IRMPD Spectroscopy Sheds New (Infrared) Light on the Sulfate Pattern of Carbohydrates

Abstract

IR spectroscopy of gas phase ions is proposed to resolve positional isomers of sulfated carbohydrates. Mass spectrometric fingerprints and gas phase vibrational spectra in the near and mid IR regions were obtained for sulfated monosaccharides, yielding unambiguous signatures of sulfated isomers. We report the first systematic exploration of the biologically relevant but notoriously challenging deprotonated state in the near IR region. Remarkably, anions displayed very atypical vibrational profiles, which challenge the well--established DFT (Density Functionnal Theory) modeling. The proposed approach was used to elucidate the sulfate patterns in glycosaminoglycans - a ubiquitous class of mammalian carbohydrates - which is regarded as a major challenge in carbohydrate structural analysis. Isomeric glycosaminoglycan disaccharide from heparin and chondroitin sources where resolved, highlighting the potential of InfraRed Multiple Pho--ton Dissociation spectroscopy as a novel structural tool for carbohydrates.

Unraveling the unknown areas of the human metabolome: the role of infrared ion spectroscopy

“…IR-IS has evolved in little more than a decade from an experimental technique in academic labs studying fundamental molecular physics (Lemaire et al 2002 ; Aleese et al 2006 ; Oomens et al 2006 ; Fridgen 2009 ; Polfer and Oomens 2009 ) to its current state, in which it is a demonstrated (bio)analytical technique for the identification of small molecules in complex mixtures (Martens et al 2017a , b ), though still limited to user facilities or state-of-the-art laboratories housing the most advanced tuneable infrared laser technology. In the past decade, IR-IS has been used to identify and characterize the molecular structures of many classes of chemical compounds including amino acids (Polfer et al 2005 , 2006a ; Correia et al 2008 ; Rodgers et al 2008 ; Oomens and Steill 2009 ; Scuderi et al 2011 ), nucleotides and bases (Salpin et al 2007 ; Chiavarino et al 2013 ), peptides and proteins (Balaj et al 2008 ; Polfer et al 2008 ; Yoon et al 2008 ; Fukui and Takahashi 2012 ; Martens et al 2012 , 2015 , 2016a ; Stedwell et al 2012 ; Scuderi et al 2015 ; Dunbar et al 2017 ), saccharides (Martens et al 2017b ; Polfer et al 2006b ; Cagmat et al 2010 ; Contreras et al 2012 ; Schindler et al 2014 , 2017 ), neurotransmitters (Lagutschenkov et al 2010 , 2011 ), and a variety of other mainly small organic compounds and reaction products (Martens et al 2017a ; MacAleese and Maître 2007 ; Rummel et al 2011 ; De Petris et al 2013 , 2016b ; Warnke et al 2015 ; Cismesia et al 2016 ; Seo et al 2016 ; Schäfer et al 2017 ; Gorlova et al 2017 ). Here we outline various ways IR-IS can currently be utilized by the metabolomics community.…”

Cryogenic Vibrational Spectroscopy Provides Unique Fingerprints for Glycan Identification

“…Polfer and co-workers [24, 25] successfully combined IRMPD with high-resolution MS for the identification of disaccharides, but the room temperature IRMPD spectra were too broad to uniquely identify isomeric disaccharides in a mixture. Compagnion and co-workers [26, 27] have recently implemented a similar approach. In a very recent paper, Mucha et al [28] used helium droplets to obtain spectroscopic fingerprints of oligosaccharides, showing that sufficiently resolved spectra could indeed distinguish the various types of isomerism, albeit with an admittedly complex experimental set-up.…”

Anomeric memory of the glycosidic bond upon fragmentation and its consequences for carbohydrate sequencing

“…With the integration of IR spectroscopy to mass spectrometry (IRMPD spectroscopy), the applicability of this highly relevant spectral range has been generalised to non-derivatised carbohydrates. Several groups have reported diagnostic fingerprints of monosaccharides isomers in this spectral range, including hexoses 28 , 29 , hexuronic acids 30 , 31 , N -acetyhexosamines 32 , 33 , and sulfated and phosphorylated monosaccharides 34 – 36 . Recently, we have also reported the spectroscopic identification of oligosaccharide isomers 36 , 37 .…”