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A doubly cross-linked human hemoglobin. Effects of cross-links between different subunits
R T Jones1, D T Shih, T S Fujita
1Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health Sciences University, Portland 97201, USA.
The Journal of Biological Chemistry
|January 12, 1996
Summary
This study created doubly cross-linked hemoglobin, modifying both beta and alpha chains. The resulting hemoglobin exhibits reduced oxygen affinity and cooperativity, offering potential for specific applications.
Area of Science:
- Biochemistry
- Protein Chemistry
- Molecular Biology
Background:
- Human hemoglobin is crucial for oxygen transport.
- Cross-linking hemoglobin modifies its functional properties.
- Previous studies established trimesyl tris(3,5-dibromosalicylate) for beta chain cross-linking.
Purpose of the Study:
- To create and characterize doubly cross-linked human hemoglobin.
- To investigate the impact of dual cross-linking on oxygen affinity and cooperativity.
- To assess modifications to the Bohr and chloride effects.
Main Methods:
- Sequential cross-linking of human deoxyhemoglobin.
- First cross-link: trimesyl tris(3,5-dibromosalicylate) targeting beta chain lysyl residues.
- Second cross-link: bis(3,5-dibromosalicyl)fumarate targeting alpha chain lysyl residues.
Main Results:
- Singly beta-chain cross-linked hemoglobin showed high oxygen affinity (P50 = 4.8 torr).
- Doubly cross-linked hemoglobin exhibited reduced oxygen affinity (P50 = 15.9 torr) compared to singly cross-linked species.
- Doubly cross-linked hemoglobin retained cooperativity (Hill coefficient = 2.3) and showed diminished Bohr and chloride effects.
Conclusions:
- Dual cross-linking significantly alters hemoglobin's oxygen-binding properties.
- The cross-link with lower intrinsic affinity appears to dominate the overall oxygen affinity.
- This doubly cross-linked hemoglobin serves as a platform for further structural and functional studies.