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Characterization of Sickling During Controlled Automated Deoxygenation with Oxygen Gradient Ektacytometry
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Hemoglobin crystals immersed in liquid oxygen reveal diffusion channels.
James Ross Terrell1, Ryan H Gumpper2, Ming Luo3
1Department of Chemistry, Georgia State University, Atlanta, GA 30302, USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302, USA.
Biochemical and Biophysical Research Communications
|December 17, 2017
Summary
Human hemoglobin (HbA) uses internal channels for oxygen transport, not just the heme site. This discovery, aided by a new liquid oxygen method, impacts understanding of oxygen transport in diseases.
Area of Science:
- Biochemistry
- Structural Biology
- Biophysics
Background:
- Human hemoglobin (HbA) is crucial for oxygen transport.
- Oxygen binding is influenced by distal histidine (HisE7) and potential intraprotein channels.
- Understanding these mechanisms is vital for diseases affecting oxygen affinity.
Purpose of the Study:
- To investigate the role of intraprotein oxygen channels in HbA.
- To develop a novel method for crystallographic analysis of oxygen-binding proteins.
- To explore the structural basis of oxygen transport in HbA.
Main Methods:
- Developed a novel crystal immersion technique using liquid oxygen.
- Collected X-ray diffraction data from oxygen-immersed crystals.
- Analyzed structural changes and flexibility in HbA.
Main Results:
- Observed increased structural flexibility in regions consistent with postulated oxygen channels.
- Identified these flexible regions correlate with mutations affecting oxygen affinity.
- The liquid oxygen method oxidized the heme center to aquomethemoglobin.
Conclusions:
- HbA likely utilizes intraprotein channels for oxygen transport, beyond the heme site.
- This finding has implications for understanding diseases related to HbA oxygen affinity.
- The liquid oxygen immersion technique is a valuable new tool for studying oxygen-utilizing proteins.
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