_EC 3.1.31.- Endoribonucleases active with either ribo- or deoxyribonucleic ac 237 PDB entries  
EC 3.-.-.- Hydrolases. [22,079 PDB entries]
EC 3.1.-.- Acting on ester bonds. [6,228 PDB entries]
EC 3.1.31.- Endoribonucleases active with either ribo- or deoxyribonucleic ac [237 PDB entries]    
EC 3.1.31.1 Micrococcal nuclease. [237 PDB entries]