TY  - JOUR
AU  - Duvnjak, Marija
AU  - Butorac, Ana
AU  - Kljak, Kristina
AU  - Nišavić, Marija
AU  - Cindrić, Mario
AU  - Grbeša, Darko
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10483
AB  - The starch availability and nutritional value of corn (Zea mays L.) are affected by zein proteins. The aim of the study was to see whether the proposed reduction of γ-zeins during the fermentation of silages is a result of either the enzymatic proteolytic activity or of the acidic environment, and how this reduction affects starch availability and degradability in high-moisture corn. A mass spectrometry (MS) technique was used to quantify the 16- and 27-kDa γ-zeins. Briefly, two-dimensional gel electrophoresis (2-DE) was used for γ-zein separation, followed by densitometry for protein quantification and matrix-assisted laser desorption ionization time-of-flight MS (MALDI-TOF/TOF) for protein identification. The results show that the reduction in γ-zeins induced by the ensiling led to a more pronounced starch availability and in vitro degradation, and this reduction was dependent on the type of proteolysis. More specifically, the results indicate that the reduction of γ-zeins in the ensiled corn was primarily driven by the enzymatic proteolysis. Furthermore, we demonstrated that 2-DE followed by densitometric quantification and the mass spectrometry analysis for protein identification can be used as a state-of-the-art method for γ-zein evaluation both in fresh and fermented/ensiled corn samples.
T2  - Fermentation
T1  - The Evaluation of γ-Zein Reduction Using Mass Spectrometry—The Influence of Proteolysis Type in Relation to Starch Degradability in Silages
VL  - 8
IS  - 10
SP  - 551
DO  - 10.3390/fermentation8100551
ER  - 

@article{
author = "Duvnjak, Marija and Butorac, Ana and Kljak, Kristina and Nišavić, Marija and Cindrić, Mario and Grbeša, Darko",
year = "2022",
abstract = "The starch availability and nutritional value of corn (Zea mays L.) are affected by zein proteins. The aim of the study was to see whether the proposed reduction of γ-zeins during the fermentation of silages is a result of either the enzymatic proteolytic activity or of the acidic environment, and how this reduction affects starch availability and degradability in high-moisture corn. A mass spectrometry (MS) technique was used to quantify the 16- and 27-kDa γ-zeins. Briefly, two-dimensional gel electrophoresis (2-DE) was used for γ-zein separation, followed by densitometry for protein quantification and matrix-assisted laser desorption ionization time-of-flight MS (MALDI-TOF/TOF) for protein identification. The results show that the reduction in γ-zeins induced by the ensiling led to a more pronounced starch availability and in vitro degradation, and this reduction was dependent on the type of proteolysis. More specifically, the results indicate that the reduction of γ-zeins in the ensiled corn was primarily driven by the enzymatic proteolysis. Furthermore, we demonstrated that 2-DE followed by densitometric quantification and the mass spectrometry analysis for protein identification can be used as a state-of-the-art method for γ-zein evaluation both in fresh and fermented/ensiled corn samples.",
journal = "Fermentation",
title = "The Evaluation of γ-Zein Reduction Using Mass Spectrometry—The Influence of Proteolysis Type in Relation to Starch Degradability in Silages",
volume = "8",
number = "10",
pages = "551",
doi = "10.3390/fermentation8100551"
}

Duvnjak, M., Butorac, A., Kljak, K., Nišavić, M., Cindrić, M.,& Grbeša, D.. (2022). The Evaluation of γ-Zein Reduction Using Mass Spectrometry—The Influence of Proteolysis Type in Relation to Starch Degradability in Silages. in Fermentation, 8(10), 551.
https://doi.org/10.3390/fermentation8100551

Duvnjak M, Butorac A, Kljak K, Nišavić M, Cindrić M, Grbeša D. The Evaluation of γ-Zein Reduction Using Mass Spectrometry—The Influence of Proteolysis Type in Relation to Starch Degradability in Silages. in Fermentation. 2022;8(10):551.
doi:10.3390/fermentation8100551 .

Duvnjak, Marija, Butorac, Ana, Kljak, Kristina, Nišavić, Marija, Cindrić, Mario, Grbeša, Darko, "The Evaluation of γ-Zein Reduction Using Mass Spectrometry—The Influence of Proteolysis Type in Relation to Starch Degradability in Silages" in Fermentation, 8, no. 10 (2022):551,
https://doi.org/10.3390/fermentation8100551 . .

