Presence and Location of an Unusual Amino Acid, ε-N-Trimethyllysine, in Cytochrome c of Wheat Germ and Neurospora

Wheat germ cytochrome c contains 2 residues of e-Ntrimethyllysine (lysine betaine) at positions 72 and 86.Neurospora cytochrome c possesses this lysine derivative at Residue 72.No trace of c-N-methyl-or e-N-dimethyllysine was found in these proteins.Residue 72 is present in the sequence comprising Residues 70 through 80 which is invariant in all cytochromes of this type and Residue 86 is present in a region which is characterized in almost all cytochromes as being either Lys-Lys or Lys-Lys-Lys.Some possible implications of these findings with respect to the interaction of cytochrome c with cytochrome oxidase are discussed.During