Human IgG1 hinge fragmentation as the result of H2O2-mediated radical cleavage.
J Biol Chem
; 284(51): 35390-402, 2009 Dec 18.
Article
em En
| MEDLINE
| ID: mdl-19850927
ABSTRACT
Hinge cleavage of a recombinant human IgG1 antibody, generated during production in a Chinese hamster ovary cell culture, was observed in the purified material. The cleavage products could be reproduced by incubation of the antibody with H(2)O(2) and featured complementary ladders of the C- and N-terminal residues (Asp(226)-Lys(227)-Thr(228)-His(229)-Thr(230)) in the heavy chain of the Fab domain and the upper hinge of one of the Fc domains, respectively. Two adducts of +45 and +71 Da were also observed at the N-terminal residues of some Fc fragments and were identified as isocyanate and alpha-ketoacyl derivatives generated by radical cleavage at the alpha-carbon position through the diamide and alpha-amidation pathways. We determined that the hinge cleavage was initiated by radical-induced breakage of the disulfide bond between the two hinge cysteines at position 231 (Cys(231)-Pro-Pro-Cys-Pro), followed by the formation of a thiyl radical (Cys(231)-S(*)) on one cysteine and sulfenic acid (Cys(231)-SOH) on the other. The location of the initial radical attack and the critical role of Cys(231) were demonstrated by the observation that 5,5-dimethyl-1-pyrroline N-oxide only reacted with the Cys(231) radical and completely blocked hinge cleavage, suggesting the necessity of an electron/radical transfer from the Cys(231) radical to the hinge residues where cleavage was observed. As a precursor of hydroxyl radicals, H(2)O(2) is widely produced in healthy cells and tissues and therefore could be the source for the radical-induced fragmentation of human IgG1 antibodies in vivo.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Imunoglobulina G
/
Fragmentos Fc das Imunoglobulinas
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Peróxido de Hidrogênio
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article