Patent ID: 7598222

Claim:
A method of preparing Val 8 -GLP-1(7-37)OH [SEQ ID NO:15] that is soluble in aqueous solution at physiological pH, said Val 8 -GLP-1(7-37)OH being referred to as “soluble Val 8 -GLP-1(7-37)OH”, from Val 8 -GLP-1(7-37)OH that is insoluble in aqueous solution at physiological pH, said Val 8 -GLP-1(7-37)OH being referred to as an “insoluble Val 8 -GLP-1(7-37)OH”, said method comprising the steps of: a) dissolving insoluble Val 8 -GLP-1(7-37)OH in aqueous base having a pH between about 12.1 to about 12.5 to form a Val 8 -GLP-1(7-37)OH solution; b) pH-adjusting the Val 8 -GLP-1(7-37)OH solution within about thirty minutes after dissolution of Val 8 -GLP-1(7-37)OH to a pH at which substantially no amino acid racemization of the dissolved Val 8-GLP-1(7-37)OH occurs, wherein the pH is between about 7.0 to about 8.5; c) filtering the pH-adjusted solution of step b) through a filter membrane having a porosity of between about 0.20 μm to about 0.25 μm; and d) isolating soluble Val 8 -GLP-1(7-37)OH from the filtered solution of step c).