The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Harald Kolmar - One of the best experts on this subject based on the ideXlab platform.
-
The Shark Strikes Twice: Hypervariable Loop 2 of Shark IgNAR Antibody Variable Domains and Its Potential to Function as an Autonomous Paratope
Marine Biotechnology, 2015Co-Authors: Stefan Zielonka, Martin Empting, Doreen Könning, Julius Grzeschik, Simon Krah, Stefan Becker, Stephan Dickgießer, Harald KolmarAbstract:In this present study, we engineered hypervariable loop 2 (HV2) of the IgNAR variable domain in a way that it solely facilitates antigen binding, potentially functioning as an autonomous Paratope. For this, the surface-exposed loop corresponding to HV2 was diversified and antigen-specific variable domain of IgNAR antibody (vNAR) molecules were isolated by library screening using yeast surface display (YSD) as platform technology. An epithelial cell adhesion molecule (EpCAM)-specific vNAR was used as starting material, and nine residues in HV2 were randomized. Target-specific clones comprising a new HV2-mediated Paratope were isolated against cluster of differentiation 3ε (CD3ε) and human Fcγ while retaining high affinity for EpCAM. Essentially, we demonstrate that a new Paratope comprising moderate affinities against a given target molecule can be engineered into the vNAR scaffold that acts independent of the original antigen-binding site, composed of complementarity-determining region 3 (CDR3) and CDR1.
-
the shark strikes twice hypervariable loop 2 of shark ignar antibody variable domains and its potential to function as an autonomous Paratope
Marine Biotechnology, 2015Co-Authors: Stefan Zielonka, Martin Empting, Doreen Könning, Julius Grzeschik, Simon Krah, Stefan Becker, Stephan Dickgieser, Harald KolmarAbstract:In this present study, we engineered hypervariable loop 2 (HV2) of the IgNAR variable domain in a way that it solely facilitates antigen binding, potentially functioning as an autonomous Paratope. For this, the surface-exposed loop corresponding to HV2 was diversified and antigen-specific variable domain of IgNAR antibody (vNAR) molecules were isolated by library screening using yeast surface display (YSD) as platform technology. An epithelial cell adhesion molecule (EpCAM)-specific vNAR was used as starting material, and nine residues in HV2 were randomized. Target-specific clones comprising a new HV2-mediated Paratope were isolated against cluster of differentiation 3e (CD3e) and human Fcγ while retaining high affinity for EpCAM. Essentially, we demonstrate that a new Paratope comprising moderate affinities against a given target molecule can be engineered into the vNAR scaffold that acts independent of the original antigen-binding site, composed of complementarity-determining region 3 (CDR3) and CDR1.
Juan R. De Los Toyos - One of the best experts on this subject based on the ideXlab platform.
-
a deeper analysis of the epitope Paratope of ply 5 a mouse monoclonal antibody which recognises the conserved undecapeptide tryptophan rich loop ectglawewwr of bacterial cholesterol dependent cytolysins
Biochemical and Biophysical Research Communications, 2013Co-Authors: Pedro Gonzalezmenendez, Marcos Garciaocana, Juan R. De Los ToyosAbstract:A previous study showed that the minimal epitope recognised by the PLY-5 mAb in the conserved undecapeptide Trp-rich loop of bacterial CDCs should consist of WEWWRT (Jacobs et al., 1999) [5]. Now, through immunoscreening of amino acid substitution analogues, it is concluded that the second Trp and the Arg residues are essential in the PLY-5 epitope. The E residue is an auxiliary epitope contributor. Antibody modelling and docking simulations provided support for these findings. For recognition by the antibody, the Trp-rich loop flipped out, mimicking the mechanism of membrane insertion. The displaced second Trp was seen to establish aromatic stacking interactions with aromatic residues of the antibody Paratope and the notably extruded guanidium tip of the arginine residue mediated electrostatic interactions with well-exposed carboxylic groups of glutamic residues on the surface of the Paratope. Thus, the epitope/Paratope interaction is mainly mediated by aromatic and by ionic interactions.
-
A deeper analysis of the epitope/Paratope of PLY-5, a mouse monoclonal antibody which recognises the conserved undecapeptide tryptophan-rich loop (ECTGLAWEWWR) of bacterial cholesterol-dependent cytolysins.
Biochemical and biophysical research communications, 2012Co-Authors: Pedro Gonzalez-menendez, Marcos García-ocaña, Juan R. De Los ToyosAbstract:A previous study showed that the minimal epitope recognised by the PLY-5 mAb in the conserved undecapeptide Trp-rich loop of bacterial CDCs should consist of WEWWRT (Jacobs et al., 1999) [5]. Now, through immunoscreening of amino acid substitution analogues, it is concluded that the second Trp and the Arg residues are essential in the PLY-5 epitope. The E residue is an auxiliary epitope contributor. Antibody modelling and docking simulations provided support for these findings. For recognition by the antibody, the Trp-rich loop flipped out, mimicking the mechanism of membrane insertion. The displaced second Trp was seen to establish aromatic stacking interactions with aromatic residues of the antibody Paratope and the notably extruded guanidium tip of the arginine residue mediated electrostatic interactions with well-exposed carboxylic groups of glutamic residues on the surface of the Paratope. Thus, the epitope/Paratope interaction is mainly mediated by aromatic and by ionic interactions.
