[4] Identification of posttranslationally modified amino acids in proteins by mass spectrometry

Author(s):  
Steven A. Carr ◽  
Klaus Biemann
2018 ◽  
Vol 69 (10) ◽  
pp. 2794-2798
Author(s):  
Alina Diana Panainte ◽  
Ionela Daniela Morariu ◽  
Nela Bibire ◽  
Madalina Vieriu ◽  
Gladiola Tantaru ◽  
...  

A peptidic hydrolysate has been obtained through hydrolysis of bovine hemoglobin using pepsin. The fractioning of the hydrolysate was performed on a column packed with CM-Sepharose Fast Flow. The hydrolysate and each fraction was filtered and then injected into a HPLC system equipped with a Vydak C4 reverse phase column (0.46 x 25 cm), suitable for the chromatographic separation of large peptides with 20 to 30 amino acids. The detection was done using mass spectrometry, and the retention time, size and distribution of the peptides were determined.


Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 120 ◽  
Author(s):  
Jiuliang Xu ◽  
Liangquan Wu ◽  
Bingxin Tong ◽  
Jiaxu Yin ◽  
Zican Huang ◽  
...  

Oolong tea, one of the most famous tea beverages in China, contains specialized metabolites contributing to rich flavors and human health. Accumulation patterns of such metabolites and underlying regulatory mechanisms significantly vary under different growth conditions. To optimize quality and yield while minimizing environmental effects, three treatments were designed in this study: Conventional fertilization, optimized fertilization, and optimized fertilization supplemented with magnesium (Mg). We investigated the yield, taste quality, primary and secondary metabolites of oolong tea, and found that a substantial reduction in chemical fertilizers (nutrient optimization by reducing 43% N, 58% P2O5 and 55% K2O) did not affect the tea yield in this study. Interestingly, Mg fertilization is an important factor influencing amino acid and sugar accumulation in oolong tea, resulting in higher concentrations of total free amino acids and a lower ratio of tea polyphenols (TP) to free amino acids (FAA). Gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) and liquid chromatography-high resolution mass spectrometry (LC-HRMS) combined multivariate analyses revealed distinct features of metabolite accumulation in leaves of three different treatments, as indicated by 34 differentially accumulated characteristic compounds. The levels of serine, aspartic acid, isoleucine, phenylalanine, theanine, and proline were reduced by fertilizer optimization and increased by Mg supplementation. Mg particularly promoted theanine accumulation favoring a stronger umami taste of oolong tea, while decreasing astringency and bitter metabolites. Thus, Mg application paves a new path for tea quality improvement in Southern China where Mg deficiency in the soil is a frequent limiting factor for crop production.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Jianhua Cao ◽  
Benjamin Balluff ◽  
Martijn Arts ◽  
Ludwig J. Dubois ◽  
Luc J. C. van Loon ◽  
...  

Abstract Background Metabolic reprogramming is a common phenomenon in tumorigenesis and tumor progression. Amino acids are important mediators in cancer metabolism, and their kinetics in tumor tissue are far from being understood completely. Mass spectrometry imaging is capable to spatiotemporally trace important endogenous metabolites in biological tissue specimens. In this research, we studied L-[ring-13C6]-labeled phenylalanine and tyrosine kinetics in a human non-small cell lung carcinoma (NSCLC) xenografted mouse model using matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry imaging (MALDI-FTICR-MSI). Methods We investigated the L-[ring-13C6]-Phenylalanine (13C6-Phe) and L-[ring-13C6]-Tyrosine (13C6-Tyr) kinetics at 10 min (n = 4), 30 min (n = 3), and 60 min (n = 4) after tracer injection and sham-treated group (n = 3) at 10 min in mouse-xenograft lung tumor tissues by MALDI-FTICR-MSI. Results The dynamic changes in the spatial distributions of 19 out of 20 standard amino acids are observed in the tumor tissue. The highest abundance of 13C6-Phe was detected in tumor tissue at 10 min after tracer injection and decreased progressively over time. The overall enrichment of 13C6-Tyr showed a delayed temporal trend compared to 13C6-Phe in tumor caused by the Phe-to-Tyr conversion process. Specifically, 13C6-Phe and 13C6-Tyr showed higher abundances in viable tumor regions compared to non-viable regions. Conclusions We demonstrated the spatiotemporal intra-tumoral distribution of the essential aromatic amino acid 13C6-Phe and its de-novo synthesized metabolite 13C6-Tyr by MALDI-FTICR-MSI. Our results explore for the first time local phenylalanine metabolism in the context of cancer tissue morphology. This opens a new way to understand amino acid metabolism within the tumor and its microenvironment.


2021 ◽  
Vol 11 (11) ◽  
pp. 5112
Author(s):  
Julia Vega ◽  
Geniane Schneider ◽  
Bruna R. Moreira ◽  
Carolina Herrera ◽  
José Bonomi-Barufi ◽  
...  

Macroalgae belong to a diverse group of organisms that could be exploited for biomolecule application. Among the biocompounds found in this group, mycosporine-like amino acids (MAAs) are highlighted mainly due to their photoprotection, antioxidant properties, and high photo and thermo-stability, which are attractive characteristics for the development of cosmeceutical products. Therefore, here we revise published data about MAAs, including their biosynthesis, biomass production, extraction, characterization, identification, purification, and bioactivities. MAAs can be found in many algae species, but the highest concentrations are found in red macroalgae, mainly in the order Bangiales, as Porphyra spp. In addition to the species, the content of MAAs can vary depending on environmental factors, of which solar radiation and nitrogen availability are the most influential. MAAs can confer photoprotection due to their capacity to absorb ultraviolet radiation or reduce the impact of free radicals on cells, among other properties. To extract these compounds, different approaches can be used. The efficiency of these methods can be evaluated with characterization and identification using high performance liquid chromatography (HPLC), associated with other apparatus such as mass spectrometry (MS) and nuclear magnetic resonance (NMR). Therefore, the data presented in this review allow a broad comprehension of MAAs and show perspectives for their inclusion in cosmeceutical products.


2015 ◽  
Vol 7 (18) ◽  
pp. 7574-7581 ◽  
Author(s):  
Magdalena M. Dziągwa-Becker ◽  
Jose M. Marin Ramos ◽  
Jakub K. Topolski ◽  
Wiesław A. Oleszek

Free amino acid determination in plants by LC-MS/MS.


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