The Trustees of Columbia University received US Patent No. 6,743,630, “Method of preparing a protein array based on biochemical protein-protein interaction.” The patent covers a method of preparing a protein array based on biochemical protein-protein interactions. The array begins with a first protein, which includes a PDZ domain, deposited on a substrate. A second protein is applied to the array and bound to the PDZ domain of the first protein. This protein includes a specific amino acid sequence described thusly: (S/T)—X—(V/I/L)-COOH.