Biomolecular condensation via ultraviolet excitation in vacuo

Recently, we reported that 157 nm vacuum ultraviolet irradiation (VUV) of proton-bound peptide dimers trapped in a vacuum, results in the elimination of water and formation of a peptide bond [J. Am. Chem. Soc. 133 (2011) 15834–15837]. Here, we further explore the ability to form a covalent bond between biomolecular ions with photoexcitation. Photoexcitation of long-lived charge-bound complexes appears to be a general phenomenon, resulting in the loss of water and the formation of covalent bonds between many types of molecules. Several examples are described, including: the linear coupling of amino acid chains that produce octapeptides from tetrapeptide complexes; inter-molecular cross-linking of amino acid side chains, and glycosidic bond formation between disaccharide complexes. Simple mechanisms for each case are proposed.

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► We demonstrate the gas-phase synthesis of several different biomolecules using 157 nm vacuum ultraviolet irradiation (VUV) of charge-bound dimers.
► Several examples include the linear coupling of amino acid chains, inter-molecular cross-linking, and glycosidic bond formation.
► Simple mechanisms for each case are proposed.