Consideration of Glutamine Synthetase as a Multifunctional Protein
James F. Kane in Multifunctional Proteins: Catalytic/Structural and Regulatory, 2019
The amino acid glutamine is not only essential for protein synthesis but also as a precursor for other nitrogen-containing compounds in cells. The enzyme responsible for glutamine production, glutamine synthetase, is widely distributed in microorganisms, plants, and animals and catalyzes the conversion of glutamate and ammonia to glutamine with the cleavage of ATP to ADP and Pi Glutamine synthetase occupies a central position in cell physiology, because it forms an intersection of pathways for carbon metabolism, ammonia assimilation, amino acid synthesis, and the availability of glutamate and glutamine as precursors for other cell constituents. Many microorganisms use glutamate synthase, which converts glutamine and α-ketoglutarate to two glutamates, as the primary route for glutamate production. For these organisms, glutamine synthetase has the interesting physiological role of using glutamate as a substrate to make glutamine, which serves as a product for other cell metabolism and as a precursor for producing more glutamate. In this role, glutamine synthetase is in a cyclic reaction necessary for making one of its substrates.
Micronutrients
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Vitamin B2 or riboflavin is an essential vitamin of group B. It is a water-soluble, yellow-orange organic compound and is heat stable. Riboflavin is the central component of the coenzymes: flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), and acts as a co-factor in numerous enzymatic reactions. It is therefore important for energy production, enzyme function, and normal protein, fatty acid and amino acid synthesis (3, 9, 33, 37–38). It mediates the transfer of electrons in biological oxidation-reduction reactions. It is also involved in the metabolism of folate, vitamin B12, vitamin B6, and other vitamins. It also helps to maintain the integrity of mucous membranes, skin, the eyes and nervous system (38). The role of riboflavin has also been credited in the prevention of a wide array of health diseases like migraine, anemia, cancer, hyperglycemia, hypertension, diabetes mellitus, and oxidative stress, directly or indirectly (38). A deficiency of riboflavin named ariboflavinosis is manifested in swollen tongue, skin eruption, and eye irritation (3, 33, 37–38). Riboflavin deficiency has profound effects on iron absorption, metabolism of tryptophan, mitochondrial dysfunction, the gastrointestinal tract, brain dysfunction, and metabolism of other vitamins (38). Although riboflavin is involved in all areas of metabolism, and deficiency is widespread on a global scale, deficiency is not fatal (33). Riboflavin deficiency is usually associated with other vitamin B complex deficiencies; isolated riboflavin deficiency is rare (3, 33).
Nutritional Ergogenic Aids: Introduction, Definitions and Regulatory Issues
Ira Wolinsky, Judy A. Driskell in Nutritional Ergogenic Aids, 2004
Glutamine in the liver and kidney is catabolized to glutamate and ammonia with the help of the enzyme glutaminase.1,2 In the absorptive state or during periods of alkalosis, liver glutaminase activity increases, producing ammonia for the urea cycle.1,2 Under acidotic state, the use of glutamine in the urea cycle decreases, and instead, glutamine is released from the liver and transported to the kidneys, where it is catabolized by the renal tubular enzyme glutaminase to produce ammonium and glutamate.1,2 This glutamate may be catabolized by the enzyme glutamate dehydrogenase to produce a-keto-glutarate, which can be used for energy production via the citric acid cycle or nonessential amino acid synthesis via the transamination process and
Upregulation of peroxide scavenging enzymes and multidrug efflux proteins highlight an active sodium hypochlorite response in Pseudomonas fluorescens biofilms
Published in Biofouling, 2019
Daniel Lipus, Amit Vikram, Djuna Gulliver, Kyle Bibby
A previous study has made similar observations in gene expression with exposure to hydrogen peroxide in planktonic Pseudomonas populations, suggesting that oxidative stress changes the regulation of LysM and related genes (Chang, et al. 2005). One possible explanation is that sodium hypochlorite interferes with transport proteins at the membrane surface. Stressed cells might also neglect non-essential active and facilitated transport through the cell membrane, resulting in decreased transcription levels. This explanation also applies to the observed downregulation of genes encoding proteins involved in amino acid synthesis and metabolism and energy metabolism related processes, which were also down-regulated. Examples were genes encoding an acetylornithine deacetylase (PFLU_RS10165), an NAD(P)-dependent oxidoreductase (PFLU_RS07415), and a gene sharing similarity to a NADP-dependent 3-hydroxy acid dehydrogenase-like gene ydfG (PFLU_RS21225) (Table 2). Similarly, repression of these genes has been previously observed in planktonic Pseudomonas cultures in response to hydrogen peroxide, sodium hypochlorite, and peracetic acid (Chang, et al. 2005, Small, et al. 2007a).
