title: Human milk antibodies with polysaccharide kinase activity.
abstract: 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 [gamma-(32)P]ATP but can also use [(32)P]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 microM), 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.
authors.affiliation: Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, Lavrentieva Ave. 8, Novosibirsk 630090, Russia.
authors.forename: Natal'ya A
authors.initials: NA
authors.lastname: Karataeva
authors.forename: Dmitry
authors.initials: D
authors.lastname: Gorbunov
authors.forename: Ivan V
authors.initials: IV
authors.lastname: Prokudin
authors.forename: Valentina N
authors.initials: VN
authors.lastname: Buneva
authors.forename: Anna A
authors.initials: AA
authors.lastname: Kulminskaya
authors.forename: Kirill N
authors.initials: KN
authors.lastname: Neustroev
authors.forename: Georgy A
authors.initials: GA
authors.lastname: Nevinsky
mesh_terms: D017151:Antibodies, Catalytic / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D002384:Catalysis; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D008895:Milk, Human / Q000737:chemistry / Q000201:enzymology* / Q000276:immunology; D010766:Phosphorylation; D010770:Phosphotransferases / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*
chemical_list: D017151:Antibodies, Catalytic; D007071:Immunoglobulin A, Secretory; D011134:Polysaccharides; D010770:Phosphotransferases