Fig 4.

Alignment of the sequences for Cpb from Clostridium perfringens and Cab from Methanothermobacter thermautotrophicus. The deduced sequences were aligned by using ClustalX (50). Abbreviations and gene identification numbers: C.p., C. perfringens, gi|110799007; M.t., M. thermautotrophicus, gi|1272331. The numbering corresponds to the M. thermautotrophicus sequence. Residues 32, 87, and 90 are ligands to zinc. Residues 34 and 36 are the Asp/Arg pair important for the proton transfer step of catalysis.