Application of proteins and peptides as human therapeutics is developing rapidly with the discovery of novel peptides and proteins . 1,2 Many peptide derived molecules can be destroyed in the digestive system and in the circulatory system, removed by proteolytic digestion and rapid renal excretion. 3 Covalent attachment of synthetic macromolecules is an effective way to improve protein stability with reduced immunogenicity and extended plasma half-lives. 4–11 ...
