Nutritional and Metabolic Aspects of Protein Modification During Food Processing

Transglutaminases (TGases) are a class of enzyme widely spread in nature, and observed in plants, microorganisms, vertebrates and invertebrates. This enzyme catalyzes post-translational protein modification, by acyl transfer reactions, deamidation and crosslinking (polymerisation). There is a large interest for TGases functions, in particular for human TGases and their involvement in physiopathological processes. In bacteria, TGases appear largely present, although the function of this enzyme is still unknown. Microbial TGases (MTG, or MTGase) are of extreme interest, in particular MTGase from Streptomyces mobaraensis, used in biopolymers industry, in cosmetics production, in wool textiles, and in the food processing. We present the results of bioinformatics analysis on MTGases sequences, based on database searching, sequence comparisons and alignments, phylogenetic tree constructions, with the aim of improving the knowledge of MTGases, in the perspective of investigating by protein modelling and simulations techniques the functional features.

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Food Protein Sterylation: Chemical Reactions between Reactive Amino Acids and Sterol Oxidation Products under Food Processing Conditions

Foods ◽

10.3390/foods9121882 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1882

Author(s):

Franks Kamgang Nzekoue ◽

Thomas Henle ◽

Giovanni Caprioli ◽

Gianni Sagratini ◽

Michael Hellwig

Keyword(s):

Mass Spectrometry ◽

Amino Acids ◽

Food Processing ◽

Protein Modification ◽

Unsaturated Fatty Acids ◽

Oxidation Products ◽

Charge Ratio ◽

Array Detector ◽

Food Protein ◽

Secondary Products

Sterols, especially cholesterol and phytosterols, are important components of food lipids. During food processing, such as heating, sterols, like unsaturated fatty acids, can be oxidized. Protein modification by secondary products of lipid peroxidation has recently been demonstrated in food through a process called lipation. Similarly, this study was performed to assess, for the first time, the possibility of reactions between food proteins and sterol oxidation products in conditions relevant for food processing. Therefore, reaction models consisting of oxysterol (cholesterol 5α,6α-epoxide) and reactive amino acids (arginine, lysine, and methionine) were incubated in various conditions of concentration (0–8 mM), time (0–120 min), and temperature (30–180 °C). The identification of lysine adducts through thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) with a diode array detector (DAD), and electrospray ionization (ESI) mass spectrometry (MS) evidenced a reaction with lysine. Moreover, the HPLC-ESI with tandem mass spectrometry (MS/MS) analyses allowed observation of the compound, whose mass to charge ratio m/z 710.5 and fragmentation patterns corresponded to the reaction product [M + H]+ between cholesterol-5α,6α-epoxide and the ε-amino-group of Nα-benzoylglycyl-l-lysine. Moreover, kinetic studies between Nα-benzoylglycyl-l-lysine as a model for protein-bound lysine and cholesterol 5α,6α-epoxide were performed, showing that the formation of lysine adducts strongly increases with time, temperature, and oxysterol level. This preliminary study suggests that in conditions commonly reached during food processing, sterol oxidation products could react covalently with protein-bound lysine, causing protein modifications.

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Evolutionary relationships of microbial transglutaminases

10.7287/peerj.preprints.3320 ◽

2017 ◽

Author(s):

Deborah Giordano ◽

Angelo Facchiano

Keyword(s):

Food Processing ◽

Protein Modification ◽

Bioinformatics Analysis ◽

Acyl Transfer ◽

Transfer Reactions ◽

Protein Modelling ◽

Sequence Comparisons ◽

Functional Features ◽

Streptomyces Mobaraensis ◽

Acyl Transfer Reactions

Transglutaminases (TGases) are a class of enzyme widely spread in nature, and observed in plants, microorganisms, vertebrates and invertebrates. This enzyme catalyzes post-translational protein modification, by acyl transfer reactions, deamidation and crosslinking (polymerisation). There is a large interest for TGases functions, in particular for human TGases and their involvement in physiopathological processes. In bacteria, TGases appear largely present, although the function of this enzyme is still unknown. Microbial TGases (MTG, or MTGase) are of extreme interest, in particular MTGase from Streptomyces mobaraensis, used in biopolymers industry, in cosmetics production, in wool textiles, and in the food processing. We present the results of bioinformatics analysis on MTGases sequences, based on database searching, sequence comparisons and alignments, phylogenetic tree constructions, with the aim of improving the knowledge of MTGases, in the perspective of investigating by protein modelling and simulations techniques the functional features.

Download Full-text