n - and c - terminal peptide selection method for proteomics

摘要

Reducing (M1) the complexity of a proteomic sample, and preferably identifying proteins in the sample, comprises protecting the protein N- or C-termini with a suitable protecting agent, cleaving the protected proteins, separating the protected peptides from the peptide mixture, to reduce the sample complexity to one terminal peptide per sample protein, and, optionally, detecting the terminally protected peptides. Reducing (M1) the complexity of a proteomic sample, and preferably identifying proteins in the sample, comprises: (a) providing one or more proteins; (b) protecting the protein N- or C-termini with a suitable protecting agent; (c) cleaving the terminally protected proteins with a suitable cleaving agent to produce a mixture of terminally protected peptides and non-terminally protected peptides comprising free amino and carboxyl groups corresponding to the cleavage sites; (d) separating the terminally protected peptides from the peptide mixture, to reduce the sample complexity to one terminal peptide per sample protein; and, optionally (e) detecting the terminally protected peptides. Independent claims are also included for: (1) quantitatively comparing (M2) protein levels in two or more proteomic samples, comprising: (a) providing two or more samples each containing one or more proteins; (b) carrying out steps (b)-(d) of (M1), for each sample, thus reducing the sample complexity for each of the two or more protein samples to one terminal peptide per sample protein; (c) differentially labeling the terminally protected peptides of each sample with a suitable reagent comprising a detectable label, to generate two or more sets of differentially labeled terminal peptides; (d) measuring the relative levels of the differentially labeled terminal peptides, having optionally first combined the sets of labeled peptides; (2) a kit (II) for identifying proteins in a proteomic sample comprising one or more protecting agents for protecting the N- or C-termini, one or more cleaving agents, and means for separating the N- or C-terminally protected peptides from the mixture; and (3) a proteomic sample of reduced complexity obtainable by (M1).