processes in cell life; however, despite long period of study, its functional role is not completely determined. CK2 has a significant pathogenic potential and its activity is strictly associated with the development of various kinds of disorders. There are a growing number of facts that inhibitors of CK2 could be used as pharmaceutical agents for the cancer treatment, viral infections, and inflammatory diseases. In this article, we report structural and biological data on the novel synthetic flavonol derivatives, 3-hydroxy-4'-carboxyflavones, possessing a high inhibitory activity toward CK2. With the aid of combinatorial organic synthesis, molecular modeling techniques and biochemical in vitro tests, we studied the structure-activity relationships of flavonol derivatives and developed binding model describing their key intermolecular interactions with the CK2 ATP-binding site. Obtained data show that the synthetic 3-hydroxy-4'-carboxyflavones possess the highest activity among flavonol inhibitors of CK2 known till date.