Linked Life Data

3500233

Source:http://linkedlifedata.com/resource/pubmed/id/3500233

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
1988-1-4
pubmed:abstractText
Immunoconjugates are semi-synthetic hybrid proteins which bear great promise to become a new generation of anti-tumor agents. While many immunoconjugates have been shown to be selectively cytotoxic in in vitro model systems, dramatic in vivo anti-tumor effects have not been reported. To improve the activity of immunoconjugates, careful structure-function analyses have to be performed. We report here such an analysis for immunoconjugates consisting of a monoclonal anti-tumor antibody (MoAb) and cobra venom factor (CVF), the complement-activating glycoprotein from cobra venom, synthesized with the heterobifunctional crosslinking reagent N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP). It is shown that a reaction mixture after protein coupling contains free MoAb and CVF as well as hybrid proteins of different compositions (dimers (MoAb-CVF), trimers (MoAb2-CVF, MoAb-CVF2), tetramers (MoAb-CVF3, MoAb2-CVF2, MoAb3-CVF), and some higher oligomers). While free MoAb and CVF can be removed by size exclusion chromatography, separation of different oligomeric hybrid proteins is not possible by this method. From the biochemical characterization of the hybrid proteins, which included the determination of sedimentation coefficients, recording of circular dichroism spectra with subsequent determination of secondary structure, and ultrastructural analysis by transmission electron microscopy, it was concluded that the two proteins do not undergo major structural changes upon coupling, and that the coupling of the two proteins is random with no preferential relative orientation. The functional inactivation of CVF was substantial (approximately 70%) due to both derivatization with SPDP and subsequent conjugation to the MoAb, with conjugation being relatively more inactivating than derivatization. In contrast, the binding activity of the antibody was far less susceptible to inactivation. In conclusion, our data indicate that immunoconjugate synthesis with heterobifunctional crosslinking reagents results in a mixture of heterogeneous hybrid proteins and causes substantial functional inactivation. For successful in vivo anti-tumor activity of future immunoconjugates with CVF and other protein ligands better methods for immunoconjugate synthesis will have to be developed.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0022-1759
pubmed:author
pubmed:issnType
Print
pubmed:day
23
pubmed:volume
104
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
159-72
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Antibody conjugates with cobra venom factor. Synthesis and biochemical characterization.
pubmed:affiliation
Department of Biochemistry, Georgetown University, Washington, DC 20007.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.