Wei Z, Nishimura T, Yoshida S
Faculty of Applied Biological Science, Hiroshima University, Higashi-hiroshima, Japan.
J Dairy Sci. 2001 Dec;84(12):2584-90. doi: 10.3168/jds.S0022-0302(01)74712-1.
The presence of glycan at Asn-281 in bovine lactoferrin-a, which has a higher molecular weight than regular lactoferrin-b, was found in our previous study. The present work was performed to clarify the structures of the glycans linked to the five N-glycosylation sites in lactoferrin-a and to compare them with those of glycans linked to lactoferrin-b. In lactoferrin-a, the glycans linked to Asn-233 and Asn-545 were of the high-mannose type, whereas those present at Asn-368 and Asn-476 were complex-type ones. These glycans possessed heterogeneous structures. A comparative study of the glycans on bovine lactoferrin-a and bovine lactoferrin-b by HPLC showed that the structures of the glycans linked to Asn-368, Asn-476, and Asn-545 were very similar, the exception being the glycan linked to Asn-233. In addition, analysis of the structure of the glycan bound to Asn-281 present only in lactoferrin-a showed it possessed the heterogeneous structure of a complex-type glycan in which the structures Man3GlcNAc2, Man3GlcNAc4, Man3GlcNAc4Fuc are suggested to be present based on HPLC retention times only.
在我们之前的研究中发现，牛乳铁蛋白-a的天冬酰胺-281处存在聚糖，其分子量高于普通的乳铁蛋白-b。开展本研究是为了阐明与乳铁蛋白-a中五个N-糖基化位点相连的聚糖结构，并将它们与与乳铁蛋白-b相连的聚糖结构进行比较。在乳铁蛋白-a中，与天冬酰胺-233和天冬酰胺-545相连的聚糖为高甘露糖型，而存在于天冬酰胺-368和天冬酰胺-476处的聚糖为复合型。这些聚糖具有异质性结构。通过高效液相色谱法对牛乳铁蛋白-a和牛乳铁蛋白-b上的聚糖进行比较研究表明，与天冬酰胺-368、天冬酰胺-476和天冬酰胺-545相连的聚糖结构非常相似，唯一不同的是与天冬酰胺-233相连的聚糖。此外，对仅存在于乳铁蛋白-a中的与天冬酰胺-281相连的聚糖结构分析表明，它具有复合型聚糖的异质性结构，仅基于高效液相色谱保留时间推测其中存在Man3GlcNAc2、Man3GlcNAc4、Man3GlcNAc4Fuc结构。
