| 1. |
- Arrigoni, Giorgio, et al.
(författare)
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Chemical derivatization of phosphoserine and phosphothreonine containing peptides to increase sensitivity for MALDI-based analysis and for selectivity of MS/MS analysis
- 2006
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Ingår i: Proteomics. - : Wiley. - 1615-9861 .- 1615-9853. ; 6:3, s. 757-766
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Tidskriftsartikel (refereegranskat)abstract
- Protein phosphorylation is one of the most important and common ways of regulating protein function in cells. However, phosphopeptides are difficult to analyse, ionising poorly under standard MALDI conditions. Several methods have been developed to deal with the low sensitivity and specificity of phosphopeptide analysis. Here, we show an approach using a simple one-step beta-elimination/Michael addition reaction for the derivatization of phosphoserine and phosphothreonine. The substitution of the negatively charged phosphate group by a positively charged S-ethylpyridyl group greatly improves the ionisation of the modified peptides, especially in MALDI MS, increasing the sensitivity of the analysis. The modification allows the formation of a unique fragment ion at m/z 106 under mild collisional activation conditions, which can be used for parent (precursor) ion scanning in order to improve both the sensitivity and the selectivity of the analysis. The optimisation of the approach is described for a standard model peptide and protein and then applied to phosphorylation analysis in two biologically derived proteins purified from different experimental systems.
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| 2. |
- Bohn, T., et al.
(författare)
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Mind the gap - deficits in our knowledge of aspects impacting bioavailability of phytochemicals and their metabolites - a position paper focusing on carotenoids and polyphenols
- 2015
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Ingår i: Molecular Nutrition and Food Research. - : Wiley. - 1613-4133 .- 1613-4125. ; 59:7, s. 1307-13231-17-1323
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Forskningsöversikt (refereegranskat)abstract
- Various secondary plant metabolites or phytochemicals, including polyphenols and carotenoids, have been associated with a variety of health benefits, such as reduced incidence of type 2 diabetes, cardiovascular diseases, and several types of cancer, most likely due to their involvement in ameliorating inflammatory and oxidative stress. However, discrepancies exist between their putative effects when comparing observational and intervention studies, especially when using pure compounds. These discrepancies may in part be explained by differences in intake levels and their bioavailability. Prior to exerting their bioactivity, these compounds must be made bioavailable, and considerable differences may arise due to their their matrix release, changes during digestion, uptake, metabolism, and biodistribution, even before considering dose and host related factors. Though many insights have been gained on factors affecting secondary plant metabolite bioavailability, many gaps still exist in our knowledge. In this position paper, we highlight several major gaps in our understanding of phytochemical bioavailability, including effects of food processing, changes during digestion, involvement of cellular transporters in influx/efflux through the gastrointestinal epithelium, changes during colonic fermentation, and their phase I and phase II metabolism following absorption.
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