catalytic activity:Release of N-terminal amino acids, preferentially methionine, from peptides and arylamides.,cofactor:Binds 1 sodium ion per subunit. The sodium ion has a structural role.,cofactor:Binds 2 cobalt ions per subunit.,cofactor:Binds 2 cobalt ions per subunit. The true nature of the physiological cofactor is under debate. The enzyme is also active with zinc, manganese or divalent iron ions.,function:Removes the amino-terminal methionine from nascent proteins.,function:Removes the amino-terminal methionine from nascent proteins. Required for normal progression through the cell cycle.,similarity:Belongs to the peptidase M24A family.,