The TROSY principle has been introduced into a HNCA experiment, which is designed for measurements of the intraresidual and sequential Hα-Cα/HN-N dipole/dipole and Hα-Cα/N dipole/CSA cross-correlated relaxation rates. In addition, the new experiment provides values of the 3,4 J Hα HN coupling constants measured in an E.COSY manner. The conformational restraints for the ψ and φ angles are obtained through the use of the cross-correlated relaxation rates together with the Karplus-type dependencies of the coupling constants. Improved signal-to-noise is achieved through preservation of all coherence transfer pathways and application of the TROSY principle. The application of the [15N,13C]-DQ/ZQ-[15N,1H]-TROSY-E.COSY experiment to the 16 kDa apo-form of the E. coli Heme Chaperon protein CcmE is described. Overall good agreement is achieved between ψ and φ angles measured with the new experiment and the average values determined from an ensemble of 20 NMR conformers.