Improved measurement of 13C, 31P J coupling constants in isotopically labeled RNA.

3JCP coupling constants have been measured in a 99% 13C,15N labeled lead-dependent ribozyme, known as the leadzyme. These coupling constants were determined by analysis of the intensity of individual crosspeaks in a spin-echo difference constant time HSQC experiment. This procedure permits improved measurement of the 3JC2'P and 3JC4'P coupling constants in isotopically labeled RNA and yielded valuable information on the beta and epsilon backbone torsion angles in the leadzyme.