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Rotational correlation times of 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy spin label with respect to heme and nonheme proteins

Domenii publicaţii > Fizica + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: S.Cavalu, G.Damian

Editorial: ACS Publications Paragon System, Biomacromolecules, 4,6, p.1630-1635, 2003.


Noncovalent spin labelled proteins (ovalbumin, bovine serum albumin, hemoglobin and cytochrome c) were investigated in order to follow the different type of interactions between the nitroxide radical of 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy spin label and functional groups of heme and nonheme proteins as well as the pH influence on molecular motion of the label with respect to these proteins. EPR spectra were recorded at room temperature and the computer simulation analysis of spectra was made in order to obtain the magnetic parameters. Noncovalent labeling of proteins can give valuable informations on the magnetic interaction between the label molecule and the paramagnetic center of the proteins. The relevance of this interaction can be obtained from lineshape analysis: computer simulation for nonheme proteins assume a Gaussian lineshape, while for heme proteins is assumed a weighted sum of Lorentzian and Gaussian components. In the framework of the “moderate jump diffusion” model for rotational diffusion, the rotational correlation time is strongly influenced by pH, due to the electrostatic interactions and hydrogen bonding

Cuvinte cheie: EPR, spin label, bovine serum albumin, ovalbumin, haemoglobin, cytochrome c