Abstract: Methods and compositions are provided for identifying compounds having affinity or complementarity to a target molecule. Compounds according to the invention may be described by the formula E-Ca—R—Cb-A, wherein E is a therapeutic or diagnostic agent, R is a reactive group, Ca and Cb are connector groups between E and R and between R and A, respectively, and A is an affinity group comprising the sequence F-1-Y-E-E. Compounds according to the invention may be used for labeling the target molecule, particularly where the target molecule is naturally found in a complex mixture, such as a physiological fluid, like blood. By affinity labeling in vivo, the lifetime of physiologically active entities can be greatly enhanced by becoming bound to long-lived blood components. The covalently bound entity may also serve as an antagonist or agonist of a particular binding protein or as an enzyme inhibitor.

Abstract: Methods and compositions are provided for identifying compounds having affinity to a target site. The method provides for the affinity group to be a leaving group from a reactive functionality capable of forming a covalent bond to the target site. One can combine the compound comprising the target site with the library, and assay for the resulting composition of the leaving groups. The leaving groups having the highest concentration can be identified as the groups having the binding highest affinity for the target site. The selected compounds may then be used for labeling the target molecule, particularly where the target molecule is naturally found in a complex mixture, such as a physiological fluid, like blood. By affinity labeling in vivo, the lifetime of physiologically active entities can be greatly enhanced by becoming bound to long lived blood components. The covalently bound entity may also serve as an antagonist or agonist of a particular binding proteins or as an enzyme inhibitor.

Abstract: Novel methods and compositions are provided for preferentially bonding an oligomeric molecule to a macromolecular target where the target is a member of a complex mixture and/or there is preferential bonding at one of a plurality of available bonding sites of the macromolecular target. The methods represent a complete system for both producing and identifying affinity label molecules from a combinatorial library which preferentially bind to a marcomolecular target or target site and preferentially binding those affinity labels to a macromolecule of interest either ex vivo or in vivo. Macromolecular targets include a variety of cellular- and non-cellular-associated proteins.