obsolete formation of peptidyl-cystine persulfide by sulphur transfer from free cysteine (obsolete GO:0044526)
OBSOLETE. The modification of a peptidyl-cystine residue in a protein by the transfer of a sulfur atom from a free cysteine (in the process converting the free cysteine to alanine) to the peptidyl-cysteine to form peptidyl-cysteine persulfide.