US 2026/0056205 A1 · METHOD TO DISTINGUISH ASPARTATE FROM ISOASPARTATE IN A PROTEIN

Abstract

Methods and compositions for detecting isoaspartate residues in polypeptides using mass spectrometry, and for distinguishing isoaspartate residues from aspartate and/or asparagine residues in a polypeptide using MS analysis. Polypeptides containing one or more isoaspartate residues, or suspected of containing one or more isoaspartate residues, are treated with L-isoaspartyl methyltransferase (PIMT), which is able to selectively modify isoaspartate and impart a mass change to the amino acid residue. The polypeptide is then analysed using mass spectrometry, where a mass change caused by the PIMT reaction is detected and characterized. Preferably, these methods are able to be performed without the use of liquid chromatography or other similar separation techniques prior to mass spectrometry analysis.

Claims20

Dependent claims

A method of analyzing a first polypeptide having one or more amino acid residues of isoaspartate, aspartate, asparagine, or any combination thereof, wherein each isoaspartate residue has a first mass;

the method comprising the steps of:
a) contacting the first polypeptide with a composition comprising protein L-isoaspartyl methyltransferase (PIMT), wherein the PIMT selectively modifies one or more isoaspartate residues, and generating a modified polypeptide comprising one or more modified isoaspartate residues, wherein each of the one or more modified isoaspartate residues has a different mass than the first mass;
b) analyzing the modified polypeptide using a mass spectrometer device, and obtaining mass spectrometry data on the modified polypeptide, wherein the mass spectrometry data comprises a mass-to-charge ratio of the modified polypeptide and/or one or more fragment ions thereof;
c) characterizing the presence and/or amount of modified isoaspartate residues in the modified polypeptide based on the mass spectrometry data.

1 more element

Dependencies are inferred from the claim text.

Method to distinguish aspartate from isoaspartate in a protein

Life of this patent

Method to distinguish aspartate from isoaspartate in a protein

Life of this patent

Abstract

Claims20