MOLECULAR-MASS AND CARBOHYDRATE STRUCTURE OF PROSTATE-SPECIFIC ANTIGEN - STUDIES FOR ESTABLISHMENT OF AN INTERNATIONAL PSA STANDARD
MOLECULAR-MASS AND CARBOHYDRATE STRUCTURE OF PROSTATE-SPECIFIC ANTIGEN - STUDIES FOR ESTABLISHMENT OF AN INTERNATIONAL PSA STANDARD
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DOI：
10.1002/pros.2990270403
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发表时间：
1995-10-01
期刊：
影响因子：
2.8
通讯作者：
LABRIE, F
中科院分区：
文献类型：
--
作者：
BELANGER, A;VANHALBEEK, H;LABRIE, F
尽管前列腺特异性抗原（PSA）作为前列腺癌的标志物被广泛接受，但这种分子尚未完全表征。然而，过去的研究已经充分确定，使用氨基酸和cDNA测序技术，PSA含有237个氨基酸，分子的肽部分的分子量为26，079 Da。本研究报告分析这种蛋白质的离子喷雾质谱（ISMS）和分析其碳水化合物部分的NMR光谱。ISMS检测到的主要PSA分子种类的相对分子质量（M（r））为28，430，表明PSA含有M（r）2，351的碳水化合物残基，碳水化合物的总百分比为8.3%。然而，通过SDS-PAGE分析PSA显示M（r）为32，000至33，000，表明后一种技术高估了分子量。PSA碳水化合物链的完整一级结构通过NMR光谱结合碳水化合物组成分析来确定。实验测定的PSA的碳水化合物含量证实，在蛋白质中仅占据一个N-糖基化位点。拟定的碳水化合物结构是N-乙酰乳糖胺型的双触角N-连接寡糖，在两个分支的末端各有一个唾液酸基团。此外，我们的数据表明，类似于70%的PSA分子在核心壳二糖部分中含有岩藻糖基团。基于通过离子喷雾质谱法测量的PSA的M（r）28，430和根据分子肽部分的共有序列计算的M（r）26，079，该碳水化合物结构的计算分子量（M（r）2，351.8）与碳水化合物基团的预测分子量非常一致。因此，PSA的ISMS被认为是一种方便可靠的质量控制方法，是实现这一非常重要的肿瘤标志物在前列腺疾病，特别是前列腺癌的检测和监测方面的国际标准化的不可或缺的一步。(C)1995年Wiley-Liss，Inc.
Despite the widely accepted use of prostate specific antigen (PSA) as a marker of prostate cancer, this molecule has not yet been completely characterized. Past studies have well established, however, using both amino acid and cDNA sequencing techniques, that PSA contains 237 amino acids, with a molecular mass of 26,079 Da for the peptide moiety of the molecule. The present study reports analysis of this protein by ion spray mass spectrometry (ISMS) and analysis of its carbohydrate moiety by NMR spectroscopy. The predominant PSA molecular species detected by ISMS was at relative molecular mass (M(r)) of 28,430, indicating that PSA contains a carbohydrate residue of M(r) 2,351, for a total percentage of carbohydrate of 8.3%. Analysis of PSA by SDS-PAGE, however, showed a M(r) of 32,000 to 33,000, suggesting an overestimation of the molecular weight by the latter technique. The complete primary structure of the PSA carbohydrate chain was determined by NMR spectroscopy in combination with carbohydrate composition analysis. The experimentally determined carbohydrate content of PSA confirms that only one N-glycosylation site is occupied in the protein. The proposed carbohydrate structure is a diantennary N-linked oligosaccharide of the N-acetyllactosamine type, with a sialic acid group at the end of each of the two branches. In addition, our data indicate that similar to 70% of the PSA molecules contain a fucose group in the core chitobiose moiety. The calculated molecular weight of this carbohydrate structure (M(r) 2,351.8) is in excellent agreement with the predicted molecular weight of the carbohydrate group, based on the M(r) 28,430 for PSA measured by ion spray mass spectrometry and M(r) 26,079 calculated from the consensus sequence for the peptide portion of the molecule. ISMS of PSA is thus proposed as a convenient and reliable method of quality control, an indispensible step towards international standardization of this very important tumor marker for detection and monitoring of prostatic diseases, especially prostate cancer. (C) 1995 Wiley-Liss, Inc.