Uniform labeling of a recombinant antibody Fv-fragment with 15N and 13C for heteronuclear NMR spectroscopy.

The expression of functional antibody fragments in Escherichia coli enables a detailed analysis by NMR spectroscopy. This is demonstrated with the uniform labeling of an Fv-fragment (25 kDa) comprising the antigen binding site of an antibody against 2-phenyloxazolone with 15N and 13C. The antigen-complexed Fv-fragment was analysed for a potential assignment by heteronuclear multi-dimensional NMR spectroscopy. For almost all backbone amides 15N/1H crosspeaks and for 80% of them TOCSY crosspeaks were observed. In a 13C-edited-HCCH-2D experiment 17 out of 18 threonine spin-systems were identified. Thus detailed assignments are possible, but some amino acid specific labeling in addition to uniform labeling will be required for complete assignments of Fv-fragments.