Effect of deuteration on the accuracy of HN-HN distance constraints.

The effect of deuteration on the measurement of HN-HN distances in moderately sized (15 kDa) proteins is discussed. Data are presented for a 15 kDa protein which is 95% deuterated on the Halpha position, and partially (70%) deuterated at other aliphatic sites. Deuteration of the protein increases the signal intensity of HN-HN cross peaks in NOESY spectra such that dipolar couplings between protons 4-5 A apart are readily detected. Experimental data and computer simulations show that either perdeuteration or partial deuteration of the protein increases the accuracy of amide-amide distance constraints. Thus, partial deuteration can be used to obtain more accurate long-range distance constraints for structure determination by NMR.