engleski

An Electron Paramagnetic Resonance Study of Copper(II) Complexes with L-a-Amino Acids

In order to investigate importance of a conformation of the amino acid side chains in water binding or water release to the copper(II) ion in complexes with long aliphatic side chains the temperature dependece of Brownian motion of aquabis[N, N-dimetyl-L-alpha-alaninato]copper(II) and aquabis[N, N-dimetyl-L-alpha-isoleucinato]copper(II) was studied by EPR spectroscopy. The reorientation correlation time, tau, describing Browniain motion of the studied complexes dissolved in different solvents was calculated from the analysis of the EPR spectra. Linear temperature dependece of tau on viscosity to temperature ratio obtained for the alaninato complex suggested one conformation of the aquacomplex in the examined temperature interval. More complex temperature dependence of tau on viscosity/T obtained for the isoleucinato complex, suggests a conformation change of the amino acid side chains above 300 K concomitant with the release of the apical water molecule from the copper(II) ion coordination sphere.

amino acids; copper(II) complexes; Brownian motion; EPR

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