Monoclonal immunoglobulin G augments hydrolysis of an ester of the homologous hapten

Kohen, F.; Kim, J.B.; Lindner, H. R.; Eshhar, Zelig; Green, B.

doi:10.1016/0014-5793(80)80842-8

Cited by 63 publications

(20 citation statements)

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“…It might be argued that the activity we observe is due to arbitrary structures of the combining site that are independent of transition state stabilization. Previous reports of antibody enhanced ester hydrolysis have proposed that nucleophilic groups at or near the combining site of ordinary anti-hapten IgG are responsible for the observed esterolysis rates (7)(8)(9). However, the kinetic parameters show such reactions are at least two orders of magnitude slower (kob5, 0.0052-0.014 min-) than those we report, even though homologous haptenic esters seem to bind as well or better than the natural haptens.…”

Section: Discussioncontrasting

confidence: 76%

“…Sporadic attempts to introduce reactive groups into an antibody's combining site have been unsuccessful (6). Some monoclonal antibodies are reported to be fortuitously endowed with nucleophilic residues that allow a reaction with an activated ester appendage on a homologous hapten recognized by the antibody (7)(8)(9). In these cases, the rate of acylation of the nucleophile is presumably accelerated by its proximity to a binding site of the haptenic fragment.…”

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confidence: 99%

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Chemical reactivity at an antibody binding site elicited by mechanistic design of a synthetic antigen.

Tramontano

Janda

Lerner

1986

Proc. Natl. Acad. Sci. U.S.A.

105

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Monoaryl phosphonate esters, designated as analogs of the transition state in the hydrolysis of carboxylic esters, were synthesized and used as haptens to generate specific monoclonal antibodies. Some of these antibodies react with cognate aryl carboxylic esters to release a fluorescent alcohol. The reaction appears to be stoichiometric; however, the activity is slowly regenerated under alkaline conditions or by treatment with hydroxylamine. Specificity is rigorous for esters ofp-trifluoroacetamidophenylacetic acid, demonstrating a structural correspondence with the phosphonate hapten.Saturation kinetics are observed and kinetic parameters (km., V.., and K.) are reported. The haptenic phosphonate is a competitive inhibitor of the reaction (K;, 35 nM); whereas the carboxylate product of ester hydrolysis is a less effective inhibitor (Ki, ca. 7500 nM). Chemical modification of side chain groups in the protein show a partial reduction in activity on acylation of lysine or nitration of tyrosine and a dramatic quenching upon modification of histidine. The evidence is discussed in terms of a mechanism in which amino acids of the antibody combining site participate in nucleophilic and/or general base catalysis. The properties of this system suggest that it is an example of enzymic transacylation where a deacylation step is not catalyzed. The possibility of deriving enzymic function from immunological specificity through this approach is advanced.The immune system is the most prolific source of receptor molecules known; yet, it remains largely unexploited for the study of the relationship of ligand binding to enzymic function. Antibodies offer the ability to specify binding interactions toward any molecule of theoretical interest, and the consequences of that interaction may then be investigated. The central tenet of biological catalysis ascribes enzymic rate accelerations to the changes in binding interactions along a reaction coordinate such that energy of binding, and thus stabilization ofthe complex, increases as bound substrates or products approach the bound transition state (1, 2). Evidence for this theory comes from the observation that substances that are thought to model the presumed transition states are often strongly bound to the enzymes as competitive inhibitors (3,4). Given the availability oftransition state analogs and the diversity of immunological receptors, one can ask whether it is possible to derive a chemical function from a pure binding function by selecting an antibody-antigen pair to define the optimal binding in a transition-state receptor complex.Immunological binding has been recognized as a potential basis for experimentally diverting binding interactions to catalytic processes (5). Sporadic attempts to introduce reactive groups into an antibody's combining site have been unsuccessful (6). Some monoclonal antibodies are reported to be fortuitously endowed with nucleophilic residues that allow a reaction with an activated ester appendage on a homologous hapten recognized by the antib...

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Section: Discussioncontrasting

confidence: 76%

mentioning

confidence: 99%

Chemical reactivity at an antibody binding site elicited by mechanistic design of a synthetic antigen.

Tramontano

Janda

Lerner

1986

Proc. Natl. Acad. Sci. U.S.A.

