Characterization of the linker peptide of the single‐chain Fv fragment of an antibody by NMR spectroscopy

Abstract

A comparison of the single-chain F_v fragment of the antibody McPC603 (scF_v) with its corresponding unlinked F_v. fragment has been carried out with ¹⁵N-edited NMR spectroscopy. The two F_v, fragments adopt the same structure, indicating that the linker does not perturb the folding of the domains. This also directly demonstrates that folding in vivo (F_v fragment) and in vitro (scF_v. fragment) leads to the same structure. The main differences in the spectra of the uniformly ¹⁵N-labeled scF_v and F_v fragments are due to signals of Gly and Ser from the linker peptide of the scF _v , fragment. The linker peptide has been mapped with NMR spectra of ¹⁵N-glycine- and ¹⁵N-glycine¹⁵N-serine-labeled scF_vfragments. The ¹⁵N T₂, relaxation data indicate that the linker peptide is more flexible than the rest of the molecule.