Analytical applications of matrix-assisted laser desorption and ionization mass spectrometry

Abstract

Matrix-assisted laser desorption ionization mass spectrometry (LDI-MS) has been used successfully for monitoring and quality control of a protein synthesis and for identification of by-products. In a first example it is shown that LDI-MS can be used to determine the amount and mass of the protein and the impurities in a commercially available protein product. The second example describes a protein synthesis where LDI-MS is the analytical method of choice which allows determination of the endpoint of the synthesis, the purity of the product and the obtained by-products. As a third example a synthesis of hirudin by recombinant DNA technology is shown where degraded r-hirudin with one or more missing amino acids are easily detected and distinguished from the complete r-hirudin. The mass determination and identification of the missing amino acids is presented. The results of LDI-MS are compared with results of state-of-the art analytical methods like reversed-phase high-performance liquid chromatography, sodium dodecyl sulphate-polyacrylarmide gel electrophoresis, and capillary electrophoresis.