TY  - JOUR
AU  - Nišavić, Marija
AU  - Hozić, Amela
AU  - Hameršak, Zdenko
AU  - Radić, Martina
AU  - Butorac, Ana
AU  - Duvnjak, Marija
AU  - Cindrić, Mario
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1552
AB  - Liquid chromatography coupled with electrospray ionization mass spectrometry (ESI-MS) is routinely used in proteomics research. Mass spectrometry-based peptide analysis is performed de facto in positive-ion mode, except for the analysis of some post-translationally modified peptides (e.g., phosphorylation and glycosylation). Collected mass spectrometry data after peptide negative ionization analysis is scarce, because of a lack of negatively charged amino acid side-chain residues that would enable efficient ionization (i.e., on average, every 10th amino acid residue is negatively charged). Also, several phenomena linked to negative ionization, such as corona discharge, arcing, and electrospray destabilization, because of the presence of polar mobile-phase solutions or acidic mobile-phase additives (e.g., formic or trifluoroacetic acid), reduce its use. Named phenomena influence microflow and nanoflow electrospray ionization (ESI) of peptides in a way that prevents the formation of negatively charged peptide ions. In this work, we have investigated the effects of post-column addition of isopropanol solutions of formaldehyde, 2,2-dimethylpropanal, ethyl methanoate, and 2-phenyl-2-oxoethanal as the negative-ion-mode mobile-phase modifiers for the analysis of peptides. According to the obtained data, all four modifiers exhibited significant enhancement of peptide negative ionization, while ethyl methanoate showed the best results. The proposed mechanism of action of the modifiers includes proton transfer reactions through oxonium ion formation. In this way, mobile phase protons are prevented from interfering with the process of negative ionization. To the best of our knowledge, this is the first study that describes the use and reaction mechanism of aforementioned modifiers for enhancement of peptide negative ionization.
T2  - Analytical Chemistry
T1  - High-Efficiency Microflow and Nanoflow Negative Electrospray Ionization of Peptides Induced by Gas-Phase Proton Transfer Reactions
VL  - 89
IS  - 9
SP  - 4847
EP  - 4854
DO  - 10.1021/acs.analchem.6b04466
ER  - 

@article{
author = "Nišavić, Marija and Hozić, Amela and Hameršak, Zdenko and Radić, Martina and Butorac, Ana and Duvnjak, Marija and Cindrić, Mario",
year = "2017",
abstract = "Liquid chromatography coupled with electrospray ionization mass spectrometry (ESI-MS) is routinely used in proteomics research. Mass spectrometry-based peptide analysis is performed de facto in positive-ion mode, except for the analysis of some post-translationally modified peptides (e.g., phosphorylation and glycosylation). Collected mass spectrometry data after peptide negative ionization analysis is scarce, because of a lack of negatively charged amino acid side-chain residues that would enable efficient ionization (i.e., on average, every 10th amino acid residue is negatively charged). Also, several phenomena linked to negative ionization, such as corona discharge, arcing, and electrospray destabilization, because of the presence of polar mobile-phase solutions or acidic mobile-phase additives (e.g., formic or trifluoroacetic acid), reduce its use. Named phenomena influence microflow and nanoflow electrospray ionization (ESI) of peptides in a way that prevents the formation of negatively charged peptide ions. In this work, we have investigated the effects of post-column addition of isopropanol solutions of formaldehyde, 2,2-dimethylpropanal, ethyl methanoate, and 2-phenyl-2-oxoethanal as the negative-ion-mode mobile-phase modifiers for the analysis of peptides. According to the obtained data, all four modifiers exhibited significant enhancement of peptide negative ionization, while ethyl methanoate showed the best results. The proposed mechanism of action of the modifiers includes proton transfer reactions through oxonium ion formation. In this way, mobile phase protons are prevented from interfering with the process of negative ionization. To the best of our knowledge, this is the first study that describes the use and reaction mechanism of aforementioned modifiers for enhancement of peptide negative ionization.",
journal = "Analytical Chemistry",
title = "High-Efficiency Microflow and Nanoflow Negative Electrospray Ionization of Peptides Induced by Gas-Phase Proton Transfer Reactions",
volume = "89",
number = "9",
pages = "4847-4854",
doi = "10.1021/acs.analchem.6b04466"
}

Nišavić, M., Hozić, A., Hameršak, Z., Radić, M., Butorac, A., Duvnjak, M.,& Cindrić, M.. (2017). High-Efficiency Microflow and Nanoflow Negative Electrospray Ionization of Peptides Induced by Gas-Phase Proton Transfer Reactions. in Analytical Chemistry, 89(9), 4847-4854.
https://doi.org/10.1021/acs.analchem.6b04466

Nišavić M, Hozić A, Hameršak Z, Radić M, Butorac A, Duvnjak M, Cindrić M. High-Efficiency Microflow and Nanoflow Negative Electrospray Ionization of Peptides Induced by Gas-Phase Proton Transfer Reactions. in Analytical Chemistry. 2017;89(9):4847-4854.
doi:10.1021/acs.analchem.6b04466 .

Nišavić, Marija, Hozić, Amela, Hameršak, Zdenko, Radić, Martina, Butorac, Ana, Duvnjak, Marija, Cindrić, Mario, "High-Efficiency Microflow and Nanoflow Negative Electrospray Ionization of Peptides Induced by Gas-Phase Proton Transfer Reactions" in Analytical Chemistry, 89, no. 9 (2017):4847-4854,
https://doi.org/10.1021/acs.analchem.6b04466 . .