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Glycera dibranchiata hemoglobin. Structure and refinement at 1.5 A resolution.
1Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218.
Journal of Molecular Biology
|November 5, 1989
Summary
The refined 1.5 A structure of a Glycera dibranchiata hemoglobin monomer reveals a unique, hydrophobic heme pocket due to leucine substitution for distal histidine. This provides insights into marine invertebrate hemoglobin function.
Area of Science:
- Biochemistry
- Structural Biology
- X-ray Crystallography
Background:
- Marine bloodworms (Glycera dibranchiata) possess complex hemoglobin systems.
- Understanding hemoglobin structure is crucial for elucidating oxygen transport mechanisms.
Purpose of the Study:
- To present the high-resolution refined structure of a Glycera dibranchiata hemoglobin monomer.
- To analyze the structural features, including heme orientation and the active site.
Main Methods:
- X-ray diffraction data collection at 1.5 A resolution.
- Molecular model refinement of protein and solvent.
- Analysis of atomic positions, bond deviations, and heme environment.
Main Results:
- Refined structure of the Glycera monomer to 1.5 A resolution with a low R-factor (12.7%).
- Detailed atomic coordinates determined with high precision.
- Identified a 'reverse' heme orientation and a hydrophobic heme pocket caused by leucine at the E7 position.
Conclusions:
- The refined structure provides a detailed atomic model of Glycera hemoglobin.
- The hydrophobic heme pocket suggests unique functional properties compared to other globins.
- Further research can explore the functional implications of this structural adaptation in marine invertebrates.