Chiral β and random fractional deuteration for the determination of protein sidechain conformation by NMR

Stereospecific assignments of the aspartic acid and asparagine, β‐protons of the 108 residue protein E. coli thioredoxin have been obtained by the use of chiral deuteration. In addition protein samples have been prepared in which all carbon bound hydrogen positions are substituted to an extent of 75% with deuterium. These random fractionally deuterated samples significantly facilitate the measurement of coupling constants and intraresidue NOE intensities which combined with the stereospecific assignments have provided determination of the first sidechain dihedral angle ϰ 1 , for all four asparagine residues and eight of the ten assigned aspartic acid residues.