INVESTIGADORES
BRONDINO Carlos Dante
congresos y reuniones científicas
Título:
CW EPR as a tool to study paramagnetic centers: from simple inorganic systems to complex macromolecules
Autor/es:
CARLOS D. BRONDINO
Lugar:
Rosario
Reunión:
Workshop; Workshop Frontiers in Magnetic Resonance, from Materials to Biological Systems; 2013
Institución organizadora:
IBR-UNR
Resumen:
CW EPR as a tool to study paramagnetic centers: from
simple inorganic systems to complex macromolecules
Carlos D. Brondino
Departamento de Física, Facultad de Bioquímica y Ciencias
Biológicas, Universidad Nacional del Litoral, Campus Universitario, S3000ZAA Santa
Fe, Argentina
e-mail
brondino@fbcb.unl.edu.ar
Continuous wave Electron Paramagnetic Resonance (CW EPR) is a
spectroscopic technique extensively employed in the physicochemical characterization
of simple inorganic systems and redox enzymes that contain paramagnetic centers
in their structures. Since its beginnings by ~1944, CW EPR was mainly used to
evaluate the tensorial magnitudes associated with the anisotropic and isotropic
interactions that govern the magnetic resonance phenomenon in simple inorganic/organic
systems and to understand how the magnetic interactions between the paramagnetic
centers modulate the spectral properties of the isolated ions [1]. In this
line, we will analyze some examples of mononuclear and dinuclear inorganic
systems studied by single crystal CW EPR to show the potential capability of
the technique in the characterization of simple paramagnetic systems.
The use of CW EPR in the characterization of more complex systems, as is
the case of redox enzymes that present paramagnetic centers in their structure,
is relatively more recent and can be considered as an extension of the
experience gained with the above mentioned simpler systems. The redox enzymes
we will analyze may include distinct type of redox
centers (usually situated ~ 10-20 Å away) connected by long chemical pathways
which are involved in electron transfer processes [2]. In addition, despite the
long both distances and chemical paths, they can present weak magnetic
couplings produced by spin-spin interactions such as dipolar and isotropic
exchange [2,3]. We will discuss how CW EPR can be advantageously used to
determine intercenter distances, to assign the EPR active centers with those of
the structure, to evaluate the integrity of the electron transfer pathways in
distinct protein conditions, and how the technique can be used to obtain
structural information that cannot be obtained with conventional structural
techniques.
[1] a) N. I. Neuman, M. Perec, P. J. González, M. C. G. Passeggi, A. C. Rizzi,
and C. D. Brondino Journal of Physical Chemistry A 2010,
114, 13069-13075. b) N. I. Neuman, V. G. Franco, F. M. Ferroni, R.
Baggio, M. C. G. Passeggi, A. C. Rizzi, and C. D. Brondino Journal
of Physical Chemistry A 2012, 116, 12314-12320.
[2] C. D. Brondino, M. G. Rivas, M. J. Romão, J. J. G. Moura,
I. Moura, Accounts of Chemical Research,
2006, 39, 788-796.
[3] P. J. González, G. I. Barrera, A. C. Rizzi, J. J. G.
Moura, M. C. G. Passeggi, C. D. Brondino Journal
of Inorganic Biochemistry 2009, 103, 1342-1346.