title: Secretory immunoglobulin A from healthy human mothers' milk catalyzes nucleic acid hydrolysis.
abstract: The human milk secretory immune system is the first line of protection for the newborn infant against various pathogens. Secretory IgA (sIgA), the typical immunoglobulin found in secretions, can fight infections through many mechanisms. Using different methods, we have shown that sIgA from the milk of healthy women possesses DNAse and RNAse activities. The catalytic center is localized in the light chain of catalytic sIgA, while the DNA-binding center is predominantly formed by its heavy chain. The enzymic properties and substrate specificity of catalytic sIgA distinguish it from other known DNases and RNases. It is reasonable to assume that the milk DNA- and RNA-hydrolyzing antibodies are capable not only of neutralizing viral and bacterial nucleic acids by binding these antigens as well as by hydrolyzing them. The DNA-hydrolyzing activity of Abs raises the possibility that these catalytic Abs may provide protective functions for the newborn through the hydrolysis of viral and bacterial nucleic acids.
authors.affiliation: Novosibirsk Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Sciences. Nevinsky@niboch.nsc.ru
authors.forename: G A
authors.initials: GA
authors.lastname: Nevinsky
authors.forename: T G
authors.initials: TG
authors.lastname: Kanyshkova
authors.forename: D V
authors.initials: DV
authors.lastname: Semenov
authors.forename: A V
authors.initials: AV
authors.lastname: Vlassov
authors.forename: A V
authors.initials: AV
authors.lastname: Gal'vita
authors.forename: V N
authors.initials: VN
authors.lastname: Buneva
mesh_terms: D017151:Antibodies, Catalytic / Q000302:isolation & purification / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D005260:Female; D006801:Humans; D006868:Hydrolysis; D007071:Immunoglobulin A, Secretory / Q000302:isolation & purification / Q000378:metabolism*; D007147:Immunoglobulin Light Chains / Q000302:isolation & purification / Q000378:metabolism; D066298:In Vitro Techniques; D007231:Infant, Newborn; D008895:Milk, Human / Q000201:enzymology / Q000276:immunology*; D009696:Nucleic Acids / Q000378:metabolism*; D012260:Ribonucleases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D017151:Antibodies, Catalytic; D007071:Immunoglobulin A, Secretory; D007147:Immunoglobulin Light Chains; D009696:Nucleic Acids; D003851:Deoxyribonucleases; D012260:Ribonucleases