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Biomolecular NMR with 13C and 15N at natural abundance

Isotope labelling of protein, DNA and RNA samples is usually necessary for heteronuclear NMR. The reason for this is either the low sample concentration entailing low sensitivity or the intrinsically low sensitivity of some of the experiments which rely on magnetisation transfer over the ¹³C and ¹⁵N heteronuclei. The high sensitivity of cryogenically cooled probes, however, allows for experiments that formerly required full isotope labelling, on biomolecules containing one heteronucleus either at natural abundance or partially labelled.
 

Advantages:

• Working at natural abundance will reduce the overall cost as isotope-labelling may be expensive.
• Initial investigations can be undertaken with a singly ¹⁵N labelled protein.
• Isotope-labelling of DNA and RNA fragments can be avoided, though this is often difficult as it is done through synthesis. Natural abundance of ¹³C is preferred.