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bioRxiv · 10.1101/2024.09.26.615111

Engineered Nanobodies Bind Theranostic Main Group Metals

Ghosh, P.·Davies, L. J.·Nitsche, C.
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Abstract

Targeted theranostics heavily rely on metal isotopes conjugated to antibodies. Single-domain antibodies, known as nanobodies, are much smaller in size without compromising specificity and affinity. The conventional way of conjugating metals to nanobodies involves non-specific modification of amino acid residues with bifunctional chelating agents. We demonstrate that mutagenesis of a single residue in a nanobody creates a triple cysteine motif that selectively binds bismuth which is, for example, used in targeted alpha therapy. Two mutations create a quadruple cysteine mutant specific for gallium and indium used in positron emission tomography and single-photon emission computed tomography, respectively. Labelling is quantitative within a few minutes. The metal nanobodies maintain structural integrity and stability over weeks, resist competition from endogenous metal binders like glutathione, and retain functionality.

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Ghosh, P., Davies, L. J., Nitsche, C.. 2024-09-26. Engineered Nanobodies Bind Theranostic Main Group Metals. https://doi.org/10.1101/2024.09.26.615111

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