Characterization of Glycans in a Lactoferrin Isoform, Lactoferrin-a

¹ Faculty of Applied Biological Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-hiroshima, Hiroshima, Japan 739-8528

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-man-nose 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.

Key Words: lactoferrin-a • lactoferrin-b • glycan

Submitted on April 10, 2001
Accepted on July 16, 2001

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