Formation of deprotonated 2-imidazoline-4(5)-one product ions in the collision-induced dissociation of some serine-containing dipeptides

Abstract

a b s t r a c tA deprotonated 2-imidazoline-4(5)-one product ion was observed as a major fragment in the collisioninduced dissociation (CID) of several dipeptides containing serine at the C-terminal and an amino acid with an alkyl substituent at the N-terminal. This fragment becomes predominant at high collision energies. The same type of product ion was seen in the CID of cyclo(GlyGly). Labeling GlySer with O-18 suggests that the fragmentation may proceed through a symmetrical intermediate such as a deprotonated diketopiperazine. Density functional theory calculations of GlySer provided a possible mechanism for the fragmentation.

Twenty years of exceptional success: The molecular education and research consortium in undergraduate computational chemistry (MERCURY)

“…Padgett left the consortium, Gao ( Central State ) rejoined, and Kelly Anderson ( Roanoke College , physical), Aimée Tomlinson ( North Georgia College , physical), and Sudeep Bhattacharyay and Jim Phillips ( University of Wisconsin‐Eau Claire , biophysical and physical) joined, bringing the total to 17 MERCURY investigators. We published 79 peer‐reviewed papers, [ 159–237 ] or 1.5 papers/faculty/year, which is three times the rate for physical science faculty at undergraduate institutions. [ 46 ] The Shields group's collaboration with Brooks Pate resulted in a Science paper on the structures and energetics of the gas‐phase water hexamer, [ 160 ] which has been cited over 250 times.…”