Feasibility of using atmospheric pressure matrix-assisted laser desorption/ionization with ion trap mass spectrometry in the analysis of acetylated xylooligosaccharides derived from hardwoods and Arabidopsis thaliana

Abstract

The atmospheric pressure matrix-assisted laser desorption/ionization with ion trap mass spectrometry (AP-MALDI-ITMS) was investigated for its ability to analyse plant-derived oligosaccharides. The AP-MALDI-ITMS was able to detect xylooligosaccharides (XOS) with chain length of up to ten xylopyranosyl residues. Though the conventional MALDI-time-of-flight/mass spectrometry (TOF/MS) showed better sensitivity at higher mass range (>m/z 2,000), the AP-MALDI-ITMS seems to be more suitable for detection of acetylated XOS, and the measurement also corresponded better than the MALDI-TOF/MS analysis to the actual compositions of the pentose- and hexose-derived oligosaccharides in a complex sample. The structures of two isomeric aldotetrauronic acids and a mixture of acidic XOS were elucidated by AP-MALDI-ITMS using multi-stages mass fragmentation up to MS(3). Thus, the AP-MALDI-ITMS demonstrated an advantage in determining both mass and structures of plant-derived oligosaccharides. In addition, the method of combining the direct endo-1,4-β-D-xylanase hydrolysis of plant material, and then followed by AP-MALDI-ITMS detection, was shown to recognize the substitution variations of glucuronoxylans in hardwood species and in Arabidopsis thaliana. To our knowledge, this is the first report to demonstrate the acetylation of glucuronoxylan in A. thaliana. The method, which requires only a small amount of plant material, such as 1 to 5 mg for the A. thaliana stem material, can be applied as a high throughput fingerprinting tool for the fast comparison of glucuronoxylan structures among plant species or transformants that result from in vivo cell wall modification.

Reduced Wall Acetylation Proteins Play Vital and Distinct Roles in Cell Wall O-Acetylation in Arabidopsis

“…S2). The samples were treated with GH10 endo-1,4-b-xylanase to specifically release xylo-oligosaccharides (XOSs) for the mass spectrometry analysis (Chong et al, 2011). The percentage peak intensity was calculated by dividing intensity of a single acidic XOS peak over intensity of all acidic XOS peaks (Supplemental Fig.…”

“…The pellet was then dried in a desiccator. An amount of 3 mg of Arabidopsis AIR was incubated in 1 mL 20 mM NaOAc, pH 5.0, with 20,000 nkat GH10 endo-1,4-b-D-xylanase from Aspergillus aculeatus per gram AIR, at 40°C for 24 h. The liberated XOSs were purified using Hypersep Hypercarb Porous Graphitized Carbon columns (Thermo Scientific), according to Packer et al (1998) and Chong et al (2011). The acidic XOSs were eluted in 50% (v/v) acetonitrile acidified with 0.05% (v/v) trifluoroacetic acid, dried, and finally dissolved in 30 mL Milli-Q water.…”

“…As the neutral XOSs without MeGlcA substituents are less informative for structural fingerprinting, only the acidic XOSs were analyzed in this work. The atmospheric pressure matrix-assisted laser desorption/ionization-ion trap mass spectrometry analysis was carried out as previously described (Chong et al, 2011). Mass lists corresponding to acidic XOS mass peaks were extracted from Bruker's liquid chomatography/mass selective detector ion trap software 5.2, and calculation of percentage intensities for the selected mass peaks was as previously described (Chong et al, 2011).…”

“…The atmospheric pressure matrix-assisted laser desorption/ionization-ion trap mass spectrometry analysis was carried out as previously described (Chong et al, 2011). Mass lists corresponding to acidic XOS mass peaks were extracted from Bruker's liquid chomatography/mass selective detector ion trap software 5.2, and calculation of percentage intensities for the selected mass peaks was as previously described (Chong et al, 2011). The endo-1,4-b-D-xylanase liberated two series of acidic XOSs that comprised of GlcA (1→2)-linked XOS (GlcA-XOS) and MeGlcA (1→2)-linked XOS (MeGlcA-XOS) (Chong et al, 2011).…”

“…Mass lists corresponding to acidic XOS mass peaks were extracted from Bruker's liquid chomatography/mass selective detector ion trap software 5.2, and calculation of percentage intensities for the selected mass peaks was as previously described (Chong et al, 2011). The endo-1,4-b-D-xylanase liberated two series of acidic XOSs that comprised of GlcA (1→2)-linked XOS (GlcA-XOS) and MeGlcA (1→2)-linked XOS (MeGlcA-XOS) (Chong et al, 2011). Intensities in percentage of all the identified MeGlcA-XOS and GlcA-XOS mass spectrometry peaks were analyzed in principal components analysis with SIMCA-P+ 12.0.1 (Umetric) to reveal differences between the samples.…”