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Issue 12, 2006
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Time-resolved methods in Biophysics. 2. Monitoring haem proteins at work with nanosecond laser flash photolysis

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Abstract

Haem proteins have long been the most studied proteins in biophysics, and have become paradigms for the characterization of fundamental biomolecular processes as ligand binding and regulatory conformational transitions. The presence of the haem prosthetic group, the absorbance spectrum of which has a ligation sensitive region conveniently located in the UV-visible range, has offered a powerful and sensitive tool for the investigation of molecular functions. The central Fe atom is capable of reversibly binding diatomic ligands, including O2, CO, and NO. The Fe-ligand bond is photolabile, and a reactive unligated state can be transiently generated with a pulsed laser. The photodissociated ligands quickly rebind to the haem and the process can be monitored by transient absorbance methods. The ligand rebinding kinetics reflects protein dynamics and ligand migration within the protein inner cavities. The characterization of these processes was done in the past mainly by low temperature experiments. The use of silica gels to trap proteins allows the characterization of internal ligand dynamics at room temperature. In order to show the potential of the laser flash photolysis techniques, combined with modern numerical analysis methods, we report experiments conducted on two non-symbiotic haemoglobins from Arabidopsis thaliana. The comparison between time courses recorded on haemoglobins in solution and encapsulated in silica gels allows for the highlighting of different interplays between protein dynamics and ligand migration.

Graphical abstract: Time-resolved methods in Biophysics. 2. Monitoring haem proteins at work with nanosecond laser flash photolysis

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Publication details

The article was received on 18 Jul 2006, accepted on 25 Sep 2006 and first published on 18 Oct 2006


Article type: Perspective
DOI: 10.1039/B610236K
Photochem. Photobiol. Sci., 2006,5, 1109-1120

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    Time-resolved methods in Biophysics. 2. Monitoring haem proteins at work with nanosecond laser flash photolysis

    S. Abbruzzetti, S. Bruno, S. Faggiano, E. Grandi, A. Mozzarelli and C. Viappiani, Photochem. Photobiol. Sci., 2006, 5, 1109
    DOI: 10.1039/B610236K

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