6x(13)C labeled residue 6x(13)C labeled L-isoleucine (12)C -6 (13)C 6 (13)C 6 H 11 N 1 O 1 119.09999847412109375 119.10419464111328125 13C(6) Silac label 6.0199999809265136719 6.0201292037963867188 A protein modification that effectively converts an L-isoleucine residue to 6x(13)C labeled L-isoleucine. I Label:13C(6) MOD:01333 PSI-MOD Unimod:188 artifact