No abstract

Abiotic stresses induce oxidative stress, which modifies the level of several metabolites including amino acids. The redox control of free amino acid profile was monitored in wild type and ascorbate or glutathione deficient mutant Arabidopsis plants before and after hydroponic treatment with various redox agents. Both mutations and treatments modified the size and redox state of the ascorbate (AsA) and/or glutathione (GSH) pools. The total free amino acid content was increased by AsA, GSH and H 2 O 2 in all 3 genotypes and a very large (3-fold) increase was observed in the GSH-deficient pad2-1 mutant after GSH treatment compared to the untreated wild type plants. Addition of GSH reduced the ratio of amino acids belonging to the glutamate family on a large scale and increased the relative amount of non-proteinogenic amino acids. The latter change was due to the large increase in the content of alpha-aminoadipate, an inhibitor of Glu transport. Most of the treatments increased the Pro content, which effect was due to the activation of genes involved in Pro synthesis. Although all studied redox compounds influenced the amount of free amino acids and a mostly positive, very close (r>0.9) correlation exists between these parameters, a special regulatory role of GSH could be presumed due to its more powerful effect. This may originate from the thiol/disulphide conversion or (de)glutathionylation of enzymes participating in the amino acid metabolism.Abbreviations -Aaa, α-aminoadipic acid; AsA, ascorbic acid; Cysta, cystathione; DHA, dehydroascorbate; DTT, dithiotreitol; GSH, glutathione; GSSG, glutathione disulphide; NPPAs, nonproteogenic amino acids; OAT, ornithine aminotransferase; PDH, proline dehydrogenase; P5CR, pyrroline-5-carboxylate reductase; P5CDH, delta-1-pyrroline-5-carboxylate dehydrogenase; P5CS1, delta This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/ppl.12510 This article is protected by copyright. All rights reserved. Accepted Article1-pyrroline-5-carboxylate synthase 1; P5CS2, delta 1-pyrroline-5-carboxylate synthase 2. IntroductionRedox status has a major role in the regulation of metabolism and is controlled by metabolic processes at the same time (Geigenberger and Fernie 2014). The proper redox status during growth and development under optimal and adverse environmental conditions is maintained by the antioxidant system through the removal of the excess of reactive oxygen species (ROS; Dietz 2008, Suzuki et al. 2012, Kocsy et al. 2013, Considine and Foyer 2014. Accumulation of ROS, such as superoxide radical, hydrogen peroxide, hydroxyl radical and singlet oxygen in high concentration may cause serious injuries or even plant lethality under stress conditions (Bartosz 1997). However, a moderate increase in ROS content may have positive functions as well since, ...

Light-intensity-dependent (low, normal and high) differences in thiol and amino acid metabolism during drought were compared in wheat seedlings. The drought-tolerant genotype (Plainsman) recovered better than the sensitive one (Cappelle Desprez) after the stress as shown by growth and photosynthetic parameters, the levels of which were greater in low and high light, respectively. Glutathione as an antioxidant contributed to this difference, since its level was twofold greater in Plainsman throughout the experiment. In addition, the accumulation of most amino acids even increased in normal light during drought in Plainsman, while such change occurred in Cappelle Desprez only in high light. The higher contents of proline, glutamate and γ-aminobutyrate are especially important because of their involvement in the protection against drought.The transcription of certain genes related to amino acid and glutathione metabolism and various antioxidants was even induced by higher light intensities before drought, which can contribute to the subsequent increase in the amount of the corresponding metabolites during stress. Increase in light intensity activated various protective mechanisms including greater accumulation of glutathione, proline and other amino acids during drought, which contributed to the efficient recovery of wheat after stress. K E Y W O R D S drought, free amino acids, glutathione, light intensity, photosynthesis, wheatThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Enzymatic hydrolysis of soybean milk proteins with cysteine protease papain was performed in an advanced bioreactor, operated with batch mode. In soybean milk protein hydrolysis reaction, enzyme and substrate ratio and reaction temperature were varied, ranging from 0.029:100-0.457:100 and 30-60 • C, respectively. The degree of hydrolysis of soybean milk proteins was increased with increase of enzyme and substrate (soybean milk protein) ratio. However, the degree of hydrolysis was increased due to change of reaction temperature from 30 • C to 60 • C with enzyme and substrate ratio 0.229:100 and was reduced when hydrolysis reaction was performed with enzyme and substrate ratio 0.11:100 at hydrolysis temperature 60 • C. Antioxidant capacity of enzyme-treated milk had a similar trend with degree of hydrolysis. In a later exercise, a membrane bioreactor was adopted for continuous production of antioxidant and antibacterial peptides from soybean milk. The membrane bioreactor was operated for 12 h with constant feeding. Ceramic-made tubular membrane with a pore size 20 nm was used. Application of static turbulence promoter in a membrane separation process was investigated and its positive effects, with respect to higher permeate flux and lower energy consumption in filtration process, were proven. Antioxidant capacity and antibacterial activity against Bacillus cereus of enzyme-hydrolyzed milk and permeate from membrane were confirmed.

SummaryHypoallergenic antibacterial low-molecular-mass peptides were produced from defatted soybean meal in a membrane bioreactor. In the fi rst step, soybean meal proteins were digested with trypsin in the bioreactor, operated in batch mode. For the tryptic digestion of soybean meal protein, optimum initial soybean meal concentration of 75 g/L, temperature of 40 °C and pH=9.0 were determined. Aft er enzymatic digestion, low-molecular-mass peptides were purifi ed with cross-fl ow fl at sheet membrane (pore size 100 μm) and then with tubular ceramic ultrafi ltration membrane (molecular mass cut-off 5 kDa). Eff ects of transmembrane pressure and the use of a static turbulence promoter to reduce the concentration polarization near the ultrafi ltration membrane surface were examined and their positive eff ects were proven. For the fi ltration with ultrafi ltration membrane, transmembrane pressure of 3·10 5 Pa with 3-stage discontinuous diafi ltration was found optimal. The molecular mass distribution of purifi ed peptides using ultrafi ltration membrane was determined by a liquid chromatography-electrospray ionization quadrupole time-of-fl ight mass spectrometry setup. More than 96 % of the peptides (calculated as relative frequency) from the ultrafi ltration membrane permeate had the molecular mass M≤1.7 kDa and the highest molecular mass was found to be 3.1 kDa. The decrease of allergenic property due to the tryptic digestion and membrane fi ltration was determined by an enzyme-linked immunosorbent assay and it was found to exceed 99.9 %. It was also found that the peptides purifi ed in the ultrafi ltration membrane promoted the growth of Pediococcus acidilactici HA6111-2 and they possessed antibacterial activity against Bacillus cereus.