title: Analysis of staphylococcal enterotoxin A in milk by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.
abstract: Staphylococcal enterotoxin A (SEA) is an exotoxin excreted mainly by Staphylococcus aureus and nowadays is the most prevalent compound in staphylococcal food poisoning worldwide. SEA is highly heat-resistant, and usual cooking times and temperatures are unlikely to completely inactivate it. A procedure for extraction of this toxin based on protein precipitation with a mixture of dichloromethane and acidified water was used before SDS-PAGE separation of soluble proteins. Finally, bands of interest were excised from the gel and in-gel enzymatic digestion was done. SEA from pasteurized milk was detected with matrix-assisted laser-desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. Nineteen peptides (range 800-2400 Da) were identified as products of trypsin cleavage of the SEA standard with a score of 204 and 73% coverage of the protein sequence, whereas thirteen peptides were revealed for SEA extracted from milk with a score of 148 and 58% sequence coverage obtained. This procedure has been applied successfully for identification of SEA in milk.
authors: Department of Preventive Medicine and Public Health, Faculty of Pharmacy, University of Valencia, Av. Vicent Andrés Estellés s/n, 46100 Burjassot, Spain. m.isabel.sospedra@uv.es
authors: Isabel
authors: I
authors: Sospedra
authors: Carla
authors: C
authors: Soler
authors: Jordi
authors: J
authors: Mañes
authors: José Miguel
authors: JM
authors: Soriano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D004768:Enterotoxins / Q000737:chemistry / Q000302:isolation & purification*; D008892:Milk / Q000382:microbiology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013211:Staphylococcus aureus / Q000302:isolation & purification*
chemical_list: D004768:Enterotoxins; D010455:Peptides; C026066:enterotoxin A, Staphylococcal