tokens: A comparison of the amino acid sequence of the T . thermophilus enzyme with that of the Escherichia coli enzyme showed ( i ) a 37 % overall similarity ; ( ii ) the conservation of the Ser residue , which is known to be phosphorylated in the E . coli enzyme , and of the surrounding sequence ; and ( iii ) the presence of 141 extra residues at the C terminus of the T . thermophilus enzyme .