_EC 1.9.3.- With oxygen as acceptor. 85 PDB entries  
EC 1.-.-.- Oxidoreductases. [8,010 PDB entries]
EC 1.9.-.- Acting on a heme group of donors. [85 PDB entries]
EC 1.9.3.- With oxygen as acceptor. [85 PDB entries]    
EC 1.9.3.1 Cytochrome-c oxidase. [85 PDB entries]
EC 1.9.3.2 Transferred entry: 1.7.2.1. [-]

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