MALDI-ISD Measurements Using Both the SpiralTOF Mode and the LinearTOF Mode
Matrix assisted laser desorption/ionization (MALDI) combined with in-source decay (ISD) is a useful tool for doing top-down sequencing of intact proteins. In this work, we measured and compared the ISD fragment ions generated for several proteins by using both the high resolution MALDI-Spiral mode and the high sensitivity MALDI-Linear mode available on the JEOL SpiralTOF MALDI-MS system.
Myoglobin and Bovine serum albumin (BSA) protein samples were separately dissolved into 0.1% trifluoroacetic acid aqueous with the concentration fixed at 10 pmol/μL. 1,5-diaminonaphthalene (DAN), which can provide good S/N for ISD fragment ions , was used as the MALDI matrix. The DAN matrix was dissolved to 0.1% trifluoroacetic acid aqueous/ 50% acetonitrile with the matrix concentration fixed at 10 mg/mL. Subsequently, the matrix and the sample solutions were mixed 1/1 (v/v), and then 1 μL of each solution was deposited and dried on the MALDI target plate. Afterwards, each sample was analyzed in triplicate on the JEOL JMS-3000 SpiralTOF by using both the SpiralTOF mode and the LinearTOF mode.