_EC 1.12.-.- Acting on hydrogen as donors. 251 PDB entries  
EC 1.-.-.- Oxidoreductases. [21,435 PDB entries]
EC 1.12.-.- Acting on hydrogen as donors. [251 PDB entries]
EC 1.12.1.- With NAD(+) or NADP(+) as acceptor. [18 PDB entries]
EC 1.12.2.- With a cytochrome as acceptor. [69 PDB entries]
EC 1.12.5.- With a quinone or similar compound as acceptor. [-]
EC 1.12.7.- With an iron-sulfur protein as acceptor. [54 PDB entries]
EC 1.12.98.- With other, known, acceptors. [30 PDB entries]
EC 1.12.99.- With other acceptors. [80 PDB entries]

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