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Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
ASN is an abbreviation for asparagine (C4H8N2O3); and is also known as asparamide. Asparagine is an a-amino acid that is found in many proteins, particularly in plant proteins, such as in asparagus. Asparagine is closely related to the amino acid aspartic acid, into which it is easily hydrolized.
Toxicity, metabolism, and mitigation strategies of acrylamide: a comprehensive review
Published in International Journal of Environmental Health Research, 2022
Leila Peivasteh-Roudsari, Marziyeh Karami, Raziyeh Barzegar-Bafrouei, Samane Samiee, Hadis Karami, Behrouz Tajdar-Oranj, Vahideh Mahdavi, Adel Mirza Alizadeh, Parisa Sadighara, Gea Oliveri Conti, Amin Mousavi Khaneghah
Potato products are considered the most popular daily snacks in the world, and therefore high consumption of such products, especially French fries and potato chips, can result in excessive intake of AA levels for children and teenagers, nearly three times more AA than adults on a per kg body weight basis (Tran et al. 2017). Having nearly one‐third of the total free amino acids, asparagine has been found as the leading free amino acid in potatoes, increasing the potential for AA formation (Matthäus and Haase 2014). In 2015, the European Food Safety Authority (EFSA) revealed that French fries and potato chips consumed in the European Union contain about 308 μg kg−1 and 389 μg kg−1, respectively (EFSA 2015; Başaran and Aydın 2022). In the US, 38% of dietary AA came from processed potato products, 16% from fries prepared in restaurants, 12% from oven-baked French fries, and 10% from potato chips (Bethke 2018). Regulation (EU) 2017/2158 set a Benchmark Level for AA in French fries (500 µg kg−1) and potato crisps (750 µg kg−1) (EC 2017).
Computational analysis of nonenzymatic deamidation of asparagine residues catalysed by acetic acid
Published in Molecular Physics, 2021
Tomoki Nakayoshi, Kota Wanita, Koichi Kato, Eiji Kurimoto, Akifumi Oda
Post-translational deamidation of asparagine (Asn, l-Asn) residues occurs in peptides and proteins, and proceeds nonenzymatically. Asn-residue deamidation in peptides and proteins converts Asn into aspartic acid (Asp) and/or isoaspartic acid (isoAsp) residues via succinimide (Suc) intermediates [1–3]. Scheme 1 shows the Suc-intermediate-mediated pathway for deamidation of Asn residues. First, the side-chain carbonyl carbon of the Asn residue is nucleophilically attacked by the main-chain amide nitrogen of the C-terminal side adjacent residue, i.e. (n + 1) residue in order to form a five-membered ring l-Suc intermediate. l-Suc intermediates are easily hydrolysed to form l-Asp and l-isoAsp residues. The formation of l-Asp and l-isoAsp residues occurs heterogeneously, and l-Asp and l-isoAsp residues typically form in a ratio of 1:3 [1–3]. Some l-Suc intermediates formed in peptides and proteins undergo stereoinversion to form d-Suc intermediates, and d-Asp and d-isoAsp residues are formed by the hydrolysis of d-Suc intermediates [1–3]. The Suc intermediate is relatively stable, and the accumulation of Suc in some peptides and proteins has been experimentally confirmed [4–7]. The formation rate of Suc intermediates by Asn-residue deamidation is strongly affected by the size of the (n + 1) residue [8–11]. Specifically, when the (n + 1) residue is small, as in the case of glycine, alanine, and serine, Asn-residue deamidation proceeds rapidly. Conversely, when the (n + 1) residue is bulky, as with valine, leucine, and isoleucine, Asn-residue deamidation is extremely limited.
Optimization of culture conditions and bench-scale production of anticancer enzyme L-asparaginase by submerged fermentation from Aspergillus terreus CCT 7693
Published in Preparative Biochemistry and Biotechnology, 2019
T. A. Costa-Silva, D. I. Camacho-Córdova, G. S. Agamez-Montalvo, L. A. Parizotto, I. Sánchez-Moguel, A. Pessoa-Jr
L-Asparagine is the main substrate of L-asparaginase and this amino acid is an essential constituent in various metabolic routes. It seems unlikely that the elevated concentration of this enzyme would be easily available within the microbial cell. Therefore, the hydrolytic activity must be regulated through either cell isolation (compartmentalization in the cytoplasm, periplasmic space, or organelles) or metabolic regulation.[24] Nitrogen repression is an example of a metabolic alteration in fungi, and several studies have proven that nitrogen deprivation also controls L-asparaginase production.[13,25] Nitrogen starvation results in ammonium derepression and consequent high enzyme activity.[13] Herein, we observed that removing the inorganic source of nitrogen was required for stimulating L-asparaginase biosynthesis by Aspergillus terreus CCT 7693. This filamentous fungus cells grown on easily assimilated nitrogen source was transferred into nitrogen-free conditions to ensure the activation of secondary nitrogen source degrading pathways (proline assimilation), thereby stimulating L-asparaginase production. The presence of ammonium in the media had the same regulatory mechanism as nitrate and both components did not inhibit asparaginase activity in vitro (unpublished results). These findings agree with the results found by Drainas et al.[13] who postulated that protein synthesis is necessary for ammonium repression to take place: L-asparaginase is inactivated by protease activity or L-asparaginase biosynthesis is blocked by control proteins mediated by ammonium. The presence of glucose also showed an inhibition of L-asparaginase biosynthesis; therefore, its concentration was adjusted in the production phase: 14–2 g·L−1. The possible explanation for the role of glucose in the control of L-asparaginase biosynthesis is the acid production or catabolite repression by decreasing cAMP level in the microbial cell.[26–28]