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Bioactive Peptides (BPs) as Functional Foods: Production Process, Techno-Functional Applications, Health-Promoting Effects, and Safety Issues
Published in Deepak Kumar Verma, Ami R. Patel, Sudhanshu Billoria, Geetanjali Kaushik, Maninder Kaur, Microbial Biotechnology in Food Processing and Health, 2023
Afshin Babazadeh, Majid Nooshkam, Mahnaz Tabibiazar
Endogenous production of oxidative compounds (peroxides and free radicals) during food processing and applying oxidizing agents into the food industry (e.g., aseptic packaging with hydrogen peroxide) might cause oxidation of amino acids. In this case, peroxides can easily oxidize the methionine to methionine sulfoxide, which later can be oxidized to homocysteine acid and methionine sulfone. These two compounds are biologically unavailable. Under acidic conditions such as stomach, methionine can be regenerated from Methionine sulfoxide. Similarly, mono/disulfoxides forms of L-cystine showed bioavailability once they reduced to L-cystine (in the body conditions). Acidic and mild oxidizing environments are able to oxidize Trp. The presence of riboflavin, a photo-sensitizer, in dairy products makes them more susceptible to photo-oxidation. Cys, Trp, His, Met, and Tyr are just some amino acids susceptible to this type of oxidation (Mestdagh et al., 2005). It is enough clear that these types of oxidative changes can cause an increment in the molecular structure changes of antihypertensive and ACE-inhibitory peptides, which consequently may alter the bioactivity of BPs (López-Fandiño et al., 2006).
Biophysical and Biochemical Characterization of Peptide, Protein, and Bioconjugate Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Tapan K. Das, James A. Carroll
Oxidation may commonly occur in proteins at exposed methionine residues to form the methionine sulfoxide product. This is considered a major degradation pathway for many proteins and has the potential to impact their structure and function [11]. In addition, tryptophan and cysteine residues may be oxidized [14,15] and less commonly histidine [17]. Some oxidized products may be separated using chromatography, typically reversed-phase or hydrophobic interaction. Commonly, the oxidized residues may be detected using proteolytic mapping with LC/MS, as described in previous sections.
Product Quality and Process
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
Deamination, or the removal of an amide group, may occur in asparagine to form a succinimide or be further hydrolyzed to aspartate or iso-aspartate (Figure 4.5a). C-terminus glutamine can be cyclized, losing its amide group and forming pyroglutamate (Figure 4.5b). Glycation, the condensation of glucose or other reducing sugars to the ε-amino group of a lysine or the amino group of an N-terminus amino acid, occurs spontaneously in culture fluid (Figure 4.5c). Methionine residue may be oxidized by reacting with reactive oxygen species to form methionine sulfoxide (Figure 4.5d).
Insights into the mechanisms of arsenic-selenium interactions and the associated toxicity in plants, animals, and humans: A critical review
Published in Critical Reviews in Environmental Science and Technology, 2021
Waqar Ali, Hua Zhang, Muhammad Junaid, Kang Mao, Nan Xu, Chuanyu Chang, Atta Rasool, Muhammad Wajahat Aslam, Jamshed Ali, Zhugen Yang
Selenium toxicity or selenosis ensues in plants by two mechanisms: 1) malformed selenoprotein-induced toxicity and 2) oxidative stress-induced Se toxicity. Malformed selenoprotein toxicity in plants occurs in the protein chain by the replacement of SeCys or SeMet with Cys or Met (Gupta & Gupta, 2017). In the plant protein chain, Cys residues play an essential role in the synthesis of protein structure and function, as well as aid in the synthesis of metal-binding sites, metal catalysis, and disulfide linkages. Hence, the replacement of Cys with SeCys causes damage to protein structure and function because SeCys has an exceptional reactivity that can be quickly deprotonated compared with Cys (Gupta & Gupta, 2017; Hondal, Marino, & Gladyshev, 2013). The replacement of Cys with SeCys leads to the dysfunction of methionine sulfoxide reductase because of the considerable diselenide linkage and altered redox potential, which disrupts the enzyme kinetics of the plant (Châtelain et al., 2013; Hondal et al., 2013). Selenium-induced toxicity is caused by disturbance and disparity between the production and scavenging of ROS (Shahid et al., 2018). At elevated doses, Se stress causes a decrease in the level of GSH, and Se behaves as a pro-oxidant and produces ROS, which may cause oxidative stress in plants (Feng, Wei, & Tu, 2013; Hugouvieux et al., 2009).
Mechanistic studies on the reaction between glutathionylcobalamin and selenocysteine
Published in Journal of Coordination Chemistry, 2019
Ilia A. Dereven’kov, Sergei V. Makarov
Selenocysteine (Sec; Figure 1) is a proteinogenic amino acid found in the active site of several enzymes (e.g. glutathione peroxidase, thioredoxin reductase, methionine sulfoxide reductase, iodothyronine deiodinase) [22]. Its structure resembles cysteine, in which sulfur is replaced by selenium. Sec is highly reactive toward reactive oxygen and nitrogen species [23–25], as well as it can be bound by metal ions [26–29]. Sec is capable of reducing Cbls(III) (viz., H2OCbl and cysteinyl-Cbl) to Cbl(II) [30]. The reaction between H2OCbl and Sec proceeds via rate-determining complexation and further rapid decomposition of Sec-Cbl(III) complex to Cbl(II) and selanyl radical [30]. However, the mechanism of the reduction of thiolato-Cbls by Sec remains unclear. This work reports a kinetic and mechanistic study on the interaction between GSCbl and Sec.
Proteomics investigation of molecular mechanisms affected by EnBase culture system in anti-VEGF fab fragment producing E. coli BL21 (DE3)
Published in Preparative Biochemistry and Biotechnology, 2019
Bahareh Azarian, Amin Azimi, Mahboubeh Sepehri, Vahideh Samimi Fam, Faegheh Rezaie, Yeganeh Talebkhan, Vahid Khalaj, Fatemeh Davami
Thioredoxin 1 (Trx) is up-regulated in EnBase cultured cells in the 24 hr phase. Trx, as an electron donor, participates in cell redox homeostasis and activity of various enzymes such as ribonucleotide-diphosphate reductase and methionine sulfoxide reductase.[37] The activity of ribonucleotide-diphosphate reductase is crucial for DNA synthesis during repair and replication of cells, enabling the EnBase cultured cells to achieve higher replication rate and even higher cell density.[38] The role of Trx as a facilitator of protein folding is highly relevant to our experiment. Reducing the environment of cytosol is maintained by Trx through reducing disulfide bonds. Independent of redox activity, Trx facilitates the protein folding through direct interaction or improving the activity of molecular chaperones.[39] This activity of Trx enables the cells to decrease the aggregation rate of recombinant protein, which increases the ratio of soluble protein to insoluble protein. Several studies have indicated the role of Trx and its homologs in refolding denaturated proteins.[40–42]