Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Biological Noncovalent Complexes

Book excerpt: ABSTRACT: Noncovalent chemistry is the basis of many important biological interactions, including enzyme-ligand complex formation. As these interactions are typically weaker than covalent bonds, special analysis methods are needed for studying noncovalent complexes. Using gentle ionization methods like electrospray ionization (ESI), noncovalent complexes can be preserved and analyzed by mass spectrometry. Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) provides superior mass accuracy, resolving power, and tandemin- time capabilities. Among the dissociation techniques available are in-source collision-induced dissociation and infrared multiple photon dissociation (IRMPD). Dynamic combinatorial chemistry uses a special type of library wherein reversible binding between library members and between library members and a target molecule expands the potential number of strong complex interactions. Here, several 2', 3'-cyclic monophosphate nucleotides were incubated with Ribonuclease A to generate enzyme-ligand complexes. Enzymatic activity may drive the library members to form RNA chains via phosphodiester bond generation. This dissertation shows the method development for screening a cyclic nucleotide-based dynamic combinatorial library for tight-binding ligands of Ribonuclease A using ESI-FTICR-MS.