Takahashi N, Khoo K H, Suzuki N, Johnson J R, Lee Y C
Faculty of Pharmaceutical Sciences, Nagoya City University, Nagoya, 467-8603, Japan.
J Biol Chem. 2001 Jun 29;276(26):23230-9. doi: 10.1074/jbc.M101380200. Epub 2001 Apr 2.
N-Glycans from major glycoproteins of pigeon egg white (ovotransferrin, ovomucoid, and ovalbumins) were enzymatically released and were reductively aminated with 2-aminopyridine, separated, and structurally characterized by mass spectrometry and a three-dimensional mapping technique using three different columns of high performance liquid chromatography (HPLC) (Takahashi, N., Nakagawa, H., Fujikawa, K., Kawamura, Y., and Tomiya, N. (1995) Anal. Biochem. 226, 139-146). Twenty-five major N-glycan structures, all of them hitherto unknown, were identified as pyridylamino derivatives. Of these, 13 were neutral, 10 were monosialyl, and 2 were disialyl oligosaccharides. All N-glycans contain from one to four Galalpha(1,4)Galbeta(1,4) sequences at the nonreducing terminal positions and are devoid of fucose residues. N-Acetylneuraminic acids were alpha(2,6)-linked only to beta-galactose. The HPLC profiles of the N-glycans from four different glycoproteins were qualitatively very similar to each other, but not identical in the peak distributions. Monosialyl glycans were most abundant in all four glycoproteins, followed by neutral glycans. Disialyl glycans were lowest in ovotransferrin, and highest in ovomucoid. Triantennary structures with bisecting GlcNAc were predominant in ovotransferrin, and tetra-antennary (with and without bisecting GlcNAc-containing) structures were predominant in other glycoproteins. Penta-antennary structures (with a sialic acid and without bisecting GlcNAc residue) were also found in small quantities in all four glycoproteins. In contrast to the chicken egg white counterparts, which contain mostly high mannose and hybrid types, all N-glycan structures in the major pigeon egg white glycoproteins are complex type.
从鸽蛋清的主要糖蛋白（转铁蛋白、卵类粘蛋白和卵清蛋白）中酶解释放出N-聚糖，并用2-氨基吡啶进行还原胺化，然后分离，并通过质谱和使用三种不同的高效液相色谱（HPLC）柱的三维图谱技术进行结构表征（高桥直、中川浩、藤川健、川村洋、富宫直（1995年）《分析生物化学》226卷，139 - 146页）。鉴定出25种主要的N-聚糖结构，均为吡啶基氨基衍生物，此前均未知。其中，13种为中性，10种为单唾液酸，2种为双唾液酸寡糖。所有N-聚糖在非还原末端位置含有1至4个Galα(1,4)Galβ(1,4)序列，且不含岩藻糖残基。N-乙酰神经氨酸仅以α(2,6)连接至β-半乳糖。来自四种不同糖蛋白的N-聚糖的HPLC图谱在定性上彼此非常相似，但峰分布并不相同。单唾液酸聚糖在所有四种糖蛋白中最为丰富，其次是中性聚糖。双唾液酸聚糖在转铁蛋白中含量最低，在卵类粘蛋白中含量最高。带有平分型GlcNAc的三分支结构在转铁蛋白中占主导，而四分支（含或不含平分型GlcNAc）结构在其他糖蛋白中占主导。五分支结构（带有一个唾液酸且不含平分型GlcNAc残基）在所有四种糖蛋白中也有少量发现。与鸡蛋白的对应物大多含有高甘露糖型和杂合型不同，鸽蛋清主要糖蛋白中的所有N-聚糖结构均为复合型。
