Title : Glycoproteomics: identifying the glycosylation of
prostate specific antigen at normal and high isoelectric points by LC-MS/MS
Abstract :
- Prostate specific antigen ( PSA ) is currently used as a biomarker to diagnose prostate cancer
- PSA testing has been widely used to detect and screen prostate cancer
- However, in the diagnostic gray zone, the PSA test does not clearly distinguish between benign prostate hypertrophy and prostate cancer due to their overlap
- To develop more specific and sensitive candidate biomarkers for prostate cancer, an in-depth understanding of the biochemical characteristics of PSA (such as glycosylation) is needed
- PSA has a single glycosylation site at Asn69 , with glycans constituting approximately 8% of the protein by weight
- Here, we report the comprehensive identification and quantitation of N-glycans from two PSA isoforms using LC-MS/MS
- There were 56 N-glycans associated with PSA , whereas 57 N-glycans were observed in the case of the PSA-high isoelectric point ( pI ) isoform ( PSAH )
- Three sulfated/phosphorylated glycopeptides were detected, the identification of which was supported by tandem MS data
- One of these sulfated/phosphorylated N-glycans, HexNAc5Hex4dHex1s/p1 was identified in both PSA and PSAH at relative intensities of 0.52 and 0.28%, respectively
- Quantitatively, the variations were monitored between these two isoforms
- Because we were one of the laboratories participating in the 2012 ABRF Glyco protein Research Group (gPRG) study, those results were compared to that presented in this study
- Our qualitative and quantitative results summarized here were comparable to those that were summarized in the interlaboratory study