105

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“…4 As illustrated for the anti-VIP IgG in Table II, large gains in catalytic competence occur due to enhanced antigen binding affinity (reduced K m ). Certain polypeptides are recognized by IgM Abs present in the preimmune repertoire with high affinity, for example, the superantigens staphylococcal protein A and HIV gp120 5 are recognized by IgM Abs containing VH3 family domains with K d in the nanomolar range (46,47). Moreover, specific IgM Abs with improved affinity for individual antigens emerge by adaptive V domain maturation processes (16,48).…”

Section: Discussionmentioning

confidence: 99%

Ontogeny of Proteolytic Immunity

Planque

Bangale

Song

et al. 2004

Journal of Biological Chemistry

104

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Antigen-specific IgG Abs 1 in autoimmune and alloimmune disease are described to catalyze chemical reactions (1-3). Examples of catalytic Abs raised by routine experimental immunization with ordinary antigens have also been published (4 -7). However, no consensus has developed whether naturally occurring catalytic Abs represent rare accidents arising from adaptive sequence diversification processes or genuine enzymes with important functional roles. The major reason is that the turnover (k cat ) of antigen-specific IgG Abs is low. Some catalytic Abs express catalytic efficiencies (k cat /K m ) comparable to conventional enzymes, but this is due to high affinity recognition of the antigen ground state (reviewed in Ref. 8).Certain enzymes cleave peptide bonds by a mechanism involving the formation of a transient covalent intermediate of the substrate and a nucleophilic residue present in the active site. The nucleophiles are generated by intramolecular activation mechanisms, e.g. the activation of Ser/Thr side chain hydroxyl groups by hydrogen bonding to His residues, and can be detected by covalent binding to electrophilic phosphonate diesters (9, 10). Using these compounds as covalently reactive analogs of antigens (CRAs), we observed that IgG Abs express nucleophilic reactivities comparable to trypsin (11). Despite their nucleophilic competence, IgG Abs display low efficiency proteolysis, presumably due to deficiencies in steps occurring after formation of the acyl-Ab intermediate, viz., water attack on the intermediate and product release. Occupancy of the B cell receptor (BCR, surface Ig complexed to ␣ and ␤ subunits along with other signal transducing proteins) by the antigen drives B cell clonal selection. Proteolysis by the BCR is compatible with clonal selection, therefore, only to the extent that the release of antigen fragments is slower than the rate of antigeninduced transmembrane signaling necessary for induction of cell division. Immunization with haptens mimicking the charge characteristics of the transition state (12) has been suggested as a way to surmount the barrier to adaptive improvement of catalytic rate constants. Catalysis by designer IgG Abs obtained by these means, however, also proceeds only slowly.In mice and humans, the initial Ab repertoire consists of ϳ100 heritable VL and VH genes. Adaptive maturational processes expand the repertoire by several orders of magnitude. The initial BCR complex on the pre-B cell surface contains V-(D)-J rearranged Ig chains as a complex with surrogate L chains (reviewed in Ref. 13). Precise assignment of the B cell differentiation stage at which cell division becomes antigen-dependent is somewhat ambiguous, but it is generally believed that non-covalent antigen binding to the pre-BCR is not required for initial cell growth. / chains replace the surrogate L chain at the later stages of antigen-driven B cell differentiation, which is accompanied by diversification via somatic hypermutation processes and continued gene rearrangements (14,15). V-(D)-J gene ...

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“…This artificial fast bypass of molecular evolution, based on the induction of specific antibody repertoire in animals or by screening the phage-display libraries of antibody genes, turned out to be quite successful. The first monoclonal abzymes to be wellstudied were obtained by immunizing mice with TSAs, (8,9) which is an approach successfully developed by Lerner et al and Peter Schultz's groups. (10,11) These antibodies catalyzed a plethora of natural chemical transformations, including reactions, for which no enzyme counterparts naturally exist.…”

Section: Introductionmentioning

confidence: 99%

Catalytic antibodies: balancing between Dr. Jekyll and Mr. Hyde

et al. 2009

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The immunoglobulin molecule is a perfect template for the de novo generation of biocatalytic functions. Catalytic antibodies, or abzymes, obtained by the structural mimicking of enzyme active sites have been shown to catalyze numerous chemical reactions. Natural enzyme analogs for some of these reactions have not yet been found or possibly do not exist at all. Nowadays, the dramatic breakthrough in antibody engineering and expression technologies has promoted a considerable expansion of immunoglobulin's medical applications and is offering abzymes a unique chance to become a promising source of high-precision "catalytic vaccines." At the same time, the discovery of natural abzymes on the background of autoimmune disease revealed their beneficial and pathogenic roles in the disease progression. Thus, the conflicting Dr. Jekyll and Mr. Hyde protective and destructive essences of catalytic antibodies should be carefully considered in the development of therapeutic abzyme applications.

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Monoclonal immunoglobulin G augments hydrolysis of an ester of the homologous hapten

Cited by 63 publications

References 10 publications

Chemical reactivity at an antibody binding site elicited by mechanistic design of a synthetic antigen.

Chemical reactivity at an antibody binding site elicited by mechanistic design of a synthetic antigen.

Ontogeny of Proteolytic Immunity

Catalytic antibodies: balancing between Dr. Jekyll and Mr. Hyde

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