Solving Bioanalytical Problems by the Method of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

Abstract

The method of matrix-assisted laser desorption/ionization mass spectrometry has been used to solve some bioanalytical problems, which are difficult to analyze by general methods. For the selection of a proper laser wavelength and matrices, seven matrices were used with laser wavelength of 266 and 355 nm. The results show that with a wavelength of 355 nm better results could be obtained with most of the matrices. The molecular weight of cytochrome c, which was separated by gel electrophoresis and electro-blotted onto nitrocellulose membrane, was determined by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The accuracy was better than 0.1%, which is much higher than that of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The three components of protein mixture extracted from crude peanut oil was directly determined by MALDI-MS. The result also demonstrated that these proteins are in a free manner. Since these proteins are in a 2S bond, with the traditional method, SDS-PAGE, it is not possible to decide whether the proteins exist in a combination mode or in a free manner. Water-soluble polymers stained with dyes are used in the technique of two-phase aqueous solution, which is used for separating biomaterials. By using M ALDI, the number of the dye molecules that react with the polymer molecules can be determined, which is difficult to determine by other methods.