Metal ion-binding [mp] refers to proteins that bind positive metal ions as substrates, cofactors, etc. HotPatch's statistical parameters for metal ion-binding are derived by training on a set of structures in this class.

In training on their known functional sites, the sites were defined by:

• Annotations as binding residues in the SFR Database, which were mostly obtained from the literarture.
• Proximity of 4Å to a positive metal ion (if present in the structure), or to a known surrogate of the normal metal (e.g. zinc known to bind where iron normally does).

Size of training set: 165 structures (152 with hydrogens added, for electrostatics & neural networks).