Patent ID: 9063149
Filing Date: 2015-06-23
Classification: C07B,C07K,G01N

Abstract:
1. A method of determining the absolute amount of a target polypeptide in a sample, said method comprising the following steps: (a) adding to said sample, wherein said fusion polypeptide is mass-altered as compared to said target polypeptide and said tag polypeptide, said mass-alteration resulting from isotope labeling or isobaric tagging; (b) performing proteolytic digestion of the mixture obtained in step (a); (c) subjecting the result of proteolytic digestion of step (b), optionally after chromatography, to mass spectrometric analysis; and (d) determining the absolute amount of said target polypeptide from (i) the peak intensities in the mass spectrum acquired in step (c) of said fusion polypeptide, said tag polypeptide and said target polypeptide and (ii) said known absolute amount of said tag polypeptide.