Analysis of Reaction Products of Lysozyme under the Explosion Condition by Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry

Abstract

Identification and determination of explosives and explosive residues were a subject of continuing strong interest in analytical chemistry and forensic science. In this paper, the reaction products of lysozyme under the explosion condition were analyzed by a MALDI-TOFMS (Matrix-assisted laser desorption ionization time-of-flight mass spectrometry) method. There was no difference in the tryptic digest between the normal lysozyme and the reaction products generated by detonator, while some adduct peaks such as [MH+17]+, [MH+18]+, [MH+28]+, [MH+32]+, and [MH+44]+ were discovered in the explosives. This may be attributed to the reaction between the lysozyme and the active small molecule gases such as NH3, H2O, CO/N2, O2, CO2, which were generated during the explosion. Characteristic peaks which were produced by lysozyme and the active small molecule gases from different explosives can be used to discriminate the six explosives. For example, H2O molecules which were generated during the exploration by tri-nitrotoluene (TNT) can specifically react with VFGRCELAAAMKRHGLDNYR (m/z 2307) to produce a characteristic peak at m/z 2325 (2307+18). Also, H2O molecules which were generated by hexahydro-1,3,5-trinitroazine (RDX) can completely react with IVSDGNGMNAWVAWRNRCK (m/z 2177) to produce a characteristic peak at m/z (2177 + 18). Characteristic peak at m/z 1301 was produced by GYSLGNWVCAAK (m/z 1269) and O2 molecules for the identification of pentaerythritol tetranitrate (PETN). While for black powder, O2 and H2O can both react with IVSDGNGMNAWVAWR (m/z 1676) to produce product ions peaks at m/z 1694 and 1708. However, only the O2 molecules can react with IVSDGNGMNAWVAWR for pyrotechnic composition. As for ammon explosive, which is a mixture of inorganic explosives and organic explosives, CO2 molecules can react with a plurality of reaction sites of lysozyme to produce a series of characteristic peaks signals such as m/z 1313 (1269+44), 1720 (1676+44), 1848 (1804+44), 2722 (2678+44).