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Phosphocholine binding immunoglobulin Fab McPC603. An X-ray diffraction study at 2.7 A.
Journal of Molecular Biology
|August 20, 1986
Summary
The crystal structure of a mouse myeloma protein (McPC603) was refined, revealing a sulfate ion at the phosphocholine binding site. This provides insights into antibody-antigen interactions and protein structure.
Area of Science:
- Structural biology
- Immunology
- Biochemistry
Background:
- McPC603 is a mouse myeloma protein known to bind phosphocholine.
- Understanding the structure of antibody fragments (Fab) is crucial for deciphering antigen recognition.
Purpose of the Study:
- To refine the crystal structure of the McPC603 Fab fragment at high resolution.
- To investigate the binding site interactions, particularly with phosphocholine.
Main Methods:
- X-ray crystallography at 2.7 A resolution.
- Restrained least-squares refinement.
- Molecular modeling techniques.
Main Results:
- The overall Fab structure was confirmed, with an elbow bend angle of 133 degrees.
- Refinement led to adjustments in loop structures.
- A sulfate ion was identified occupying the phosphocholine phosphate binding site.
Conclusions:
- The refined structure provides a detailed view of the McPC603 Fab.
- The presence of a sulfate ion suggests its role in mimicking the phosphate group of phosphocholine at the binding site.
- This structural information aids in understanding antibody-antigen interactions at a molecular level.