Specifies a dynamic mass adjustment to be applied to protein C-terminal amino acids during spectral analysis. Peptides containing the protein C-termnius are tested with and without the dynamic modification mass. The relative mass difference can be any non-zero value. If multiple dynamic protein C-terminal modification masses are desired, use multiple modification_protC declarations.
NOTE: When the mass value of modification_protC is zero, the parameter is ignored. Some configuration files may have the value set to zero, simply to have a modification_protC placeholder in the file.
1.5.4 - present
To indicate possible labeling of protein C-terminus: modification_protC = 56.037448