Pessanha, M, Morgado L, Louro RO, Londer YY, Pokkuluri PR, Schiffer M, Salgueiro CA.  2006.  Thermodynamic Characterization of Triheme Cytochrome PpcA from Geobacter sulfurreducens:? Evidence for a Role Played in e-/H+ Energy Transduction. Biochemistry. 45(46):13910-13917.