Figure 5: Sketch of the chain-fold of CCD enzyme showing the seven-bladed β-sheet as the basic motif. Distinct types of β-sheets were presented by colored arrowheads. Bottle green boxes stand for α-helix. (a) The second structure of CCD7 enzyme from Prochlorococcus MIT9312 (PMT9312_0282), (b) CCD7 from Nostoc punctiforme ATCC 29133 (Npun_F0298), (c) APCO from Cyanothece sp. PCC 7424 (PCC7424_5321), (d) CCD1 from Anabaena sp. PCC 7120 (all1106).