Use this URL to cite or link to this record in EThOS:
Title: Haemoglobin binding to red cell membranes under physiological conditions
Author: Welbourn, Elizabeth
Awarding Body: University of Essex
Current Institution: University of Essex
Date of Award: 2012
Availability of Full Text:
Access from EThOS:
Irreversible binding of denatured haemoglobin to membranes has been implicated as part of the macrophage recognition system for the removal of senescent cells from the circulation. Most work in this area has used haemolytic agents or unstable pathological haemoglobins to initiate binding, the haemoglobin forming redox inactive hemichromes. In contrast, this thesis explores milder oxidising conditions that are closer to those found in vivo. Oxidised (ferric +3) haemoglobin was shown to bind covalently to red cell membrane proteins, even at 4°C. Adding hydrogen peroxide to form higher oxidation states (+4 or +5) induced greater binding. Ferric haemoglobin bound to cytoskeleton band 3 node proteins, with 50% of the binding involving disulphide bridges. With hydrogen peroxide present a wider variety of cytoskeleton proteins was involved, with only 33% of binding via disulphide bridges. Bound haemoglobin demonstrated redox activity, including initiating lipid peroxidation in liposomes and spontaneous autoxidation. Haemoglobin in solution at low concentrations (nM) shows a single rate for CO recombination. Flash photolysis showed that bound haemoglobin exhibited two phases, with similar kinetics to those shown by haemoglobin in solution at higher concentrations, suggesting the bound protein could still undergo a dynamic dimer/tetramer equilibrium. These findings alter our understanding of the role of haemoglobin in red cell senescence. We propose that the primary binding event results in haemoglobin bound in the ferric state, which remains redox active. It is able to initiate further peroxidative damage to the cell, only later decaying into hemichromes. This has implications both for the basic mechanism of senescence and the prevention of storage lesions in red cells used for transfusion.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available