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Structure of human lactoferrin: crystallographic structure analysis and refinement at 2.8 A resolution
B F Anderson1, H M Baker, G E Norris
1Department of Chemistry and Biochemistry, Massey University, Palmerston North, New Zealand.
Journal of Molecular Biology
|October 20, 1989
Summary
This study refines the crystallographic structure of human lactoferrin, revealing detailed insights into its iron-binding sites and structural domains. The findings clarify protein interactions and anion binding, enhancing our understanding of lactoferrin
Area of Science:
- Structural Biology
- Biochemistry
- Protein Crystallography
Background:
- Human lactoferrin is an iron-binding glycoprotein with diverse biological functions.
- Previous structural data lacked atomic resolution for key functional sites.
Purpose of the Study:
- To refine the crystallographic structure of human lactoferrin to high resolution.
- To elucidate the precise atomic details of iron and anion binding sites.
- To clarify the structural basis of lactoferrin's functional properties.
Main Methods:
- Crystallographic refinement using restrained least squares methods.
- Utilized a 3.2 A resolution map phased by multiple isomorphous replacement and solvent flattening.
- Model rebuilding incorporated experimental phases and phases from a partial model.
Main Results:
- Refined structure at 2.8 A resolution, including 681 amino acid residues, two Fe3+, and two CO3(2-).
- Identified two similar lobes, each with two dissimilar alpha/beta domains, and clarified secondary/tertiary interactions.
- Detailed the iron-binding site, revealing coordination by Tyr, Asp, His, and carbonate, and identified potential anion-binding pockets.
Conclusions:
- The refined structure provides unprecedented atomic detail of human lactoferrin.
- Structural insights explain anion binding mechanisms and acid stability.
- The findings contribute to understanding lactoferrin's role in iron homeostasis and immunity.