Crystallographic refinement and atomic models of a human Fc fragment and its complex with fragment B of protein A from Staphylococcus aureus at 2.9- and 2.8-A resolution.Deisenhofer, J.
(1981) Biochemistry 20: 2361-2370
- PubMed: 7236608
- Primary Citation of Related Structures:
- PubMed Abstract:
- Crystallographic Structural Studies of a Human Fc Fragment. II. A Complete Model Based on a Fourier Map at 3.5 Angstroms Resolution
Deisenhofer, J., Colman, P.M., Epp, O., Huber, R.
(1976) Hoppe Seylers Z Physiol Chem 357: 1421
- Crystallographic Structural Studies of a Human Fc-Fragment. I. An Electron-Density Map at 4 Angstroms Resolution and a Partial Model
Deisenhofer, J., Colman, P.M., Huber, R., Haupt, H., Schwick, G.
(1976) Hoppe Seylers Z Physiol Chem 357: 435
- X-Ray Studies on Antibody Fragments
Colman, P.M., Epp, O., Fehlhammer, H., Bode, W., Schiffer, M., Lattman, E.E., Jones, T.A.
(1974) FEBS Lett 44: 194
The model of human Fc fragment was refined at 2.9-A resolution. Two different automated procedures for crystallographic refinement were used [Deisenhofer, J., & Steigemann, W. (1975) Acta Crystallogr., Sec. B B31, 238; Jack, A., & Levitt, M. (1978) Acta Crystallogr ...
The model of human Fc fragment was refined at 2.9-A resolution. Two different automated procedures for crystallographic refinement were used [Deisenhofer, J., & Steigemann, W. (1975) Acta Crystallogr., Sec. B B31, 238; Jack, A., & Levitt, M. (1978) Acta Crystallogr., Sect. A A34, 931]. The final R value is 0.22. The dimer of CH3 domains closely resembles the CH1-CL aggregate in Fab fragments. There is no contact between CH2 domains. The contact between CH2 and CH3 domains has about one-third of the size of the CH3-CH3 contact. The carbohydrate, a branched chain of nine hexose units, covers parts of the C-contact face of the CH2 domain, shielding hydrophobic residues on this surface. Six atoms of the carbohydrate are within hydrogen-bonding distance of atoms in the CH2 domain. Crystallographic refinement of the complex between Fc fragment and fragment B of protein A from Staphylococcus aureus reduced the R value of the model is 0.24. A major part of the structure of fragment B consists of two alpha helics; the rest of the polypeptide chain is folded irregularly. In the crystal, fragment B forms two contacts with Fc fragment molecules. Contact 1 involves residues from both helices of fragment B, and residues from the CH2 and CH3 domains of FC, and is predominantly hydrophobic. Contact 2 is smaller than contact 1. Residues from the second helix and adjacent residues of fragment B and residues only from the CH3 domain of Fc contribute to contact 2. The nature of contact 2 is mainly polar and includes a sulfate ion. There are strong arguments that contact 1 is the fragment B-Fc contact formed in solution under physiological conditions, while contact 2 is a crystal contact.
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