Serine octamer reveals its structure

Abstract

After more than a decade of effort, researchers have identified the likely structure of the protonated serine octamer, an unusual complex first observed by mass spectrometry almost 20 years ago. The newly reported structure is the first that explains all of the experimental evidence, the researchers say (J. Am. Chem. Soc. 2018, DOI: 10.1021/jacs.8b02118). In 2001, researchers noticed that serine—unlike other amino acids—formed a charged, eight-membered cluster during electrospray ionization mass spectrometry (Anal. Chem. 2001, DOI: 10.1021/ac010284l). This octamer was by far the most abundant cluster size and always contained a single enantiomer, but its structure eluded researchers. Jongcheol Seo of the Fritz Haber Institute of the Max Planck Society and colleagues generated serine clusters via mass spectrometry, then gathered IR spectra using specialized low-temperature IR and mid-IR techniques. They compared those to the predicted IR spectra from cluster structures generated with advanced computer simu...