UNIVERSITY OF MALTA
LIFE SCIENCE RESEARCH SEMINARS
Web: http://www.um.edu.mt/events/scisem/
Email: scisem@um.edu.mt
Abstract form
Title: Metal Selectivity and Specificity of Iron Superoxide Dismutase
from Escherichia coli.
Presenter: Diane Farrugia
Contact address: Department of Physiology and Biochemistry, University of
Malta, MSD2080.
Tel:
Fax:
Email: dfar0012@um.edu.mt
Presentation date: 1st July 2013
.
Abstract
The requirement of oxygen for aerobically living species necessitates protective
mechanisms that remove potentially damaging reactive oxygen species (ROS).
Superoxide dismutases (SODs) are important antioxidant metalloenzymes which
protect the essential cell structures from the superoxide radical by catalysing their
dismutation to oxygen and hydrogen peroxide.
There are four classes of SODs, grouped according to the central metal ion (Fe, Mn,
Cu/Zn, and Ni) at the active site. FeSOD and MnSOD share extensive sequence
homology rendering them nearly superimposable, with an identical metal binding
site. These two proteins can accommodate either Mn or Fe at their active sites, but
are found to be highly selective and specific for the “correct” metal. They are
inactive when the “incorrect” metal ion is artificially inserted into the active site.
During this research project, an Escherichia coli FeSOD mutant, prepared by
cloning and site-directed mutagenesis in our lab by Prof. G. J. Hunter and Dr. T.
Hunter was studied. This mutant protein, FeSOD[dblDGF], contains five amino acid
changes in its sequence to mimic those in MnSOD. The aim of this research was
therefore to obtain further knowledge with regards to selectivity for the metal and
specificity of the reaction.
Metal selectivity was investigated through metal replacement both in vivo and in
vitro, and a method was developed. Physicochemical properties were analysed to
determine metal content (ICP-MS, MP-AES), enzyme activity and thus specificity
(spectrophotometry, zymography) and structural integrity (circular dichrosim, X-Ray
crystallography).