The objectives of this program are essentially in three parts: (1) development of methods for reversible attachment of peptides to solid supports under mild conditions by methods compatible with both aqueous and organic media; (2) adaptation of the attachment methods to solid supports compatible with both aqueous and organic media; and (3) exploration of the possibilities for enzymatic removal of protecting groups from amino acid and peptide derivatives. The ultimate aim of these separate efforts is the development of a system of solid phase peptide synthesis in which peptide chains can be elaborated in both the C- and N-terminal directions from the point of peptide-resin attachment with discretionary use of standard solid phase peptide synthetic techniques and new mild enzymatic methods. Final release of the completed peptide from the support must be achieved under very mild conditions.