Non-ribosomal peptide synthetases (NRPSs) are macromolecular enzymatic complexes responsible for the biosynthesis of an array of microbial natural products, many of which have important applications for human health. The nature of the NRPS machinery, which has been likened to an assembly line, should be amenable to bio-engineering efforts directed towards efficient synthesis of novel and tailored molecules. However, the success of such endeavours depends on a detailed understanding of the mechanistic principles governing the various steps in the peptide assembly-line. Here, we report the near-complete assignment of the Ile, Met, Leu and Val methyl-groups of the 59-kDa adaptor-condensation di-domain (BN-BC) from the Tomaymycin NRPS. These assignments will provide the foundation for future NMR studies of the complex dynamic behaviour of the condensation domain both in isolation and in the context of the enzymatic cycle, which will themselves form the basis for developing a complete mechanistic description of the central condensation reaction in this prototypical NRPS.