WP376 Structural characterization of alginate and other complex glycans using high resolution ion mobility - mass spectrometry
Nick Tomczyk, Laetitia Denbigh, Helene Rogniaux, David Ropartz, Jakub Ujma, Kevin Giles
Waters Corporation, Wilmslow, Cheshire, United Kingdom
INRA, UR1268 Biopolymers Interactions Assemblies, Nantes, N/A, France
Introduction
Alginates are polysaccharides from brown algae. They have gelling properties which make them interesting for industries in food and health applications. The gelling property of alginates depends on the relative proportion of guluronate homopolymeric blocks. It is therefore crucial to develop analytical methods able to characterize finely their structure, and differentiate guluronate and mannuronate blocks, especially as they cannot be differentiated by their mass and cannot be easily separated by conventional LC systems coupled to MS. In this study we will use a cyclic IMS-enabled research platform to separate and better characterize the G and M blocks in alginates. Other complex glycans such as mixed linked-glucan were analyzed on this platform to help define enzymes specificities and mode of action.
Methods
Pure samples of β-D-Mannuronic acid oligomer and α-L-Guluronic acid oligomer (pure degree of polymerisation 5) were analysed either on their own or in a mixture on a modified SYNAPT HDMS system fitted with a prototype cyclic IMS device and dual gain ADC. This cyclical IMS device offers IMS resolutions in excess of 200 providing a route to High-resolution-IMS-MS (HR-IMS MS) and HR-IMS MS/MS experiments. A sample containing a mix of structures was also analysed in the same conditions. HR-IMS MS and HR-IMS MS/MS experiments were also carried out on Β-linked glucans samples (of degree of polymerisation 4) with different linkages
Preliminary Data or Plenary Speakers Abstract
Pure β-D-Mannuronic acid oligomer, pure α-L-Guluronic acid oligomer and a 1:1 mix of these two were infused directly into a modified SYNAPT HDMS system fitted with a prototype cyclic IMS device. Arrival times of the two molecules were measured after multiple passes of the cyclic cell, each pass being 1m in length. After 2 passes in the cyclic IMS, both molecules were measured at a single different arrival time. In the mixture, the two compounds were clearly separated although not to baseline.The separation was greatly improved when the number of passes increased. After 6 passes, in the pure α-L-Guluronic sample, the main drift time arrival peak was dividing into two, suggesting the presence of another conformation in the sample.A complex mixture of alginate sample (DP5) was also analysed. Arrival times corresponding to those of pure β-D-Mannuronic acid oligomer and pure α-L-Guluronic acid oligomer were observed (in different proportions). Additional peaks, probably corresponding to molecules with a mixture of G and M blocks were also detected.Additional MSMS experiments will be carried out on all the different peaks in order to further characterize them.
Novel Aspect
Separating and characterizing complex glycan structures such as alginates on a cyclic IMS-enabled research platform