Melvin Cohn - One of the best experts on this subject based on the ideXlab platform.
-
Dissecting the two models of TCR structure–function relationships
Immunologic Research, 2016Co-Authors: Melvin CohnAbstract:There are only two comprehensive models attempting to account for the TCR structure–function relationships, referred to as the Standard or Centric model (Model I) and the Tritope model (Model II). This essay is written to analyze comparatively the two formulations of restrictive reactivity, stressing in particular the logic of each. Model I is essentially built on an analogy between the TCR and the BCR. Given a TCR with only one combining site (Paratope), restrictive recognition requires that its ligand be viewed as a composite structure between the peptide and restricting element. It is this relationship that entrains a set of correlates that makes Model I untenable. Model II is predicated on the postulate that the recognition of the allele-specific determinants expressed by MHC-encoded restricting elements (R) is germline encoded and selected, whereas the recognition of peptide (P) is somatically encoded and selected. These selective pressures must operate on definable structures and this, in turn, necessitates a multiply recognitive T cell antigen receptor (TCR) with independent anti-R and anti-P Paratopes that function coherently to signal restrictive reactivity. The consequences of this “two repertoire” postulate give us a concept of TCR structure quite distinct from that at present generally accepted, as well as a surprising relationship between numbers of functional TCR V gene segments and allele-specific determinants in the species. In the end, both models must deal with the relationship between the epitope–Paratope interaction(s) and the signals to the T cell necessary for its differentiation and function.
-
An in depth analysis of the concept of “polyspecificity” assumed to characterize TCR/BCR recognition
Immunologic Research, 2008Co-Authors: Melvin CohnAbstract:A workshop group developed the concept of a “polyspecific” TCR/BCR in the framework of today’s consensus model. They argue that the individual TCR/BCR combining site is composed of a packet of specificities randomly plucked from the repertoire, hence it is “polyspecific.” This essay analyzes the conclusions of the workshop and suggests an alternative. “Polyspecificity” must be dissected into its two component parts, specificity and degeneracy. The TCR and the BCR must be treated differently because the TCR recognizes allele-specifically the MHC-encoded restricting element (R) that serves as the platform presenting peptide (P). Only the anti-P Paratope of the TCR behaves analogously to the BCR Paratope. The two Paratopes are selected to recognize a shape-determinant referred to as an epitope or ligand. The Paratope is functionally unispecific in recognition, not polyspecific, with respect to shape; it is degenerate in recognition with respect to chemistry. The recognized shape-determinant can be the product of many chemically different substances, peptide, carbohydrate, lipid, steroid, nucleic acid, etc. Such a degenerate set is functionally treated by the Paratope as one shape/epitope/ligand and, in no sense, can a Paratope recognizing such a degenerate set be described as “polyspecific.” Degeneracy and specificity are concepts that must be distinguished. The two positions are analyzed in this essay, the experiments used to support the view that the Paratope of the TCR/BCR is polyspecific, are reinterpreted, and an alternative framework with its accompanying nomenclature, is presented.
-
If the immune repertoire evolved to be large, random, and somatically generated, then...
Cellular immunology, 2002Co-Authors: R.e. Langman, Melvin CohnAbstract:The evolution of the somatically generated random combining site repertoire of the "adaptive" immune system depended on the concurrent appearance of a somatic process that sorted the repertoire into anti-self and anti-nonself. Unlike the germline-selected sorting process characteristic of "innate" defense mechanisms, somatic sorting of the repertoire requires that antigens be classified based on their behavior, not on their physical or chemical properties. As specific recognitive combining sites (Paratopes) define antigenic determinants (epitopes), the sorting of the repertoire operates epitope-by-epitope. By contrast, the coupling of the Paratope to effector function must operate antigen-by-antigen because the response to each epitope on the antigen must be in the same effector class (i.e., coherent). This distinction resolves a long standing debate and provides a basis for analyzing the various models.
-
Haplotype exclusion: the solution to a problem in natural selection.
Seminars in immunology, 2002Co-Authors: R.e. Langman, Melvin CohnAbstract:Antibody that possesses two identical Paratopes (bivalent) is aggregated by antigen to trigger effector function. Antibody that possesses two different Paratopes behaves as functionally monovalent. If these two antibodies interact with a given epitope, the monovalent antibody will block the aggregation of the bivalent antibody thereby inhibiting effector activation. We advance the hypothesis that haplotype exclusion is driven by the necessity to reduce the level of monovalent antibody. This assumption is compared to previous suggestions and quantitated. Further, several mechanisms of haplotype exclusion used by various species are analyzed in the light of this hypothesis.
Stefan Zielonka - One of the best experts on this subject based on the ideXlab platform.
