Abstract: The invention relates to cathepsin O proteins, nucleic acids, and antibodies.

Abstract: Method and apparatus for simple and rapid preparation of reusable, addressable surface-immobilized arrays of biomolecules (libraries) used for screening for interaction with any biologically significant target. A special plate having on its surface a plurality of discreet functionalized substrate areas, typically in arrays of 10.times.10 to 400.times.400, is provided for chemical synthesis or bonding thereon of desired families of biomolecules (e.g. peptides, DNA, RNA, oligosaccharides). In the case of peptides, such as hexapeptides, the resulting permanently hexapeptide-loaded plate is a reusable Addressable Synthetic Peptide Combinatorial Library (ASPCL), in which 1 to 3 (typically two) of the positions in the sequence are uniquely identified by the address location. Plate embodiments include substrates of physically bonded (e.g.