_EC 1.2.2.- With a cytochrome as acceptor. 0 PDB entries  
EC 1.-.-.- Oxidoreductases. [8,574 PDB entries]
EC 1.2.-.- Acting on the aldehyde or oxo group of donors. [496 PDB entries]
EC 1.2.2.- With a cytochrome as acceptor. [-]    
EC 1.2.2.1 Formate dehydrogenase (cytochrome). [-]
EC 1.2.2.2 Deleted entry. [-]
EC 1.2.2.3 Formate dehydrogenase (cytochrome c-553). [-]
EC 1.2.2.4 Carbon-monoxide dehydrogenase (cytochrome b-561). [-]

[-] signifies that there are no PDB entries for the given enzyme subclass