-
The Shark Strikes Twice: Hypervariable Loop 2 of Shark IgNAR Antibody Variable Domains and Its Potential to Function as an Autonomous Paratope
Marine Biotechnology, 2015Co-Authors: Stefan Zielonka, Martin Empting, Doreen Könning, Julius Grzeschik, Simon Krah, Stefan Becker, Stephan Dickgießer, Harald KolmarAbstract:In this present study, we engineered hypervariable loop 2 (HV2) of the IgNAR variable domain in a way that it solely facilitates antigen binding, potentially functioning as an autonomous Paratope. For this, the surface-exposed loop corresponding to HV2 was diversified and antigen-specific variable domain of IgNAR antibody (vNAR) molecules were isolated by library screening using yeast surface display (YSD) as platform technology. An epithelial cell adhesion molecule (EpCAM)-specific vNAR was used as starting material, and nine residues in HV2 were randomized. Target-specific clones comprising a new HV2-mediated Paratope were isolated against cluster of differentiation 3ε (CD3ε) and human Fcγ while retaining high affinity for EpCAM. Essentially, we demonstrate that a new Paratope comprising moderate affinities against a given target molecule can be engineered into the vNAR scaffold that acts independent of the original antigen-binding site, composed of complementarity-determining region 3 (CDR3) and CDR1.
-
the shark strikes twice hypervariable loop 2 of shark ignar antibody variable domains and its potential to function as an autonomous Paratope
Marine Biotechnology, 2015Co-Authors: Stefan Zielonka, Martin Empting, Doreen Könning, Julius Grzeschik, Simon Krah, Stefan Becker, Stephan Dickgieser, Harald KolmarAbstract:In this present study, we engineered hypervariable loop 2 (HV2) of the IgNAR variable domain in a way that it solely facilitates antigen binding, potentially functioning as an autonomous Paratope. For this, the surface-exposed loop corresponding to HV2 was diversified and antigen-specific variable domain of IgNAR antibody (vNAR) molecules were isolated by library screening using yeast surface display (YSD) as platform technology. An epithelial cell adhesion molecule (EpCAM)-specific vNAR was used as starting material, and nine residues in HV2 were randomized. Target-specific clones comprising a new HV2-mediated Paratope were isolated against cluster of differentiation 3e (CD3e) and human Fcγ while retaining high affinity for EpCAM. Essentially, we demonstrate that a new Paratope comprising moderate affinities against a given target molecule can be engineered into the vNAR scaffold that acts independent of the original antigen-binding site, composed of complementarity-determining region 3 (CDR3) and CDR1.
Julius Grzeschik - One of the best experts on this subject based on the ideXlab platform.
-
The Shark Strikes Twice: Hypervariable Loop 2 of Shark IgNAR Antibody Variable Domains and Its Potential to Function as an Autonomous Paratope
Marine Biotechnology, 2015Co-Authors: Stefan Zielonka, Martin Empting, Doreen Könning, Julius Grzeschik, Simon Krah, Stefan Becker, Stephan Dickgießer, Harald KolmarAbstract:In this present study, we engineered hypervariable loop 2 (HV2) of the IgNAR variable domain in a way that it solely facilitates antigen binding, potentially functioning as an autonomous Paratope. For this, the surface-exposed loop corresponding to HV2 was diversified and antigen-specific variable domain of IgNAR antibody (vNAR) molecules were isolated by library screening using yeast surface display (YSD) as platform technology. An epithelial cell adhesion molecule (EpCAM)-specific vNAR was used as starting material, and nine residues in HV2 were randomized. Target-specific clones comprising a new HV2-mediated Paratope were isolated against cluster of differentiation 3ε (CD3ε) and human Fcγ while retaining high affinity for EpCAM. Essentially, we demonstrate that a new Paratope comprising moderate affinities against a given target molecule can be engineered into the vNAR scaffold that acts independent of the original antigen-binding site, composed of complementarity-determining region 3 (CDR3) and CDR1.
-
the shark strikes twice hypervariable loop 2 of shark ignar antibody variable domains and its potential to function as an autonomous Paratope
Marine Biotechnology, 2015Co-Authors: Stefan Zielonka, Martin Empting, Doreen Könning, Julius Grzeschik, Simon Krah, Stefan Becker, Stephan Dickgieser, Harald KolmarAbstract:In this present study, we engineered hypervariable loop 2 (HV2) of the IgNAR variable domain in a way that it solely facilitates antigen binding, potentially functioning as an autonomous Paratope. For this, the surface-exposed loop corresponding to HV2 was diversified and antigen-specific variable domain of IgNAR antibody (vNAR) molecules were isolated by library screening using yeast surface display (YSD) as platform technology. An epithelial cell adhesion molecule (EpCAM)-specific vNAR was used as starting material, and nine residues in HV2 were randomized. Target-specific clones comprising a new HV2-mediated Paratope were isolated against cluster of differentiation 3e (CD3e) and human Fcγ while retaining high affinity for EpCAM. Essentially, we demonstrate that a new Paratope comprising moderate affinities against a given target molecule can be engineered into the vNAR scaffold that acts independent of the original antigen-binding site, composed of complementarity-determining region 3 (CDR3) and CDR1.
