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Reactive iron species in biological fluids activate the iron-sulphur cluster of aconitase
S Mumby1, M Koizumi, N Taniguchi
1Department of AICU, Royal Brompton Hospital, National Heart and Lung Institute, Imperial College of Science Technology and Medicine, London, UK.
Abstract:
Low molecular mass iron (LMrFe) can appear in plasma when the transferrin becomes fully iron loaded. Such iron poses a risk factor for oxidative damage, and for microbial virulence. A previous novel approach to the detection and measurement of LMrFe in plasma was the use of the iron-binding properties of the glycopeptide antitumour antibiotic bleomycin and its ability to degrade DNA in the presence of oxygen, bound iron, and an iron reducing agent. Since bleomycin is a non-physiological ligand with iron-binding and redox cycling properties, it has been suggested that it may not be a valid biological model for detecting and measuring LMrFe. To address these concerns we have developed a biological approach to the detection and measurement of LMrFe based on the activation of iron-requiring aconitase. Parallel measurements, in a variety of clinical conditions in which there was a complete saturation of the plasma transferrin, showed that the bleomycin assay and the aconitase assay can give similar results for LMrFe.
Insights
Low molecular mass iron (LMrFe) in plasma is linked to oxidative damage. A new biological aconitase assay for LMrFe measurement shows similar results to the bleomycin assay, validating a more physiological approach.
Area of Science:
- Biochemistry
- Clinical Chemistry
- Molecular Biology
Background:
- Low molecular mass iron (LMrFe) in plasma presents risks for oxidative damage and microbial virulence.
- The transferrin protein becomes fully iron-loaded, leading to LMrFe presence.
- Previous detection methods using bleomycin have raised concerns about their biological validity.
Purpose of the Study:
- To develop and validate a biological approach for detecting and measuring LMrFe in plasma.
- To address concerns regarding the non-physiological nature of the bleomycin assay.
- To compare the results of a novel biological assay with the established bleomycin assay.
Main Methods:
- Development of a biological assay for LMrFe detection based on iron-requiring aconitase activation.
- Parallel measurement of LMrFe using both the aconitase assay and the bleomycin assay.
- Analysis of plasma samples from various clinical conditions with saturated transferrin.
Main Results:
- The novel aconitase assay provides a biological method for LMrFe detection.
- Measurements using the aconitase assay showed comparable results to the bleomycin assay.
- The findings support the validity of the aconitase-based method for LMrFe assessment.
Conclusions:
- A biological approach using aconitase activation is a valid method for measuring plasma LMrFe.
- The aconitase assay offers a more physiologically relevant alternative to the bleomycin assay.
- This study validates a new tool for assessing iron-related risks in clinical settings.