Extended Data Fig. 6: Activity of Mmp10 on peptide substrate.

a, Influence of the critical R285 residue. Reactions were analyzed by LC-MS. Only for the wild-type peptide a methyl transfer reaction was observed (mass shift of Δm= +14 Da). See Extended Data Table 2 for peptide masses and Extended methods for reaction conditions. b, Activity of Mmp10 incubated with the wild-type peptide alone (left panel) or the wild-type and citrulline-containing peptides (right panel). Reactions were analyzed by LC-MS. Methylated peptide [M+H] ⁺= 1510.79 (circles), 5′-dA [M+H] ⁺= 252.11 (squares) and SAH [M+H] ⁺= 385.13 (triangles). Experiments were performed in duplicate. c, Formation of MeCbl by Mmp10 in the absence or the presence of Ti(III)citrate. Mmp10 was incubated under anaerobic and reducing conditions with SAM (1 mM), OHCbl (100 µM) and DTT (6 mM). Diamonds: Reaction with 1mM Ti(III)citrate. Squares: Reaction without Ti(III)citrate. Circles: Control reaction without enzyme and Ti(III)citrate. Experiments were performed in duplicate. MeCbl was detected by LC-MS analysis [M+H]²⁺: 672.80 and comparison with its retention time with authentic standard.