The MDB is part of a program project that focuses on understanding the metalloproteins structurally and functionally, to the level that we can do rational design and construction of new metalloproteins. The program project is (was) *The Metalloprotein Bioinformatics, Structure, and Design Program* at TSRI. To accomplish our objectives we need to: Understand the geometrical requirements to bind a metal Figure out the effect of the environmental constrains Devise methods to design the sites Analyze the possible candidates Make the sites Find out where we suceeded and where we failed Go back to step 1 Thus, building a quantitative database was critical.