title: Chemoenzymatic labeling of protein C-termini for positive selection of C-terminal peptides.
abstract: Many proteomic experiments require selective labeling of either N- or C-termini of proteins and recovery of terminal peptides. Although N-termini can be selectively labeled, selective labeling of protein C-termini has not been possible due to the difficulty in discriminating between the carboxyl group on the C-terminus versus that on aspartate and glutamate residues. Here we describe the first simple proteomic approach for positive selection of protein C-termini, Profiling Protein C-Termini by Enzymatic Labeling (ProC-TEL). ProC-TEL uses carboxypeptidase Y and other readily available reagents to selectively add an affinity tag to protein C-termini and to capture C-terminal peptides from complex cell lysates for mass spectrometry (MS) identification. Using ProC-TEL, we identify novel C-terminal processing and internal proteolytic cleavage events. These results indicate that ProC-TEL provides a straightforward approach for profiling C-terminal peptides and identifying protein processing in complex biological samples.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Xu
authors.forename: Sung Bin Y
authors.initials: SB
authors.lastname: Shin
authors.forename: Samie R
authors.initials: SR
authors.lastname: Jaffrey
mesh_terms: D000818:Animals; D019921:Biotinylation; D043402:Cathepsin A / Q000378:metabolism; D002417:Cattle; D010455:Peptides / Q000032:analysis* / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D010455:Peptides; D012710:Serum Albumin, Bovine; D043402:Cathepsin A