BIO-AFFINITY CHARACTERIZATION MASS-SPECTROMETRY

A new approach, bio-affinity characterization mass spectrometry (BACMS ), aimed at providing a more rapid, sensitive and potentially more fle xible alternative to techniques presently employed for the characteriz ation of noncovalent interactions in mixtures, such as would be encoun tered in combinatorial chemistry, is presented, BACMS avoids some of t he difficulties and potential artifacts associated with affinity chrom atography since the noncovalent associations occur in solution; thus, BACMS avoids the requirement of solid support media and the developmen t of non-interfering linker species. This paper describes the conceptu al basis for the methodology and its potential use in applications whi ch include the screening of high affinity ligands in support of new dr ug development. BACMS exploits new Fourier-transform ion cyclotron res onance (FTICR) mass spectrometry technologies which, when coupled to e lectrospray ionization (ESI), allow the investigation of specific nonc ovalent complexes formed in solution. BACMS utilizes the well-known at tributes of FTICR, such as the high resolution mass analysis and (MS)( n) (n greater than or equal to 2) capabilities; however, it is even mo re directly a result of recently developed techniques involving quadru polar excitation, such as selected-ion accumulation. These tools are d emonstrated and the results illustrate the extraordinary sensitivity a chievable (solution concentrations of 1x10(-9) M without the use of se parations prior to ESI). Thus, the new capabilities demonstrated here, in conjunction with ESI, will be useful for the investigation of very low relative concentration noncovalent association directly from solu tion, and promote a faster alternative for combinatorial mixture scree ning and analysis.