Toxicity of the herbicides used on herbicide-tolerant crops, and societal consequences of their use in France
Published in Drug and Chemical Toxicology, 2022
Jean-Paul Bourdineaud
In Arabidopsis thaliana, up-regulated genes are those encoding enzymes involved in the metabolization of herbicides such as cytochrome P450 (CYP), GST and UDP glycosyl transferases (UGT), and allowing detoxification such as ATP-binding cassette (ABC) transporters and multidrug resistance (MRP) and toxin extrusion (MATE) protein families, and the iron superoxide dismutase Fe-SOD genes (FSD). Also up-regulated genes comprise those encoding ribosome associated proteins or protein synthesis initiation factors (eIF4A, eIF4E and eIF5), and some involved in amino acid synthesis. The mitochondrial function is also impacted since the genes encoding mitochondrial genes alternative oxidases ATAOX1a and ATAOX1b, along with two mitochondrial NADH dehydrogenases, NDB2 and NDB4 are up-regulated. Down-regulated genes are those involved in cell wall biosynthesis, along with genes involved in the neutralization of the oxidative stress such as those encoding copper-zinc superoxide dismutases Cu/ZnSOD (CSD), ascorbate peroxidases (APX), and glutathione peroxidases (GPX).
Probiotic-directed modulation of gut microbiota is basal microbiome dependent
Published in Gut Microbes, 2020
Qiangchuan Hou, Feiyan Zhao, Wenjun Liu, Ruirui Lv, Wei Wei Thwe Khine, Jia Han, Zhihong Sun, Yuan-Kun Lee, Heping Zhang
Functional analysis showed that there were significant differences between the two enterotypes in many metabolic modules. For example, three modules related to lipopolysaccharide metabolism were significantly more abundant in PF enterotypes than FB enterotypes, while many pathways related to human essential amino acid synthesis were significantly higher in FB enterotypes than PF enterotypes. Lipopolysaccharides are components of the cell membranes of gram-negative bacteria, and gut microbiota-derived lipopolysaccharides and systemic endotoxemia are involved in the onset and progression of atherosclerosis, inflammatory bowel disease, obesity and related metabolic diseases, and nonalcoholic steatohepatitis.52–54 Essential amino acids are those amino acids that cannot be synthesized by the human body, or cannot be synthesized at a speed that meets requirements and must be provided from external sources. A lack of essential amino acids leads to a series of problems including metabolic disorders and a decline in immune resistance.55 Considering that the biosynthesis pathway for lipopolysaccharide was enriched in PF enterotypes and various modules related to the synthesis of essential amino acids were enriched in FB enterotypes, we speculate that the composition of gut microbiota of FB enterotypes may be more beneficial to the health of adults. After LCZ consumption, the enterotype of many adults changed from PF to FB with a significant decrease in abundance of the lipopolysaccharide biosynthesis module in both enterotypes confirms the probiotic effect of LCZ.
Related Knowledge Centers
- Amination
- Biochemistry
- Enzyme
- Essential Amino Acid
- Glutamic Acid
- Metabolic Pathway
- Transaminase
- Transamination
- Amino Acid
- Α-Ketoglutaric Acid