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Effect of glutaraldehyde on haemoglobin: oxidation-reduction potentials and stability
Biochemical Pharmacology
|January 15, 1986
Summary
Glutaraldehyde cross-linking of haemoglobin impacts its oxidation-reduction properties and stability. While it increases autoxidation rates and stabilizes ferrihaemoglobin against heat, it does not protect against urea denaturation, suggesting protein modification without conformation freezing.
Area of Science:
- Biochemistry
- Protein Chemistry
- Biomaterials
Background:
- Glutaraldehyde is a common cross-linking agent for haemoglobin (Hb) used in blood substitutes.
- Previous research primarily focused on oxygen binding of glutaraldehyde-modified Hb.
Purpose of the Study:
- To investigate the effects of glutaraldehyde cross-linking on the oxidation-reduction equilibria, autoxidation kinetics, and stability of Hb.
- To compare these effects across Hb cross-linked in oxy, deoxy, and ferri states.
Main Methods:
- Characterization of oxidation-reduction potentials and Bohr effects.
- Measurement of autoxidation rates under varying pH conditions.
- Assessment of thermal and urea-induced denaturation of cross-linked Hb.
Main Results:
- Glutaraldehyde cross-linking reduced oxidation-reduction potentials and homotropic effects, but the oxidation Bohr effect remained similar to native Hb.
- Autoxidation rates increased post-cross-linking, especially at alkaline pH.
- Cross-linked ferrihaemoglobin showed enhanced stability against thermal denaturation compared to oxy or deoxyhaemoglobin, but no stabilization against urea denaturation was observed.
Conclusions:
- Glutaraldehyde modifies haemoglobin chemically, potentially opening the haem pocket without significant 'conformation freezing'.
- The cross-linking process alters redox properties and autoxidation kinetics, with state-dependent stability effects.
- Glutaraldehyde cross-linking offers limited protection against urea-induced denaturation, indicating specific structural changes rather than overall rigidification.