Human milk antibodies with polysaccharide kinase activity

详细信息    查看全文

• 作者：Natal’ ; ya A. Karataeva ; Dmitry Gorbunov ; Ivan V. Prokudin ; Valentina N. Buneva ; Anna A. Kulminskaya ; Kirill N. Neustroev and Georgy A. Nevinsky
• 关键词：Human milk ; Catalytic sIgA ; Phosphorylation of polysaccharides
• 刊名：Immunology Letters
• 出版年：2006
• 出版时间：28 February 2006
• 年：2006
• 卷：103
• 期：1
• 页码：58-67
• 全文大小：314 K

文摘

It was shown for the first time that a small fraction of milk secretory IgA (sIgA) is tightly bound to oligosaccharides (oligoSACs) and polysaccharides (polySACs). The ability of sIgA to phosphorylate oligo- and polysaccharides was shown to be an intrinsic property of this antibody. In contrast to known kinases, sIgAs with polysaccharide kinase activity can transfer phosphoryl group to oligo- and polysaccharides not only from [γ-³²P]ATP but can also use [³²P]orthophosphate as a substrate of phosphorylation reaction. An extremely unusual property of polysaccharide kinase Abs is their high affinity for orthophosphate (K_m = 15–77 μM), and orthophosphate is a better substrate than ATP. Two first examples of natural abzymes (Abzs) with synthetic activity were milk sIgA with protein and lipid kinase activities. Polysaccharide kinase sIgA of human milk is the third example of natural antibodies (Abs) with synthetic activity.