Patent ID: 9580471
Date: 2017-02-28
CPC Classifications: C07K

Claim:
1. A process of preparing a peptide consisting of the GCC agonist sequence of SEQ ID NO: 1, wherein the GCC agonist sequence is n amino acid units in length, with the N-terminal unit at position 1 and the C-terminal unit at position n, the process comprising: providing a first fragment having a first sequence of amino acid units from position j through position k of the GCC agonist sequence, wherein j is an integer between 1 and n−1, k is an integer between 2 and n and is greater than j, and the first fragment is protected except for an amino group of the amino acid unit at position j, or alternatively, a carboxyl group of the amino acid unit at position k, providing a second fragment having a second sequence of amino acid units from position h through position j−1 of the GCC agonist sequence or having a third sequence of amino acid units from position k+1 through position m of the GCC agonist sequence, wherein h is an integer between 1 and n−2 and is smaller than j, m is an integer between k+2 and n, and the second fragment is protected except for a carboxyl group of the amino acid unit at position j−1 or an amino group of the amino acid unit at position k+1, wherein at least one of the first and second fragments is provided via a solid-phase peptide synthesis; and coupling the first and the second fragments via a solution-phase synthesis to yield a protected peptide having a sequence of amino acid units from position h through position k of the GCC agonist sequence or a protected peptide having a sequence of amino acid units from position j through position m of the GCC agonist sequence, and wherein the peptide is purified by a process comprising adsorbing the peptide onto a polymeric adsorbent column, optionally rinsing the peptide with deionized water, eluting the optionally rinsed peptide off the polymeric adsorbent column with an isopropanol aqueous solution to form a peptide solution, removing water and the isopropanol from the peptide solution to precipitate the peptide, and optionally adding an ether to the dewatered peptide to facilitate precipitation of the peptide.