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/sup 13/C NMR studies of /sup 13/C methylated Fc fragments

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:5234094
; ;

Little is known about the structure-function relationships in the Fc portion of the IgG molecule, even though it mediates a number of physiological effector functions. This study is focused on the characterization of the lysine residues because of their potential involvement in Fc effector interactions. The Fc fragments were reductively /sup 13/C-methylated and /sup 13/C NMR was used to characterize the dimethylamino groups. Dimethylamino groups have properties generally representative of native amino groups. In addition, the chemical shifts of the /sup 13/C NMR resonances are quite sensitive to the local environment of the dimethylamino moiety. All of the lysyl amino groups of the Fc fragments were modified as indicated by the relative areas of the dimethyllysyl and the N-terminal dimethylamino /sup 13/C NMR resonances. The pH dependences of the fragments were determined and seven unique titration curves were resolved for Fc-Cohn while eight curves were obtained for Fc-Tu. The calculated pKa values from these titration curves fell in the range of 9.6 to 10.3 for both fragments. Several of the titrating resonances are from single lysyl residues. Current efforts are directed toward assignment of the /sup 13/C NMR resonances to specific lysyl residues and toward further characterization of their thermodynamic properties.

Research Organization:
Case Western Reserve Univ., Cleveland, OH
OSTI ID:
5234094
Report Number(s):
CONF-8606151-
Journal Information:
Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:6; ISSN FEPRA
Country of Publication:
United States
Language:
English

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Related Subjects

550201* -- Biochemistry-- Tracer Techniques
550600 -- Medicine
59 BASIC BIOLOGICAL SCIENCES
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHEMICAL SHIFT
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
LYSINE
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PH VALUE
RESIDUES
RESONANCE
SPECTRA
STABLE ISOTOPES
STRUCTURE-ACTIVITY RELATIONSHIPS