Empirical 3JHN-CO values and angular backbone constraints can be interconverted following well-known Karplus relationships: 95JACS1810 ,.VALUES
3JHN-CO=4.02*cos2(fi) - 1.12*cos(fi) + 0.07 ( 96JACS2483 ) 3JHN-CO=4.41*cos2(fi) - 1.36*cos(fi) + 0.24 ( 99JB1-14 ) where fi is the backbone torsion angle.
The expected 3JHN-CO coupling constant values found in secondary structure elements of proteins:MEASUREMENT
- Alpha-helix: 1.4 Hz
- 310-helix: 1.3 Hz
- Beta-strand: 0.9 Hz
Several methods have been proposed to measure 3JHN-CO coupling constants:RELATED TOPICS
- 3D heteronuclear relayed E.COSY experiment combined with 2D multiplet line-shape analysis ( 95JB95 and 96JB142 ).
- 3D CO-coupled (H)CANNH experiment ( 95JB25 ).
- The CO-FIDS method: 95JB237 .
- 3D HN(CA)CO-J experiments 94JMRB172-104 .
- 3D HNCA[CO]-E.COSY experiment.
- 3D HCN experiment for perdeuterated proteins ( 03JACS44 )
The same dihedral angle information can be obtained from other coupling constants values:
