Precise determination of the orientation of the Dzialoshinskii-Moriya vector in kappa-(BEDT-TTF)2Cu[N(CN)(2)]Cl.

A novel electron spin-reorientation transition is discovered by 13C NMR in the quasi-two-dimensional organic antiferromagnet kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl. The spin reorientation occurs as an external field is swept through the orientation of the characteristic vector of the Dzialoshinskii-Moriya (DM) interaction, thus providing a precise determination of the orientation of the DM vector. Such a spin reorientation could help to characterize the DM interaction in other antiferromagnetic systems.

Design and spectroscopic characterization of peptide models for the plastocyanin copper-binding loop.

The Cu(II)- and Co(II)-binding properties of two peptides, designed on the basis of the active site sequence and structure of the blue copper protein plastocyanin, are explored. Peptide BCP-A, Ac-Trp-(Gly)(3)-Ser-Tyr-Cys-Ser-Pro-His-Gln-Gly-Ala-Gly-Met-(Gly )(3)-His-(Gly)(2)-Lys-CONH(2), conserves the Cu-binding loop of plastocyanin containing three of the four copper ligands and has a flexible (Gly)(3) linker to the second His ligand. Peptide BCP-B, Ac-Trp-(Gly)(3)-Cys-Gly-His-Gly-Val-Pro-Ser-His-Gly-Met-Gly-CONH(2), contains all four blue copper ligands, with two on either side of a beta-turn.