Structural Characterisation by ESI-MS of Feruloylated Arabino-oligosaccharides Synthesised by Chemoenzymatic Esterification

The chemoenzymatic synthesis of feruloylated arabino-oligosaccharides has neen achieved, using a feruloyl esterase type C from Sporotrichum themophile (StFaeC). The structure of the feruloyl products was comfirmed by ESI-MS

Functional Region Identification in Proteins by Accumulative-Quantitative Peptide Mapping Using RP-HPLC-MS

A new method was developed to identify regions in proteins from which peptides are derived with specific functional properties. This method is applicable for systems in which peptides of a hydrolyzed protein possess specific functional properties, but are too large to be sequenced directly and/or the peptide mixture is too complex to purify and characterize each peptide individually. In the present work, aggregating peptides obtained by proteolytic hydrolysis of soy glycinin were used as a case study. The aggregating peptides are isolated and subsequently further degraded with trypsin to result in peptides with a mas

Characterisation of 3-aminoquinoline-derivatised isomeric oligogalacturonic acid by travelling-wave ion mobility mass spectrometry

RATIONALE Mass spectrometry has become a useful technique for elucidating the chemical structures of oligosaccharides. The combined use of chromatography and mass spectrometry for the separation and identification of oligosaccharides has shown much progress in recent years. However, no powerful method has yet been developed to quickly identify isomeric oligosaccharides in complex mixtures. METHODS A rapid travelling-wave ion mobility mass spectrometry (TWIMS-MS) method was developed for the identification of various isomeric oligogalacturonic acids in mixtures and determined their structures, using 3-aminoquinoline (3-AQ) as a labelling agent. RESULTS TWIMS successfully distinguished isomeric oligogalacturonic acids of various degrees of polymerisation (DPs) and levels of methyl-esterification. After derivatisation by 3-AQ, isomeric oligosaccharides of galacturonic acid, with the DP ranging from 2 to 9 and the number of methyl esters ranging from 1 to 5, were identified by 3-AQ-TWIMS-MS. The isomeric oligosaccharides with varying sites of methyl ester substitution were identified by the post-fragmentation mode of TWIMS using 3-AQ labelling to obtain simplified mass spectra. CONCLUSIONS Using the 3-AQ-TWIMS-MS method, the precise distribution of methyl esters within the pectin molecule and isomeric oligogalacturonic acids after enzyme degradation was determined. Simplified product ion mass spectra and precise analysis of the isomers were achieved by labelling 3-AQ at the reducing end of the oligosaccharides. Series of methyl-esterified galacturonic acid oligomers have predictable drift times, depending on the precise position of the methyl ester

Delftse Archeologische Rapporten 116

Archeologisch opgraving vindplaats 1 Abtswoude (MD005) tbv de aanleg van de (ondergrondse) hoogspanningsverbinding Randstad 380kV Zuidring. Opdrachtgever TenneT TSO B

Een herwaardering van controllership

Most studies on plant‐soil feedback (PSF) and plant competition measure the feedback response at one moment only. However, PSFs and competition may both change over time, and how PSF and competition interact over time is unclear. We tested the temporal dynamics of PSF and interspecific competition for the forb Jacobaea vulgaris and the grass Holcus lanatus. We grew both species individually and in interspecific competition in soil that was first conditioned in the greenhouse by J. vulgaris, by H. lanatus or without plant growth. For a period of 11 weeks, we harvested plants twice a week and analysed the fungal and chemical composition of the different soils at the end of the first and second growth phase. During the second growth phase, when grown in isolation, both species produced more biomass in heterospecific conditioned soil than in conspecific conditioned soil. Young J. vulgaris exhibited a strong negative conspecific feedback, but this effect diminished over time and became neutral in older plants. In contrast, when grown in competition, the negative conspecific feedback of J. vulgaris exacerbated over time. Older H. lanatus plants benefited more from heterospecific conditioning when competing with J. vulgaris, then when grown isolated. Fungal community composition and soil chemistry differed significantly between soils but this was mainly driven by differences between plant‐conditioned and unconditioned soils. Remarkably, at the end of the second growth phase, fungal community composition was not explained by the legacy of the species that had been grown in the soil most recently, but still reflected the legacy of the first growth phase. We reexamined plant growth during a third growth phase. Biomass of J. vulgaris was still influenced by the treatments imposed during the first phase, while H. lanatus responded only to the plant growth treatments imposed during the second phase. Synthesis. Our study shows that the direction and magnitude of PSF depends on plant age and competition, and also on soil legacy effects of earlier plant growth. These results highlight the need to incorporate dynamic PSFs in research on plant populations and communities