Structure elucidation of uniformly 13C labeled small molecule natural products.

Utilization of isotopically labeled proteins and peptides is a routinely employed approach in biomolecular NMR investigations. The widespread availability of inexpensive, uniformly (13) C-enriched glucose now makes it possible to produce uniformly (13) C-labeled natural products by microbial fermentation. In this feature article, the authors describe an experimental approach for the rapid structural characterization of uniformly (13) C-labeled natural products based on the Constant-Time HSQC (CT-HSQC) experiment. Rigorous theoretical evaluation of the CT-HSQC experiment allowed the applicability of the experiment to be expanded from the traditional, narrow scope of labeled amino acids to encompass virtually any small molecule or U-(13) C labeled natural product. A suite of experiments including CT-HSQC, (13) C-(13) C COSY, and COSYLR experiments is sufficient for the structure elucidation of uniformly (13) C-labeled small molecules and natural products. Differences in NMR approaches for structure elucidation of natural abundance and uniformly (13) C-labeled molecules are also discussed. The present work provides a researcher working in this area of natural products chemistry with NMR structure elucidation tools for investigating (13) C-labeled small molecules and natural products.