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: Isabel Sospedra, Carla Soler, Jordi Mañes, José Miguel Soriano
• Journal: Analytical and bioanalytical chemistry (Anal Bioanal Chem) Vol. 400 Issue 5 Pg. 1525-31 (May 2011) ISSN: 1618-2650 [Electronic] Germany
• PMID: 21442364 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Enterotoxins
• Peptides
• enterotoxin A, Staphylococcal

Topics

• Amino Acid Sequence
• Animals
• Cattle
• Enterotoxins (chemistry, isolation & purification)
• Milk (microbiology)
• Molecular Sequence Data
• Peptides (chemistry, isolation & purification)
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization (methods)
• Staphylococcus aureus (isolation & purification)