A method for protecting a peptide from peptidase activity in vivo, the peptide
being composed of between 2 and 50 amino acids and having a C-terminus and an N-terminus
and a C-terminus amino acid and an N-terminus amino acid is described. In the first
step of the method, the peptide is modified by attaching a reactive group to the
C-terminus amino acid, to the N-terminus amino acid, or to an amino acid located
between the N-terminus and the C-terminus, such that the modified peptide is capable
of forming a covalent bond in vivo with a reactive functionality on a blood component.
In the next step, a covalent bond is formed between the reactive group and a reactive
functionality on a blood component to form a peptide-blood component conjugate,
thereby protecting said peptide from peptidase activity. The final step of the
method involves the analyzing of the stability of the peptide-blood component conjugate
to assess the protection of the peptide from peptidase activity.
