Genotype and soil substrate effects on the wood quality of poplar grown in a reclaimed lignite-mining area.

An understanding of the structural organisation and chemistry of the cell walls in woody tissues is crucial from the perspective of plant mechanical strength, water transportability, as well as subsequent commercial utilisation of the wood. Poplar trees (Populus sp.), grown on two reclamation substrates ("Humus" and "Sand") under the extreme soil conditions of an external coal mining spoil heap of the lignite mine in Bełchatów (Central Poland), were examined.

Isomeric mono-, di-, and tri-bromobenzo-1H-triazoles as inhibitors of human protein kinase CK2α.

To further clarify the role of the individual bromine atoms of 4,5,6,7-tetrabromotriazole (TBBt), a relatively selective inhibitor of protein kinase CK2, we have examined the inhibition (IC(50)) of human CK2α by the two mono-, the four di-, and the two tri- bromobenzotriazoles relative to that of TBBt. Halogenation of the central vicinal C(5)/C(6) atoms proved to be a key factor in enhancing inhibitory activity, in that 5,6-di-Br(2)Bt and 4,5,6-Br(3)Bt were almost as effective inhibitors as TBBt, notwithstanding their marked differences in pK(a) for dissociation of the triazole proton. The decrease in pK(a) on halogenation of the peripheral C(4)/C(7) atoms virtually nullifies the gain due to hydrophobic interactions, and does not lead to a decrease in IC(50).

Synthesis and physico-chemical properties in aqueous medium of all possible isomeric bromo analogues of benzo-1H-triazole, potential inhibitors of protein kinases.

In ongoing studies on the role of the individual bromine atoms of 4,5,6,7-tetrabromobenzotriazole (TBBt) in its relatively selective inhibition of protein kinase CK2α, we have prepared all the possible two mono-, four di-, and two tri-bromobenzotriazoles and determined their physicochemical properties in aqueous medium. They exhibited a general trend of a decrease in solubility with an increase in the number of bromines on the benzene ring, significantly modulated by the pattern of substitution. For a given number of attached bromines, this was directly related to the electronic effects resulting from different sites of substitution, leading to marked variations of pK(a) values for dissociation of the triazole proton.

Relative role of halogen bonds and hydrophobic interactions in inhibition of human protein kinase CK2α by tetrabromobenzotriazole and some C5-substituted analogues.

To examine the relative role of halogen bonding and hydrophobic interactions in the inhibition of human CK2alpha by 4,5,6,7-tetrabromobenzotriazole (TBBt), we have synthesized a series of 5-substituted benzotriazoles (Bt) and the corresponding 5-substituted 4,6,7-tribromobenzotriazoles (Br3Bt) and examined their inhibition of human CK2alpha relative to that of TBBt. The various C(5) substituents differ in size (H and CH3), electronegativity (NH2 and NO2), and hydrophobicity (COOH and Cl). Some substituents were halogen bond donors (Cl, Br), while others were fluorine bond donors (F and CF3).