Kirley TL, Norman AB. Ligand binding to a humanized anti-cocaine mAb detected by non-reducing SDS-PAGE.
Biochem Biophys Rep 2020;
23:100795. [PMID:
32817883 PMCID:
PMC7424207 DOI:
10.1016/j.bbrep.2020.100795]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/31/2020] [Indexed: 12/17/2022] Open
Abstract
Monoclonal antibodies are very useful tools in experimental biology, as well as being valuable and effective therapeutic drugs. They can be targeted against proteins with varied functions, or against small molecules of interest to both researchers and clinicians, such as drugs of abuse, including cocaine. Since there is no currently FDA approved pharmacological treatment for cocaine abuse, our laboratory has developed an anti-cocaine mAb for the treatment of cocaine use disorders. This humanized anti-cocaine antibody, named h2E2, has been thoroughly characterized both functionally and structurally, in preparation for the start of clinical development. We previously showed that this mAb could be characterized by sequential thermal unfolding of antibody domains using non-reducing SDS-PAGE. We also demonstrated that ligand-induced protein stabilization can be used to quantitatively measure cocaine and cocaine metabolite binding to the h2E2 mAb, utilizing differential scanning fluorimetry. Here, we demonstrate the utility of non-reducing SDS-PAGE for the qualitative assessment of binding of cocaine and some of its metabolites, both to the intact mAb, as well as to fragments containing the antigen binding site (Fab and F(ab’)2 fragments). These results clearly show a ligand concentration dependence of the stabilization of the cocaine binding domain in non-reducing SDS-PAGE, as well as visually differentiating the relative binding affinities of various cocaine metabolites. Thus, non-reducing SDS-PAGE is a simple and widely available technique that is useful as a measure of binding of cocaine and its metabolites to the h2E2 mAb, and it is likely that this technique will also be applicable to other small molecule-directed mAbs.
Cocaine and metabolite mAb binding are visually assessed by non-reducing SDS-PAGE.
Ligand-induced changes are observed with the intact mAb, F(ab’)2, and Fab fragments.
No ligand-induced changes in gel bands are observed for the Fc mAb fragment.
The ligand-induced differential banding patterns are ligand concentration dependent.
High affinity cocaine metabolites cause the effect, low affinity metabolites do not.
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