Ligand binding in haem-containing proteins: A chiroptical study
8 mei 2020
ONLINE Doctoraatsverdediging - -- - -- --
Organisatie / co-organisatie:
Wouter Herrebout & Christian Johannessen
ONLINE Doctoraatsverdediging Roberta Sgammato - Faculteit Wetenschappen, Departement Chemie
Globins are haem containing proteins ubiquitously expressed in all kingdoms of life, from bacteria to vertebrates. Thanks to the haem iron, globins can reversibly bind small ligands and can be involved in redox reactions. Nowadays more than 400 globins have been identified and classified into three main lineages and two structural families. Many of the recently discovered globins exhibit quite unusual structural architecture and a still unexplored mechanism of action. Revealing details about their structure-function paradigm can have an important biomedical relevance: a simple interaction between the globin haem iron with an exogenous ligand can eventually change the habits of the host organism and influence its adaptability to the environment, or in some cases its virulence. Moreover, some newly characterised globins are thought to have a neuroprotective function, hence a detailed knowledge of their mechanism of action could be beneficial for pharmacological purposes.
In the present work, we propose a spectroscopic approach to the study of haem-containing proteins, based on a combination of chiroptical techniques. In particular, we base our investigation on the use of resonance Raman optical activity (rROA) and electronic circular dichroism (ECD). While these techniques are routinely employed for the determination of the absolute configuration of natural compounds, their application to the study of the haem chromophore in globins, has been so far very poorly explored. The present thesis represents therefore a first, preliminary approach to relatively simple globins (or globin domains solely), using a non-classical spectroscopic approach. We have highlighted the capability of this methodology to detect conformational modifications of the achiral haem chromophore when placed in a protein matrix, and its fine sensitivity to small perturbations of the haem planarity induced by ligand binding. The early results show the potential of the chiroptical approach, and set the bases for a future investigation of more complex chimeric globins, via rROA and ECD.