Covalent binding of the organophosphate insecticide profenofos to tyrosine on α- and β-tubulin proteins. (May 2018)

• Record Type: Journal Article
• Authors: Chu, Shaogang; Baker, Margaret R.; Leong, Gladys; Letcher, Robert J.; Li, Qing X.
• Is Part Of: Chemosphere. Volume 199(2018)
• Page Start: 154
• Page End: 159
• Publication Date: 2018-05
• Subjects: Adduct -- Exposure -- LC-Q-TOF-MS -- MALDI-TOF/TOF-MS -- Organophosphate -- Profenofos -- Tubulin; OPs Organophosphorus compounds -- HCCA α-cyano-4-hydroxycinnamic acid -- ACN acetonitrile -- DMSO dimethyl sulfoxide -- AChE acetylcholinesterase -- MALDI-TOF/TOF-MS matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry -- LC-Q-TOF-MS liquid chromatography quadrupole time-of-flight mass spectrometry -- DTT DL-dithiothreitol -- LC-ESI-TOF-MS liquid chromatography electrospray ionization time-of-flight mass mass spectrometry -- CPO chlorpyrifos oxon -- GTP guanosine 5-triphosphate; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.02.003
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Organophosphorus (OP) compounds can bind covalently to many types of proteins and form protein adducts. These protein adducts can indicate the exposure to and neurotoxicity of OPs. In the present work, we studied adduction of tubulin with the OP insecticide profenofos in vitro and optimized the method for detection of adducted peptides. Porcine tubulin was incubated with profenofos and was then digested with trypsin, followed by mass spectrometric identification of the profenofos-modified tubulin and binding sites. With solvent-assisted digestion (80% acetonitrile in digestion solution), the protein was digested for peptide identification, especially for some peptides with low mass. The MALDI-TOF-MS and LC-ESI-TOF-MS analysis results showed that profenofos bound covalently to Tyr83 in porcine α-tubulin (TGTY*83 R) and to Tyr281 in porcine β-tubulin (GSQQY*281 R) with a mass increase of 166.02 Da from the original peptide fragments of porcine tubulin proteins. Tyrosine adduct sites were also confirmed by MALDI-TOF/TOF-MS analysis. This result may partially explain the neurotoxicity of profenofos at low doses and prolonged periods of exposure. Graphical abstract: Image Highlights: Profenofos can form adducts with porcine tubulin. Profenofos binds covalently to Tyr83 of porcine α-tubulin and to Tyr281 of porcine β-tubulin. An in vitro method can detect tubulin-profenofos adducts and their adduct sites. Solvent-assisted trypsin digestion is simple and effective for preparation of adducted peptides.