Linked Life Data

15269209

Source:http://linkedlifedata.com/resource/pubmed/id/15269209

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
38
pubmed:dateCreated
2004-9-13
pubmed:abstractText
We report the selective catalytic cleavage of the HIV coat protein gp120, a B cell superantigen, by IgM antibodies (Abs) from uninfected humans and mice that had not been previously exposed to gp120. The rate of IgM-catalyzed gp120 cleavage was greater than of other polypeptide substrates, including the bacterial superantigen protein A. The kinetic parameters of gp120 cleavage varied over a broad range depending on the source of the IgMs, and turnover numbers as great as 2.1/min were observed, suggesting that different Abs possess distinct gp120 recognition properties. IgG Abs failed to cleave gp120 detectably. The Fab fragment of a monoclonal IgM cleaved gp120, suggesting that the catalytic activity belongs to the antibody combining site. The electrophoretic profile of gp120 incubated with a monoclonal human IgM suggested hydrolysis at several sites. One of the cleavage sites was identified as the Lys(432)-Ala(433) peptide bond, located within the region thought to be the Ab-recognizable superantigenic determinant. A covalently reactive peptide analog (CRA) corresponding to gp120 residues 421-431 with a C-terminal amidino phosphonate diester mimetic of the Lys(432)-Ala(433) bond was employed to probe IgM nucleophilic reactivity. The peptidyl CRA inhibited the IgM-catalyzed cleavage of gp120 and formed covalent IgM adducts at levels exceeding a control hapten CRA devoid of the peptide sequence. These observations suggest that IgMs can selectively cleave gp120 by a nucleophilic mechanism and raise the possibility of their role as defense enzymes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
17
pubmed:volume
279
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
39611-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Naturally occurring proteolytic antibodies: selective immunoglobulin M-catalyzed hydrolysis of HIV gp120.
pubmed:affiliation
Chemical Immunology and Therapeutics Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, Texas 77030, USA. Sudhir.Paul@uth.tmc.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.