Antibody catalysis of the oxidation of water.
Science
; 293(5536): 1806-11, 2001 Sep 07.
Article
em En
| MEDLINE
| ID: mdl-11546867
ABSTRACT
Recently we reported that antibodies can generate hydrogen peroxide (H2O2) from singlet molecular oxygen (1O2*). We now show that this process is catalytic, and we identify the electron source for a quasi-unlimited generation of H2O2. Antibodies produce up to 500 mole equivalents of H2O2 from 1O2*, without a reduction in rate, and we have excluded metals or Cl- as the electron source. On the basis of isotope incorporation experiments and kinetic data, we propose that antibodies use H2O as an electron source, facilitating its addition to 1O2* to form H2O3 as the first intermediate in a reaction cascade that eventually leads to H2O2. X-ray crystallographic studies with xenon point to putative conserved oxygen binding sites within the antibody fold where this chemistry could be initiated. Our findings suggest a protective function of immunoglobulins against 1O2* and raise the question of whether the need to detoxify 1O2* has played a decisive role in the evolution of the immunoglobulin fold.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oxigênio
/
Água
/
Oxidantes
/
Anticorpos Catalíticos
/
Peróxido de Hidrogênio
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Science
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Estados Unidos