Publication Date:
2001-09-08
Description:
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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wentworth , P Jr -- Jones, L H -- Wentworth, A D -- Zhu, X -- Larsen, N A -- Wilson, I A -- Xu, X -- Goddard , W A 3rd -- Janda, K D -- Eschenmoser, A -- Lerner, R A -- CA27489/CA/NCI NIH HHS/ -- GM43858/GM/NIGMS NIH HHS/ -- HD 36385/HD/NICHD NIH HHS/ -- New York, N.Y. -- Science. 2001 Sep 7;293(5536):1806-11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11546867" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Antibodies, Catalytic/chemistry/*metabolism
;
Binding Sites
;
Catalysis
;
Conserved Sequence
;
Crystallography, X-Ray
;
Humans
;
Hydrogen Peroxide/*metabolism
;
Kinetics
;
Models, Molecular
;
Oxidants/chemistry/*metabolism
;
Oxidation-Reduction
;
Oxygen/*metabolism
;
Protein Conformation
;
Singlet Oxygen
;
Spectrometry, Mass, Electrospray Ionization
;
Thermodynamics
;
Tryptophan/metabolism
;
Ultraviolet Rays
;
Water/*chemistry/*metabolism
;
Xenon/metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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