COMBINING MALDI MASS-SPECTROMETRY AND BIOMOLECULAR INTERACTION ANALYSIS USING A BIOMOLECULAR INTERACTION ANALYSIS INSTRUMENT

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-M S) has been combined with biomolecular interaction analysis (BIA) in a Biacore instrument. A method has been developed for the recovery of t he affinity-bound molecules from the sensor chip in a few microliters ready for mass spectrometric analysis. The procedure is illustrated wi th two molecular systems which exemplify antibody-antigen and DNA-prot ein interactions. In both cases, femtomole quantities of the affinity- bound proteins were eluted and subsequently detected by MALDI-MS. Wher eas the Biacore analysis yields the surface concentration of protein b ound to the sensor chip, identity of the bound compounds is revealed i n the second step by accurate molecular mass determination, Combining the information of the two analyses allows calculation of the total su rface molar concentration of affinity-bound molecules.