Linked Life Data

9799110

Source:http://linkedlifedata.com/resource/pubmed/id/9799110

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1998-11-10
pubmed:abstractText
The topology of the binding site has been studied for two monoclonal antibodies 13G10 and 14H7, elicited against iron(III)-alpha,alpha,alpha,beta-meso-tetrakis(ortho-carboxyphenyl)porph yrin [alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin]], and which exhibit in the presence of this alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] cofactor a peroxidase activity. A comparison of the dissociation constants of the complexes of 13G10 and 14H7 with various tetra-aryl-substituted porphyrin has shown that: (a) the central iron(III) atom of alpha,alpha,alpha,beta-Fe[(o-COOHPh)4-porphyrin] is not recognized by either of the two antibodies; and (b) the ortho-carboxylate substituents of the meso-phenyl rings of alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] are essential for the recognition of the porphyrin by 13G10 and 14H7. Measurement of the dissociation constants for the complexes of 13G10 and 14H7 with the four atropoisomers of (o-COOHPh)4-porphyrinH2 as well as mono- and di-ortho-carboxyphenyl-substituted porphyrins suggests that the three carboxylates in the alpha, alpha, beta position are recognized by both 13G10 and 14H7 with the two in the alpha, beta positions more strongly bound to the antibody protein. Accordingly, the topology of the active site of 13G10 and 14H7 has roughly two-thirds of the alpha,alpha,alpha,beta-Fe[(o-COOHPh)4-porphyrin] cofactor inserted into the binding site of the antibodies, with one of the aryl ring remaining outside. Three of the carboxylates are bound to the protein but no amino acid residue acts as an axial ligand to the iron atom. Chemical modification of lysine, histidine, tryptophan and arginine residues has shown that only modification of arginine residues causes a decrease in both the binding of alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] and the peroxidase activity of both antibodies. Consequently, at least one of the carboxylates of the hapten is bound to an arginine residue and no amino acids such as lysine, histidine or tryptophan participate in the catalysis of the heterolytic cleavage of the O-O bond of H2O2. In addition, the amino acid sequence of both antibodies not only reveals the presence of arginine residues, which could be those involved in the binding of the carboxylates of the hapten, but also the presence of several amino acids in the complementary determining regions which could bind other carboxylates through a network of H bonds.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
257
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
121-30
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Active site topology of artificial peroxidase-like hemoproteins based on antibodies constructed from a specifically designed ortho-carboxy-substituted tetraarylporphyrin.
pubmed:affiliation
Université René Descartes, URA 400 CNRS, Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Paris, France.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't