Conformational studies on subfragments from the Fc region of human immunoglobulin G

• Published in: Biochemical and biophysical research communications Vol. 47; no. 2; pp. 512 - 516
• Main Authors: Dorrington, K.J., Bennich, H., Turner, M.W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28.04.1972
• Subjects: Chromatography, Gel; Circular Dichroism; Electrophoresis; Humans; Immunoglobulin Fc Fragments - analysis; Immunoglobulin G - analysis; Papain; Protein Conformation; Spectrophotometry, Ultraviolet; Trypsin
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/0006-291X(72)90744-9

The circular dichroism (CD) spectrum of Fc fragment from Immunoglobulin G is dominated by a negative band at 217 nm. In contrast, pFc′, a subfragment of Fc representing a dimer of the C H3 domains of heavy chain, showed no minimum at this wavelength but rather at 224 nm. Marked differences were also apparent in the aromatic side chain CD region above 250 nm. A papain-produced fragment of Fc related to but smaller than pFc′ showed CD properties quantitatively and qualitatively different from pFc′. Studies with a tryptic fragment of pFc′ indicated that the conformational differences between pFc′ and Fc′ were primarily related to the proteolytic removal of a C-terminal tridecapeptide in the Fc′ sequence relative to pFc′. A comparison of the CD spectra of pFc′ with the constant region domain of light chain indicates that despite marked sequence homology between domains their conformations may be quite different.