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Quantitative Proteomics Analysis of Barley-Based Liquid Feed and the Effect of Protease Inhibitors and NADPH-Dependent Thioredoxin Reductase/Thioredoxin (NTR/Trx) System

Sultan, Abida, Andersen, Birgit, Christensen, Jesper Bjerg, Poulsen, Hanne Damgaard, Svensson, Birte, Finnie, Christine
Journal of agricultural and food chemistry 2019 v.67 no.22 pp. 6432-6444
digestibility, feed additives, feeding methods, grains, liquids, livestock, monitoring, nutrient availability, outer membrane proteins, oxidoreductases, proteinase inhibitors, proteolysis, proteomics, seed storage, soaking, solubility, storage proteins, thioredoxins
Liquid feeding strategies have been devised with the aim of enhancing grain nutrient availability for livestock. It is characterized by a steeping/soaking period that softens the grains and initiates mobilization of seed storage reserves. The present study uses 2D gel-based proteomics to investigate the role of proteolysis and reduction by thioredoxins over a 48 h steeping period by monitoring protein abundance dynamics in barley-based liquid feed samples supplemented with either protease inhibitors or NADPH-dependent thioredoxin reductase/thioredoxin (NTR/Trx). Several full-length storage proteins were only identified in the water-extractable fraction of feed containing protease inhibitors, illustrating significant inhibition of proteolytic activities arising during the steeping period. Application of functional NTR/Trx to liquid feed reductively increased the solubility of known and potentially new Trx-target proteins, e.g., outer membrane protein X, and their susceptibility to proteolysis. Thus, the NTR/Trx system exhibits important potential as a feed additive to enhance nutrient digestibility in monogastric animals.