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1fc1
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(New page: 200px<br /> <applet load="1fc1" size="450" color="white" frame="true" align="right" spinBox="true" caption="1fc1, resolution 2.9Å" /> '''CRYSTALLOGRAPHIC REF...)
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Revision as of 14:44, 12 November 2007
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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-ANGSTROMS RESOLUTION
Overview
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.
About this Structure
1FC1 is a Single protein structure of sequence from [1]. Full crystallographic information is available from OCA.
Reference
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, Biochemistry. 1981 Apr 28;20(9):2361-70. PMID:7236608
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