New Matrices In Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry And Their Applications

Because DIOS mass spectrometry presents little interference for the analysis of small molecules in the low-mass range, it is easy to monitor the digestion product formation of substrate with enzymatic reaction, and thereby to measure activity of the immobilized enzyme. Furthermore, a method for peptide mapping analysis by in-situ digestion of proteins on the porous silicon surface modified by enzyme trypsin, combined with matrix-assisted laser desorptio/ionization time-of-flight mass spectrometry has been developed. Good sequence coverage could be obtained for proteins of cytochrome C and BSA.Iminodiacetic acid (IDA)-1, 2-epoxy-9-decene modified porous silicon surface allows the removal of the contaminants in samples prior to MALDI mass spectrum analysis by simply washing the porous silicon surface. The carboxylic end groups on porous silicon can be used to selectively bind and concentrate target species in the sample solutions. Furthermore, the IDA-derivatized porous silicon can be transferred to Fe3+-IDA-derivatized porous silicon when needed, and the obtained porous silicon surface can specifically trap and effectively concentrate phosphopeptides from the tryptic digest of phosphoprotein and further analyzed by MALDI MS.Herein, a new MALDI matrix, 3, 4-diaminobenzophone (DABP), has been foundwith high tolerance against contaminants in sample solution for MALDI MS analysis. Furthermore, it has been found that this matrix can also effectively suppress the cation ion adduction of the peptides in the presence of high concentrations of metal ions in sample solution.Analysis of low molecular weight compounds with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) has been developed by using carbon nanotube obtained from coal by arc discharge as matrix. The carbon nanotube matrix functions as substrate to trap analytes of peptides, organic compounds andβ-cyclodextrin deposited on its surface. It has been found that carbon nanotube can transfer energy to analytes under laser irradiation, which makes analytes to be well desorbed/ionized. It is believed that this work will open a new field for applications of carbon nanotubes.