Abstract: The present invention generally pertains to methods of identifying sequence variants in a protein of interest. In particular, the present invention pertains to the use of heavy peptide standards with liquid chromatography-mass spectrometry analysis to specifically identify sequence variants of a protein of interest.

Abstract: The present invention generally pertains to methods of characterizing peptides or proteins of interest. In particular, the present invention pertains to the use of the nonionic surfactant DDM to improve recovery of hydrophobic peptides in pharmacokinetic, reduced peptide mapping, or other biotherapeutic protein analyses.

Abstract: Methods for characterizing host-cell proteins in a sample matrix are provided.

Abstract: The present invention generally pertains to methods of preventing disulfide scrambling in non-reducing liquid chromatography-mass spectrometry analysis of a protein of interest. In particular, the present invention pertains to the addition of cystamine to a non-reducing liquid chromatography-mass spectrometry analysis of an antibody to prevent disulfide scrambling.

Abstract: The present disclosure provides an improved method for accurately measuring the amino acid sequence of a therapeutic protein, in particular, an antibody, to insure the homogeneity of the protein such that it is suitable for administering to a human subject for treating a disease or disorder. The methods employ analytical physical chemistry techniques, in particular, a guided electron-transfer dissociation (ETD) and mass spectrometry (MS) approach for robust sequence coverage of the molecule with high accuracy and speed of use.

Abstract: The present disclosure provides an improved method for profiling the nature of undesirable host cell proteins (HCPs) in a therapeutic antibody preparation using an improved assay. The assay includes three (3) exemplary steps comprising: ultra-low trypsin digestion, long gradient liquid chromatography, and mass spectrometry (MS) using, in particular, BoxCar mass spectrometry. The disclosure allows for determining the purity of a therapeutic antibody such that it is suitable for use in patients.

Abstract: The present disclosure provides a method for measuring post-translational modifications in proteins such as antibodies. In particular, the method may be used to quantify C-terminal truncation in antibodies that incorporates heavy isotopic standards for both the unprocessed C-terminal K peptide and the truncated C-terminal K peptide to build a calibration curve and quantify this PTM using mass spectrometry. Quantification of post-translational modifications may occur in a single liquid chromatography tandem mass spectrometry (LC-MS2) run.

Abstract: The present disclosure provides a method for accurately measuring post-translational modifications in proteins such as antibodies. In particular, the method pertains to the use of heavy isotopic standards to generate a calibration curve to allow for accurate quantitation of a modified peptide. The method may be used to accurately quantify C-terminal truncation in antibodies using mass spectrometry.

Abstract: Methods for characterizing host-cell proteins in a sample matrix are provided.

Abstract: Compositions and methods of tagging peptides and other molecules using novel isobaric tandem mass tagging reagents, including novel N, N-dimethylated amino acid 8-plex and 16-plex isobaric tandem mass tagging reagents. The tagging reagents comprise: a) a reporter group having at least one atom that is optionally isotopically labeled; b) a balancing group, also having at least one atom that is optionally isotopically labeled, and c) an amine reactive group. The tagging reagents disclosed herein serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency.

Abstract: Compositions and methods of tagging peptides and other molecules using novel isobaric tandem mass tagging reagents, including novel N, N-dimethylated amino acid 8-plex and 16-plex isobaric tandem mass tagging reagents. The tagging reagents comprise: a) a reporter group having at least one atom that is optionally isotopically labeled; b) a balancing group, also having at least one atom that is optionally isotopically labeled, and c) an amine reactive group. The tagging reagents disclosed herein serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency.

Abstract: Compositions and methods of tagging peptides and other molecules using novel isobaric tandem mass tagging reagents, including novel N,N-dimethylated amino acid 8-plex and 16-plex isobaric tandem mass tagging reagents. The tagging reagents comprise: a) a reporter group having at least one atom that is optionally isotopically labeled; b) a balancing group, also having at least one atom that is optionally isotopically labeled, and c) an amine reactive group. The tagging reagents disclosed herein serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency.

Abstract: Compositions and methods of tagging peptides and other molecules using novel isobaric tandem mass tagging reagents, including novel N,N-dimethylated amino acid 8-plex and 16-plex isobaric tandem mass tagging reagents. The tagging reagents comprise: a) a reporter group having at least one atom that is optionally isotopically labeled; b) a balancing group, also having at least one atom that is optionally isotopically labeled, and c) an amine reactive group. The tagging reagents disclosed herein serve as attractive alternatives for isobaric tag for relative and absolute quantitation (iTRAQ) and tandem mass tags (TMTs) due to their synthetic simplicity, labeling efficiency and improved fragmentation efficiency.