ABSTRACT
Cytochromes c (cyts c) are small monomeric proteins of 80-120 residues involved in different and crucial aspects of cellular life, from electron-transport processes to apoptosis. These heme-proteins show a typical α-helical fold that is recognized as a structural superfamily in protein classification tools such as SCOP (Andreeva et al. 2008) or CATH (Orengo et al. 1997). The three major α-helices (generally referred to as N-terminal helix, 60s helix, and C-terminal helix, following numbering of amino acidic residues of horse heart cyt c) wrap around the heme group that is covalently linked to the protein via two thioether bonds between its vinyl groups and two cysteine residues in the conserved CysXaaXaaCysHis motif (Figure 2.1).
