•Phosphoryl group has enhancement effect on MS-based oligosaccharide analysis.•4-(diphenylphosphinyl)-benzeneamine (4-DPPBA), as a novel reagent for oligosaccharides non-reductive amination derivatization, can be used for oligosaccharide analysis by mass spectrometry.•Without the tedious purification process, 4-DPPBA shows some intrinsic advantages, such as high derivatization rate, signal intensity, S/N ratio and the changeless fragment pattern between derivative and non-derivative oligosaccharide chains.Analysis of native oligosaccharides by MS has been a challenge due in part to their limited ionization capacity. To circumvent the problem, oligosaccharides may be chemically derivatized to improve their ionization efficiency. Here, a phosphorus-containing aniline derivative, 4-(diphenylphosphinyl)-benzeneamine (4-DPPBA) was used as a reagent for oligosaccharides non-reductive amination derivatization. In general, without the tedious purification process, a significant increase about 5-fold in the mass signal intensities and 4-fold in S/N ratio were obtained. The derivatization rate is above 98% under the optimized reaction conditions. Compared with aniline, 4-DPPBA shows some merits, such as high derivatization rate, signal intensity, S/N ratio and the changeless fragment pattern between derivative and non-derivative oligosaccharide chains. Based on the advantages, 4-DPPBA is of great potential to be one kind of oligosaccharides derivatization reagent with high performance and widely used in the analysis of oligosaccharides.Download high-res image (102KB)Download full-size image

The identification of carbohydrate isomers, including mono units, linkage positions and anomeric configurations, remains an arduous subject. In this study, the natural amino acid leucine (Leu) was found to specifically interact with cellobiose (Cello) to form a series of potassium adducts as [Cello + Leu + K]+, [Cello + 2Leu + K]+, and [2Cello + Leu + K]+ in the gas phase using mass spectrometry. By using CID-MS/MS, these complexes produced specific fragmentation patterns from the sugar backbone cleavage instead of non-covalent interactions. Moreover, their fragment distributions were dependent on the ratios of Cello-to-Leu in the complexes and the fragmentation pathways of potassium-cationized disaccharides (Dis) were remarkably changed with leucine binding. It should be pointed out that the ternary complex [2Cello + AA + K]+ was unique for leucine among all the twenty natural amino acids. The [2Dis + Leu + K]+ complex produced the most informative fragments by tandem mass spectrometry, which was successfully applied for rapid and efficient discrimination of twelve glucose-containing disaccharide isomers in combination with statistical analyses including PCA and OPLS-DA. The methodology developed here not only provides a novel analytical approach for the differentiation of disaccharide isomers, but also brings new sight towards the interactions of amino acids with disaccharides.

•MS technique was employed to dissect the intrinsic structure feature of sucrose.•Sucrose has the most labile glycosidic bond among sucrose isomers.•Sucrose has the most stable integral structure among sucrose isomers.•K+ is a better co-transporter for sucrose based on the MS results.•The above results are the new explanation for the nature selection of sucrose.Sucrose is the carbon skeletons and energy vector for plants, which is important for plants growth. Among thousands of disaccharides in Nature, why chose sucrose for plants? In this paper, we analyzed the intrinsic structural characteristics of four sucrose isomers with different glycosidic linkage by mass spectrometry (MS) technique. Our results show that sucrose has the most labile glycosidic bond compared with other three isomers, which is helpful for releasing glucose and fructose unit. Besides, sucrose has the most stable integral structure, which is hard to dehydrate and degrade into fragments through losing one or three even four-carbon units, just as its three isomers. In other words, sucrose is more easily holds an integral structure during the transport process, whenever it is necessary, and sucrose can be cleaved into glucose and fructose easily. Besides, we also investigate the internal relationship of sucrose with K+ by tandem mass spectrometry and viscosity measurement. The related results have shown that the K+ can stabilize sucrose to a greater extent than the Na+. Furthermore, under the same conditions, K+ ions reduce the viscosity of sucrose–water system much more than Na+. These results suggest that K+ is a better co-transporter for sucrose.Of course, the transport of sucrose in plants is a very complicated process, which is involved in many proteins. This paper directly accounts for the basic structure feature of sucrose, and the results discovered could provide the novel insight for the answer why Nature chose sucrose for plants.

According to previous literature, pYEEI and AcpYEEI also have high affinity with the SH2 domain specifically. However, up to now, few researches pay attention to the interaction difference between these two phosphopeptides which is caused by the N-terminal acetylation. In this paper, the competitive interaction between the SH2 domain and phosphopeptides (AcpYEEI and pYEEI) was investigated by native ESI ion trap mass spectrometry combined theoretical calculations. It was found that N-terminal acetylation of pYEEI strengthens the interaction with the SH2 domain. Through theoretical calculations, the binding affinity, Ka of AcpYEEI is approximately 91 times larger than Ka of pYEEI. The possible enhancement mechanism was proposed here.

A novel and efficient Cs2CO3-promoted phosphorylation or phosphinylation of various 1,1-dibromo-1-alkenes with readily available trialkyl phosphites, ethyl diphenylphosphinite, or diethyl phenylphosphonite has been developed under metal-free conditions, providing a practical and powerful tool for one-pot synthesis of valuable alkynylphosphonates, -phosphinates, and -phosphine oxides in good to excellent yields.