The human plasma proteome: Analysis of Chinese serum using shotgun strategy

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Abstract
We have investigated the serum proteome of Han‐nationality Chinese by using shotgun strategy. A complete proteomics analysis was performed on two reference specimens from a total of 20 healthy donors, in which each sample was made from ten‐pooled male or female serum, respectively. The methodology used encompassed (1) removal of six high‐abundant proteins; (2) tryptic digestion of low‐ and high‐abundant proteins of serum; (3) separation of peptide mixture by RP‐HPLC followed by ESI‐MS/MS identification. A total of 944 nonredundant proteins were identified under a stringent filter condition (Xcorr ≥ 1.9, ≥2.2, and ≥3.75, ≤Cn ≥ 0.1, and Rsp ≥ 4.0) in both pooled male and female samples, in which 594 and 622 entire proteins were found, respectively. Compared with the total 3020 protein identifications confirmed by more than one laboratory or more than one specimen in HUPO Plasma Proteome Project (PPP) participating laboratories recently, 206 proteins were identified with at least two distinct peptides per protein and 185 proteins were considered as high‐confidence identification. Moreover, some lower abundance serum proteins (ng/mL range) were detected, such as complement C5 and CA125, routinely used as an ovarian cancer marker in plasma and serum. The resulting nonredundant list of serum proteins would add significant information to the knowledge base of human plasma proteome and facilitate disease markers discovery.