A construct is provided that is capable of binding a plurality of molecules, the construct comprising a first moiety with a first molecule binding region and a first molecule non-binding region; and a second moiety with a second molecule-binding region and a second molecule-non-binding region, whereby the first binding region and second binding region are at opposite ends of the construct. Also provided is a method for detecting protein having certain amino acid sequences, the method comprising supplying a collection of proteins each with unknown amino acid sequences, contacting the collection with a moiety having a plurality of binding sites capable of binding with the protein having certain amino acid sequences so as to form a moiety-protein complex, and mixing the complex with a marker specific for the moiety in an amount sufficient to indicate existence of the complex.