modified L-histidine residue L-histidine removal -137.0589141845703125 -137.1399993896484375 A protein modification that effectively removes or replaces an L-histidine. C -6 H -7 N -3 O -1 H MOD:01639 PSI-MOD This represents the loss or replacement of an L-histidine residue in a polypeptide, and may be combined with the formula or mass of another entry that is the replacement residue to represent a mutation or substitution. natural natural, standard, encoded residue removal