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SOME PROPERTIES OF CRYSTALLINE GUINEA PIG HEMOGLOBIN.
1Laboratories of The Rockefeller Institute for Medical Research.
The Journal of General Physiology
|October 30, 2009
Summary
Guinea pig hemoglobin crystals allow small molecules to pass through, suggesting spaces exist between protein molecules. These interstices, crucial for crystal structure, influence oxygen binding and reactivity.
Area of Science:
- Biophysics
- Crystallography
- Biochemistry
Background:
- Hemoglobin (Hb) is a protein responsible for oxygen transport.
- Understanding Hb crystal structure provides insights into its function.
- Previous studies have explored Hb properties in solution.
Purpose of the Study:
- To investigate the permeability of guinea pig hemoglobin crystals.
- To determine the structural basis for crystal permeability.
- To explore the influence of crystal packing on oxygen binding and reactivity.
Main Methods:
- Crystallization of guinea pig hemoglobin.
- Permeability studies using ferricyanide and hydrosulfite.
- Analysis of crystal lattice structure based on closest hexagonal packing assumptions.
- Spectroscopic analysis of ferrihemoglobin reduction.
Main Results:
- Guinea pig hemoglobin crystals are permeable to ferricyanide and hydrosulfite.
- Interstices, comprising 25% of crystal volume, facilitate diffusion.
- Heme groups are located on the globin surface, facing these interstices.
- Oxygen binding is stronger in HbO(2) crystals than in solution.
- Ferrihemoglobin reduction by activated hydrogen requires a redox dye, demonstrating H(2)O(2) formation.
Conclusions:
- Crystal lattice interstices are key to hemoglobin crystal permeability.
- Crystal packing influences hemoglobin's oxygen affinity.
- The arrangement of hemes and crystal structure impacts reactivity.
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