title: Metal ions bound to the human milk immunoglobulin A: metalloproteomic approach.
abstract: The presence of calcium, iron, and zinc bound to human milk secretory IgA (sIgA) was investigated. The sIgA components were first separated by two-dimensional polyacrylamide gel electrophoresis and then identified by electrospray ionization-tandem mass spectrometry (ESI MS MS). The metal ions were detected by flame atomic absorption spectrometry after acid mineralization of the spots. The results showed eight protein spots corresponding to the IgA heavy chain constant region. Another spot was identified as the transmembrane secretory component. Calcium was bound to both the transmembrane component and the heavy chain constant region, while zinc was bound to the heavy chain constant region and iron was not bound with the identified proteins. The association of a metal ion with a protein is important for a number of reasons, and therefore, the findings of the present study may lead to a better understanding of the mechanisms of action and of additional roles that sIgA and its components play in human milk.
authors: Institute of Biosciences, São Paulo State University-UNESP, Botucatu, SP, Brazil.
authors: Carla Mariane Costa
authors: CMC
authors: Pozzi
authors: Institute of Biosciences, São Paulo State University-UNESP, Botucatu, SP, Brazil. Electronic address: braga_ca@yahoo.com.br.
authors: Camila Pereira
authors: CP
authors: Braga
authors: Institute of Biosciences, São Paulo State University-UNESP, Botucatu, SP, Brazil.
authors: José Cavalcante Souza
authors: JCS
authors: Vieira
authors: Institute of Biosciences, São Paulo State University-UNESP, Botucatu, SP, Brazil.
authors: Bruna
authors: B
authors: Cavecci
authors: Institute of Biosciences, São Paulo State University-UNESP, Botucatu, SP, Brazil.
authors: João
authors: J
authors: Vitor de Queiroz
authors: Institute of Chemistry, University of Campinas-UNICAMP, Campinas, SP, Brazil.
authors: Herbert
authors: H
authors: de Souza Barbosa
authors: Institute of Chemistry, University of Campinas-UNICAMP, Campinas, SP, Brazil.
authors: Marco Aurelio Zezzi
authors: MAZ
authors: Arruda
authors: Institute of Chemistry, University of Campinas-UNICAMP, Campinas, SP, Brazil.
authors: Fabio Cesar
authors: FC
authors: Gozzo
authors: Institute of Biosciences, São Paulo State University-UNESP, Botucatu, SP, Brazil.
authors: Pedro de Magalhães
authors: PM
authors: Padilha
mesh_terms: D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis*; D008670:Metals / Q000032:analysis*; D008895:Milk, Human / Q000737:chemistry*; D040901:Proteomics / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization; D013054:Spectrophotometry, Atomic / Q000379:methods; D053719:Tandem Mass Spectrometry
chemical_list: D007071:Immunoglobulin A, Secretory; D008670:Metals
keywords: Electrospray ionization–tandem mass spectrometry; Flame atomic absorption spectrometry; Human milk; Metalloproteomics; Secretory IgA; Two-dimensional electrophoresis