Issue 11, 1996

Triazinylaniline derivatives as fluorescence probes. Part 4. Kinetics and selectivity in the reactions of N,N-diethyl-4-(dichloro-1,3,5-triazinyl)aniline with amines, amino acids and proteins relevant to fluorescence labelling

Abstract

The kinetics of reaction of the reactive triazinyl dye, N,N-diethyl-4-(dichloro-1,3,5-triazinyl)aniline with primary and secondary amines, amino acids, and the proteins bovine brain calmodulin and bovine serum albumin in aqueous media, as monitored by UV–VIS absorption spectroscopy, are reported. In general the reaction is first-order in the dye and in the substrate. Secondary aliphatic amines are more reactive than primary aliphatic amines, and a retarding influence of geminal hydroxy substituents is observed in many cases. The intrinsic reactivity of the dye towards the side chain ε-amino group of lysine is 10 times higher than that for a free N-terminal amino group. The influences of pH and temperature on reaction rates have been determined. Selectivity in reaction of the dye (TACl2) with lysine residues of calmodulin and bovine serum albumin, of 1 : 1 and ≈2 : 1 dye-protein stoichiometry, respectively, is ascribed to the dominant role played by hydrophobic interactions of dye and protein surfaces. On the basis of the kinetic evidence a three-stage mechanism is proposed and numerically evaluated. Initial rapid diffusional encounter of the dye and protein is followed by a slower ‘internalization’ of the dye in a hydrophobic pocket of the protein (activation energy 65–77 kJ mol–1). Finally, chemical adduct formation occurs in the protein interior having an activation energy of 21–36 kJ mol–1, significantly lower than that found (42–48 kJ mol–1) for reaction of dye and primary aliphatic amines in homogeneous solution.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 2, 1996, 2431-2439

Triazinylaniline derivatives as fluorescence probes. Part 4. Kinetics and selectivity in the reactions of N,N-diethyl-4-(dichloro-1,3,5-triazinyl)aniline with amines, amino acids and proteins relevant to fluorescence labelling

D. J. Cowley, J. Chem. Soc., Perkin Trans. 2, 1996, 2431 DOI: 10.1039/P29960002431

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements