@article{UhrWielandHomannetal.2016,
  author    = {Uhr, Linda and Wieland, Phillis and Homann, Thomas and Huschek, Gerd and Rawel, Harshadrai Manilal},
  title     = {Identification and LC-MS/MS-based analyses of technical enzymes in wheat flour and baked products},
  series = {European food research and technology : official organ of the EuCheMS, Division of Food Chemistry},
  volume    = {242},
  journal   = {European food research and technology : official organ of the EuCheMS, Division of Food Chemistry},
  publisher = {Springer},
  address   = {New York},
  issn      = {1438-2377},
  doi       = {10.1007/s00217-015-2536-5},
  pages     = {247 -- 257},
  year      = {2016},
  abstract  = {The use of technical enzymes in bakery industry is necessary for a consistent and good quality of baked products. Since the cultivation of cereals leads to low amounts of endogenous enzymes being present, a need of their commercial alternatives is becoming a routine process in order to meet the consumer quality demands. Targeted quantification proteomics-based methods are necessary for their detection to meet the regulatory criteria. Here, we initially report on the identification of Lipase FE-01, a lipase from fungus Thermomyces lanuginosus, as analyzed by SDS-PAGE, in-Gel digestion, and MALDI-TOF-MS. In further experiments, the focus of the study was directed toward an extensive use and optimization of in-solution enzymatic digestion in combination with LC-MS/MS techniques in identification of specific peptide markers and finally in utilization of the latter in delivering reproducible quantification data for several different technical enzymes (alpha-amylases, xylanase, and lipases from microbial origin) in complex matrices such as baked bread and wheat flour. Two digestion protocols (a fast option using thermocycler program and the well-established overnight method) were tested, and both of these can be successfully applied. The application of isotopically labeled analogs of the MRM targeted peptides as internal standards and the addition of an internal protein standard during the extraction/digestion experiment were compared to determine the optimal quantification algorithm of the recovered enzyme concentrations. Thus, a standardized sensitive LC-MS/MS method could be developed to determine technical enzymes as forthcoming ingredients in the prefabricated food formulations in concentrations lower than 10 ppm.},
  language  = {en}
}
@article{UhrBuchholzHomannetal.2014,
  author    = {Uhr, Linda and Buchholz, Tina and Homann, Thomas and Huschek, Gerd and Rawel, Harshadrai Manilal},
  title     = {Targeted proteomics-based analysis of technical enzymes from fungal origin in baked products},
  series = {Journal of cereal science},
  volume    = {60},
  journal   = {Journal of cereal science},
  number    = {2},
  publisher = {Elsevier},
  address   = {London},
  issn      = {0733-5210},
  doi       = {10.1016/j.jcs.2014.04.007},
  pages     = {440 -- 447},
  year      = {2014},
  abstract  = {The application of technical enzymes is a potential tool in modulating the dough and baking quality of cereal products. No endogenous amylases (alpha- and beta-forms) are present in mature wheat grains; they may be synthesized or activated during germination. Hence, microbial alpha-amylases are added to the dough, being resistant to the endogenous alpha-amylase/trypsin inhibitors. Here, we report on the initial identification of two technical enzymes from a commercial sample based on an in-gel tryptic digestion coupled with MALDI-MS analysis. The primary component of the protein fraction with 51.3 kDa was alpha-amylase from Aspergillus species. A second major protein with 24.8 kDa was identified as endo-1,4-xylanase from Thermomyces lanuginosus. In the following experimental work up, a targeted proteomics approach utilizing the combination of specific proteolytic digestion of the added amylase and xylanase in wheat flour, dough or baked products, solid phase extraction of released peptides and their detection using LC-MS/MS was optimized. The targeted (MRM) MS/MS peptide signals showed that the peptide "ALSSALHER" (MW = 983) originating from amylase and "GWNPGLNAR" (MW = 983) from xylanase can be used to identify the corresponding technical enzymes added. Consequently, locally available baked products were tested and found to contain these enzymes as supplementary ingredients. (C) 2014 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{TchewonpiSaguLandgraeberHenkeletal.2021,
  author    = {Tchewonpi Sagu, Sorel and Landgr{\"a}ber, Eva and Henkel, Ina M. and Huschek, Gerd and Homann, Thomas and Bußler, Sara and Schl{\"u}ter, Oliver K. and Rawel, Harshadrai Manilal},
  title     = {Effect of cereal α-amylase/trypsin inhibitors on developmental characteristics and abundance of digestive enzymes of mealworm larvae (Tenebrio molitor L.)},
  series = {Insects},
  volume    = {12},
  journal   = {Insects},
  number    = {5},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2075-4450},
  doi       = {10.3390/insects12050454},
  pages     = {16},
  year      = {2021},
  abstract  = {The objective of this work was to investigate the potential effect of cereal α-amylase/trypsin inhibitors (ATIs) on growth parameters and selective digestive enzymes of Tenebrio molitor L. larvae. The approach consisted of feeding the larvae with wheat, sorghum and rice meals containing different levels and composition of α-amylase/trypsin inhibitors. The developmental and biochemical characteristics of the larvae were assessed over feeding periods of 5 h, 5 days and 10 days, and the relative abundance of α-amylase and selected proteases in larvae were determined using liquid chromatography tandem mass spectrometry. Overall, weight gains ranged from 21\% to 42\% after five days of feeding. The larval death rate significantly increased in all groups after 10 days of feeding (p < 0.05), whereas the pupation rate was about 25\% among larvae fed with rice (Oryza sativa L.) and Siyazan/Esperya wheat meals, and only 8\% and 14\% among those fed with Damougari and S35 sorghum meals. As determined using the Lowry method, the protein contents of the sodium phosphate extracts ranged from 7.80 ± 0.09 to 9.42 ± 0.19 mg/mL and those of the ammonium bicarbonate/urea reached 19.78 ± 0.16 to 37.47 ± 1.38 mg/mL. The total protein contents of the larvae according to the Kjeldahl method ranged from 44.0 and 49.9 g/100 g. The relative abundance of α-amylase, CLIP domain-containing serine protease, modular serine protease zymogen and C1 family cathepsin significantly decreased in the larvae, whereas dipeptidylpeptidase I and chymotrypsin increased within the first hours after feeding (p < 0.05). Trypsin content was found to be constant independently of time or feed material. Finally, based on the results we obtained, it was difficult to substantively draw conclusions on the likely effects of meal ATI composition on larval developmental characteristics, but their effects on the digestive enzyme expression remain relevant.},
  language  = {en}
}
@misc{TchewonpiSaguLandgraeberHenkeletal.2021,
  author    = {Tchewonpi Sagu, Sorel and Landgr{\"a}ber, Eva and Henkel, Ina M. and Huschek, Gerd and Homann, Thomas and Bußler, Sara and Schl{\"u}ter, Oliver K. and Rawel, Harshadrai Manilal},
  title     = {Effect of cereal α-amylase/trypsin inhibitors on developmental characteristics and abundance of digestive enzymes of mealworm larvae (Tenebrio molitor L.)},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {5},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-52092},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-520924},
  pages     = {18},
  year      = {2021},
  abstract  = {The objective of this work was to investigate the potential effect of cereal α-amylase/trypsin inhibitors (ATIs) on growth parameters and selective digestive enzymes of Tenebrio molitor L. larvae. The approach consisted of feeding the larvae with wheat, sorghum and rice meals containing different levels and composition of α-amylase/trypsin inhibitors. The developmental and biochemical characteristics of the larvae were assessed over feeding periods of 5 h, 5 days and 10 days, and the relative abundance of α-amylase and selected proteases in larvae were determined using liquid chromatography tandem mass spectrometry. Overall, weight gains ranged from 21\% to 42\% after five days of feeding. The larval death rate significantly increased in all groups after 10 days of feeding (p < 0.05), whereas the pupation rate was about 25\% among larvae fed with rice (Oryza sativa L.) and Siyazan/Esperya wheat meals, and only 8\% and 14\% among those fed with Damougari and S35 sorghum meals. As determined using the Lowry method, the protein contents of the sodium phosphate extracts ranged from 7.80 ± 0.09 to 9.42 ± 0.19 mg/mL and those of the ammonium bicarbonate/urea reached 19.78 ± 0.16 to 37.47 ± 1.38 mg/mL. The total protein contents of the larvae according to the Kjeldahl method ranged from 44.0 and 49.9 g/100 g. The relative abundance of α-amylase, CLIP domain-containing serine protease, modular serine protease zymogen and C1 family cathepsin significantly decreased in the larvae, whereas dipeptidylpeptidase I and chymotrypsin increased within the first hours after feeding (p < 0.05). Trypsin content was found to be constant independently of time or feed material. Finally, based on the results we obtained, it was difficult to substantively draw conclusions on the likely effects of meal ATI composition on larval developmental characteristics, but their effects on the digestive enzyme expression remain relevant.},
  language  = {en}
}
@misc{TchewonpiSaguHuschekHomannetal.2021,
  author    = {Tchewonpi Sagu, Sorel and Huschek, Gerd and Homann, Thomas and Rawel, Harshadrai Manilal},
  title     = {Effect of sample preparation on the detection and quantification of selected nuts allergenic proteins by LC-MS/MS},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {15},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-52187},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-521871},
  pages     = {16},
  year      = {2021},
  abstract  = {The detection and quantification of nut allergens remains a major challenge. The liquid chroma-tography tandem mass spectrometry (LC-MS/MS) is emerging as one of the most widely used methods, but sample preparation prior to the analysis is still a key issue. The objective of this work was to establish optimized protocols for extraction, tryptic digestion and LC-MS analysis of almond, cashew, hazelnut, peanut, pistachio and walnut samples. Ammonium bicar-bonate/urea extraction (Ambi/urea), SDS buffer extraction (SDS), polyvinylpolypyrroli-done (PVPP) extraction, trichloroacetic acid/acetone extraction (TCA/acetone) and chloro-form/methanol/sodium chloride precipitation (CM/NaCl) as well as the performances of con-ventional tryptic digestion and microwave-assisted breakdown were investigated. Overall, the protein extraction yields ranged from 14.9 ± 0.5 (almond extract from CM/NaCl) to 76.5 ± 1.3\% (hazelnut extract from Ambi/urea). Electrophoretic profiling showed that the SDS extraction method clearly presented a high amount of extracted proteins in the range of 0-15 kDa, 15-35 kDa, 35-70 kDa and 70-250 kDa compared to the other methods. The linearity of the LC-MS methods in the range of 0 to 0.4 µg equivalent defatted nut flour was assessed and recovery of internal standards GWGG and DPLNV(d8)LKPR ranged from 80 to 120\%. The identified bi-omarkers peptides were used to relatively quantifier selected allergenic protein form the inves-tigated nut samples. Considering the overall results, it can be concluded that SDS buffer allows a better protein extraction from almond, peanut and walnut samples while PVPP buffer is more appropriate for cashew, pistachio and hazelnut samples. It was also found that conventional overnight digestion is indicated for cashew, pistachio and hazelnut samples, while microwave assisted tryptic digestion is recommended for almond, hazelnut and peanut extracts.},
  language  = {en}
}
@article{SilvaOliveiraCostaTchewonpietal.2021,
  author    = {Silva, Bibiana and Oliveira Costa, Ana Carolina and Tchewonpi, Sorel Sagu and B{\"o}nick, Josephine and Huschek, Gerd and Gonzaga, Luciano Valdemiro and Fett, Roseane and Baldermann, Susanne and Rawel, Harshadrai Manilal},
  title     = {Comparative quantification and differentiation of bracatinga (Mimosa scabrella Bentham) honeydew honey proteins using targeted peptide markers identified by high-resolution mass spectrometry},
  series = {Food research international},
  volume    = {141},
  journal   = {Food research international},
  publisher = {Elsevier},
  address   = {New York, NY [u.a.]},
  issn      = {0963-9969},
  doi       = {10.1016/j.foodres.2020.109991},
  pages     = {10},
  year      = {2021},
  abstract  = {Honey traceability is an important topic, especially for honeydew honeys, due to the increased incidence of adulteration. This study aimed to establish specific markers to quantify proteins in honey. A proteomics strategy to identify marker peptides from bracatinga honeydew honey was therefore developed. The proteomics approach was based on initial untargeted identification of honey proteins and peptides by LC-ESI-Triple-TOF-MS/MS, which identified the major royal jelly proteins (MRJP) presence. Afterwards, the peptides were selected by the in silico digestion. The marker peptides were quantified by the developed targeted LC-QqQ-MS/MS method, which provided good linearity and specificity, besides recoveries between 92 and 100\% to quantify peptides from bracatinga honeydew honey. The uniqueness and high response in mass spectrometry were backed by further complementary protein analysis (SDS-PAGE). The selected marker peptides EALPHVPIFDR (MRJP 1), ILGANVK (MRJP 2), TFVTIER (MRJP 3), QNIDVVAR (MRJP 4), FINNDYNFNEVNFR (MRJP 5) and LLQPYPDWSWTK (MRJP 7), quantified by LC-QqQ-MS/MS, highlighted that the content of QNIDVVAR from MRJP 4 could be used to differentiate bracatinga honeydew honey from floral honeys (p < 0.05) as a potential marker for its authentication. Finally, principal components analysis highlighted the QNIDVVAR content as a good descriptor of the analyzed bracatinga honeydew honey samples.},
  language  = {en}
}
@article{SaguTchewonpiZimmermannLandgraeberetal.2020,
  author    = {Sagu Tchewonpi, Sorel and Zimmermann, Lynn and Landgr{\"a}ber, Eva and Homann, Thomas and Huschek, Gerd and {\"O}zpinar, Haydar and Schweigert, Florian J. and Rawel, Harshadrai Manilal},
  title     = {Comprehensive Characterization and Relative Quantification of α-Amylase/Trypsin Inhibitors from Wheat Cultivars by Targeted HPLC-MS/MS},
  series = {Foods},
  volume    = {9},
  journal   = {Foods},
  number    = {10},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2304-8158},
  doi       = {10.3390/foods9101448},
  pages     = {25},
  year      = {2020},
  abstract  = {The α-amylase/trypsin inhibitors (ATIs) are discussed as being responsible for non-celiac wheat sensitivity (NCWS), besides being known as allergenic components for baker's asthma. Different approaches for characterization and quantification including proteomics-based methods for wheat ATIs have been documented. In these studies generally the major ATIs have been addressed. The challenge of current study was then to develop a more comprehensive workflow encompassing all reviewed wheat-ATI entries in UniProt database. To substantially test proof of concept, 46 German and Turkish wheat samples were used. Two extractions systems based on chloroform/methanol mixture (CM) and under buffered denaturing conditions were evaluated. Three aspects were optimized, tryptic digestion, chromatographic separation, and targeted tandem mass spectrometric analysis (HPLC-MS/MS). Preliminary characterization with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) documented the purity of the extracted ATIs with CM mixture and the amylase (60-80\%)/trypsin (10-20\%) inhibition demonstrated the bifunctional activity of ATIs. Thirteen (individual/common) biomarkers were established. Major ATIs (7-34\%) were differently represented in samples. Finally, to our knowledge, the proposed HPLC-MS/MS method allowed for the first time so far the analysis of all 14 reviewed wheat ATI entries reported.},
  language  = {en}
}
@misc{SaguTchewonpiZimmermannLandgraeberetal.2020,
  author    = {Sagu Tchewonpi, Sorel and Zimmermann, Lynn and Landgr{\"a}ber, Eva and Homann, Thomas and Huschek, Gerd and {\"O}zpinar, Haydar and Schweigert, Florian J. and Rawel, Harshadrai Manilal},
  title     = {Comprehensive Characterization and Relative Quantification of α-Amylase/Trypsin Inhibitors from Wheat Cultivars by Targeted HPLC-MS/MS},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1028},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-48611},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-486118},
  pages     = {27},
  year      = {2020},
  abstract  = {The α-amylase/trypsin inhibitors (ATIs) are discussed as being responsible for non-celiac wheat sensitivity (NCWS), besides being known as allergenic components for baker's asthma. Different approaches for characterization and quantification including proteomics-based methods for wheat ATIs have been documented. In these studies generally the major ATIs have been addressed. The challenge of current study was then to develop a more comprehensive workflow encompassing all reviewed wheat-ATI entries in UniProt database. To substantially test proof of concept, 46 German and Turkish wheat samples were used. Two extractions systems based on chloroform/methanol mixture (CM) and under buffered denaturing conditions were evaluated. Three aspects were optimized, tryptic digestion, chromatographic separation, and targeted tandem mass spectrometric analysis (HPLC-MS/MS). Preliminary characterization with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) documented the purity of the extracted ATIs with CM mixture and the amylase (60-80\%)/trypsin (10-20\%) inhibition demonstrated the bifunctional activity of ATIs. Thirteen (individual/common) biomarkers were established. Major ATIs (7-34\%) were differently represented in samples. Finally, to our knowledge, the proposed HPLC-MS/MS method allowed for the first time so far the analysis of all 14 reviewed wheat ATI entries reported.},
  language  = {en}
}
@misc{SaguTchewonpiLandgraeberRackiewiczetal.2020,
  author    = {Sagu Tchewonpi, Sorel and Landgr{\"a}ber, Eva and Rackiewicz, Michal and Huschek, Gerd and Rawel, Harshadrai Manilal},
  title     = {Relative Abundance of Alpha-Amylase/Trypsin Inhibitors in Selected Sorghum Cultivars},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1068},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-48809},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-488096},
  pages     = {21},
  year      = {2020},
  abstract  = {Sorghum is of growing interest and considered as a safe food for wheat related disorders. Besides the gluten, α-amylase/trypsin-inhibitors (ATIs) have been identified as probable candidates for these disorders. Several studies focused on wheat-ATIs although there is still a lack of data referring to the relative abundance of sorghum-ATIs. The objective of this work was therefore to contribute to the characterization of sorghum ATI profiles by targeted proteomics tools. Fifteen sorghum cultivars from different regions were investigated with raw proteins ranging from 7.9 to 17.0 g/100 g. Ammonium bicarbonate buffer in combination with urea was applied for protein extraction, with concentration from 0.588 ± 0.047 to 4.140 ± 0.066 mg/mL. Corresponding electrophoresis data showed different protein profiles. UniProtKB data base research reveals two sorghum ATIs, P81367 and P81368; both reviewed and a targeted LC-MS/MS method was developed to analyze these. Quantifier peptides ELAAVPSR (P81367) and TYMVR (P81368) were identified and retained as biomarkers for relative quantification. Different reducing and alkylating agents were assessed and combination of tris (2 carboxyethyl) phosphine/iodoacetamide gave the best response. Linearity was demonstrated for the quantifier peptides with standard recovery between 92.2 and 107.6\%. Nine sorghum cultivars presented up to 60 times lower ATI contents as compared to wheat samples. This data suggests that sorghum can effectively be considered as a good alternative to wheat.},
  language  = {en}
}
@article{SaguTchewonpiLandgraeberRackiewiczetal.2020,
  author    = {Sagu Tchewonpi, Sorel and Landgr{\"a}ber, Eva and Rackiewicz, Michal and Huschek, Gerd and Rawel, Harshadrai Manilal},
  title     = {Relative Abundance of Alpha-Amylase/Trypsin Inhibitors in Selected Sorghum Cultivars},
  series = {Molecules},
  volume    = {25},
  journal   = {Molecules},
  number    = {24},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1420-3049},
  doi       = {10.3390/molecules25245982},
  pages     = {19},
  year      = {2020},
  abstract  = {Sorghum is of growing interest and considered as a safe food for wheat related disorders. Besides the gluten, α-amylase/trypsin-inhibitors (ATIs) have been identified as probable candidates for these disorders. Several studies focused on wheat-ATIs although there is still a lack of data referring to the relative abundance of sorghum-ATIs. The objective of this work was therefore to contribute to the characterization of sorghum ATI profiles by targeted proteomics tools. Fifteen sorghum cultivars from different regions were investigated with raw proteins ranging from 7.9 to 17.0 g/100 g. Ammonium bicarbonate buffer in combination with urea was applied for protein extraction, with concentration from 0.588 ± 0.047 to 4.140 ± 0.066 mg/mL. Corresponding electrophoresis data showed different protein profiles. UniProtKB data base research reveals two sorghum ATIs, P81367 and P81368; both reviewed and a targeted LC-MS/MS method was developed to analyze these. Quantifier peptides ELAAVPSR (P81367) and TYMVR (P81368) were identified and retained as biomarkers for relative quantification. Different reducing and alkylating agents were assessed and combination of tris (2 carboxyethyl) phosphine/iodoacetamide gave the best response. Linearity was demonstrated for the quantifier peptides with standard recovery between 92.2 and 107.6\%. Nine sorghum cultivars presented up to 60 times lower ATI contents as compared to wheat samples. This data suggests that sorghum can effectively be considered as a good alternative to wheat.},
  language  = {en}
}