生殖功能的調節主要由糖蛋白激素，卵泡刺激素（FSH）、促甲狀腺激素（TSH）、黃體生成素（LH）和絨毛膜促性腺激素（hCG）進行。糖蛋白激素包含α 亞基 &  β 亞基

 hCG、FSH 和 LH 有相同的α 亞基，包含 92 個氨基酸，

 hCG、FSH 和 LH 之 β 亞基對於所有三種激素是特異性和獨特的，可引發不同的生物學和免疫學特性。

聚醣glycans在促性腺激素與其各自受體的結合中發揮著重要作用，識別相關聚醣及其藥理學特性非常重要。

蛋白質糖基化Protein glycosylation 是一種複雜的翻譯後修飾post-translational modification (PTM)，涉及glycans在特定位點的附著，最常見的是天冬酰胺（N 連接）或絲氨酸/蘇氨酸（O 連接）殘基。糖基化glycosylation模式在蛋白質的溶解度、穩定性和生物活性中起著至關重要的作用。

新的聚醣 glycan是一種四觸角物種tetra antennary ， FSH 與受體的結合中發揮重要作用，具有更高的生物活性、更低的清除率和更長的半衰期。

由於糖基化的差異，糖蛋白的生物活性和半衰期可能不同。

質譜儀mass spectrometry MS技術的進步，可以鑑定微量的相關聚醣。MS 可進行定量和定性分析，例如分子量測定、結構闡明或序列測定。

 https://www.sciencedirect.com/science/article/abs/pii/S1642431X18300949

https://link.springer.com/article/10.1007/s00216-011-4923-5

Glycan mapping of recombinant human follicle stimulating hormone by mass spectrometry

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• In humans, regulation of reproductive functions are carried out mainly by glycoprotein hormones namely follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), luteinizing hormone (LH) and chorionic gonadotropin (CG). 
• Since glycans play an important role in binding of gonadotropins with their respective receptors, it is important to identify associated glycans and their pharmacological properties not only for the disease manipulation but also for making more efficacious and safer recombinant versions. 
• Protein glycosylation is a complex post-translational modification (PTM) involving enzyme mediated attachment of glycans at specific sites, most commonly at Asparagine (N-linked) or Serine/Threonine (O-linked) residues. The glycosylation pattern plays a critical role in the solubility, stability and bioactivity of proteins. 
• With the advancement of mass spectrometry, it is possible to identify minute quantity of associated glycans. 
• The new glycan was a tetra antennary species that may have important role in binding of FSH with receptor with higher biological activity as well as lower clearance rate and higher half-life.
• The α-subunit contains 92 amino acids and is identical in hCG, FSH and LH (Table 1) while β-subunit are specific and unique for all the three hormones for eliciting differential biological and immunological properties. 
• Due to differences in the glycosylation, glycoprotein may differ in bioactivities and half-life. 
• MS allows both quantitative and qualitative analysis like determination of molecular mass, structure elucidation or sequence determination. 

Analysis of recombinant human follicle-stimulating hormone (FSH) by mass spectrometric approaches

• Thorough analysis of the heterodimeric heavily glycosylated protein of rFSH is a prerequisite for the evaluation of production batches as well as for the determination of “essential similarity” of new biosimilars. 
• The concerted application of different liquid chromatography-mass spectrometry methods enabled the complete depiction of the primary structure of this pituitary hormone. 
• Sequence coverage of 100% for the α- as well as the β-chain was achieved with tryptic peptides. 
• Most of these peptides could be verified by tandem mass spectrometry. Site-specific analysis of all four glycosylation sites was, however, not possible with tryptic but with chymotryptic peptides. Quantification of the glycoforms of each glycopeptide was accomplished with the software MassMap®. Both protein subunits gave interpretable mass spectra upon S-alkylation and separation on a C5 reversed-phase column. Glycan isomer patterns were depicted by separation on porous graphitic carbon, using mass spectrometric detection for the evaluation of the glycopeptide liquid chromatography-electrospray ionization data. The currently marketed product Gonal-f™ and a potential biosimilar were compared with the help of these procedures.