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Recent Advances in Artificial Cells With Emphasis on Biotechnological and Medical Approaches Based on Microencapsulation
Published in Max Donbrow, Microcapsules and Nanoparticles in Medicine and Pharmacy, 2020
This began as the preparation of smaller artificial cells by direct cross-linking of hemoglobin molecules to form a polyhemoglobin membrane2-5 (Table 2). Decrease in the diameter gave rise to very small polyhemoglobin microspheres.2-5 Further development along this line is shown in Table 2. Smaller polyhemoglobin units consisting of four to five hemoglobin molecules are soluble. In this form the cross-linkage prevents the hemoglobin from breaking down into dimers. Binding a cofactor, pyridoxal phosphate, to hemoglobin improves the release of oxygen. This results in the formation of pyridoxalated polyhemoglobin. Animals do not survive rapid removal of 2/3 of their blood volume even with adequate fluid replacement. When pyridoxalated polyhemoglobin was given to replace the lost blood volume, the animals recovered. Several centers (Table 2) have developed this approach, one having already reached the stage of clinical testing in patients.
Organic and Inorganic Supramolecular Catalysts
Published in Jubaraj Bikash Baruah, Principles and Advances in Supramolecular Catalysis, 2019
Certain enzymes have pyridoxamine or pyridoxal phosphate as a cofactor to catalyse proton transfer reactions. In certain biological reactions, base groups bind to metal ions, where the metal ion acts as a Lewis acid. One such mimicking reaction is the transamination reaction performed by pyridoxamine containing zinc complex (2.73c), which has an internally linked base group. Upon reaction of the complex with keto-carboxylic acid, a transamination reaction occurs. The complex is chiral; hence, a stereoselective amino acid is formed (Figure 2.73). A proton from the CH2 group is extracted by the dimethylamino group and the proton is transferred stereo-specifically to form an intermediate (2.73d). The intermediate hydrolyses to form chiral amino acid (2.73f). The reaction is catalytic, as further reaction of amino acid with the 2.73e initial complex is regained and a catalytic cycle is maintained.
Triticum Aestivum L.): Effects on the Distribution of Protein Sub-Fractions, Amino Acids, and Starch Characteristics
Published in Megh R. Goyal, Susmitha S. Nambuthiri, Richard Koech, Technological Interventions in Management of Irrigated Agriculture, 2018
Divya Jain, Bavita Asthir, Deepak Kumar Verma
GOT is a pyridoxal phosphate-dependent enzyme present in cytoplasmic and mitochondrial forms. GOT is the main enzyme involved in NH4+ assimilation.104 This enzyme is also known as aspartate aminotransferase and is one of the most active enzymes in the cell. It exists in mitochondrial and cytosolic variants. The metabolic importance of this enzyme is that it brings about a free exchange of amino groups between glutamate (which is the most common amino acid) and aspartate which is a second major amino acid pool. Glutamate and aspartate are each required for separate but essential steps in the urea cycle. The free movement of nitrogen between the glutamate and aspartate pools is an important balancing process that is vital for normal cellular metabolism. The urea cycle consists of five reactions: two mitochondrial and three cytosolic (Table 10.1). The cycle converts two amino groups, one from NH4+ and one from ASP, and a carbon atom from HCO3−, into the relatively non-toxic excretion product urea at the cost of four “highenergy” phosphate bonds (three ATP hydrolyzed to two ADP and one AMP). Ornithine is the carrier of these carbon and nitrogen atoms.
The purification and functional study of new compounds produced by Escherichia coli that influence the growth of sulfate reducing bacteria
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Oluwafemi Adebayo Oyewole, Julian Mitchell, Sarah Thresh, Vitaly Zinkevich
The vitamin stock solution contains 0.6 mg vitamin B1 (thiamine), 0.2 mg vitamin B2 (riboflavin), 0.5 mg vitamin B3 (nicotinic acid), 0.6 mg vitamin B5 (pantothenic acid), 0.6 mg vitamin B6 (pyridoxal phosphate), 0.05 mg vitamin B12 (cobalamin), 100 mg vitamin C (L-ascorbic acid), 0.01 mg vitamin H (biotin),1 L dH2O and the trace elements consist of 1.5 g C6H9NO6, 3.0 g MgSO4 · 7H2O, 0.5 g MnSO4·H2O, 1.0 g NaCl, 0.1 g FeSO4 · 7H2O, 0.1 g CoSO4 · 7 H2O, 0.1 g NiCl2 · 6H2O, 0.1 g CuCl2 · 2H2O, 0.1 g ZnSO4 · 7H2O, 0.01 g CuSO4 · 5H2O, 0.01 g KAl(SO4)2 · 12H2O, 0.01 g H3BO3, 0.01 g Na2MoO4 · 2H2O, 0.001 g Na2SeO3 and 1 L dH2O.
Production of γ-aminobutyric acid in Escherichia coli by engineering MSG pathway
Published in Preparative Biochemistry and Biotechnology, 2018
Ping Yu, Kaifei Chen, Xingxing Huang, Xinxin Wang, Qian Ren
E. coli GAD has six subunits and the molecular weight of each subunit, which is pyridoxal phosphate (PLP)-dependent, is 52.6 kDa. The enzyme has a strong substrate specificity for l-glutamate and its optimal pH is about 3.8.[42–44]E. coli can survive in an extremely acidic environment mainly because of an intracellular glutamate-dependent acid resistance system.[45–47] This acid resistance system consists of three key proteins, including two glutamate decarboxylase isozymes (GadA and GadB) and the glutamate/GABA antiporter (GadC). When E. coli is under acidic conditions, GadC can ship extracellular glutamate into cytoplasm, where GadA and GadB catalyze the decarboxylation reaction, which consumes a hydrogen ion to produce GABA. GadC ships the produced GABA out of the cell (Figure 1a). Thus, it is interesting to investigate if the coexpression of glutamate decarboxylases (GadA and GadB) and glutamate/GABA antiporter (GadC) can improve the GABA production in engineered E. coli cells.
Key Microbes and Metabolic Potentials Contributing to Cyanide Biodegradation in Stirred-Tank Bioreactors Treating Gold Mining Effluent
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Doyun Shin, Jeonghyun Park, Hyunsik Park, Jae-Chun Lee, Min-Seuk Kim, Jaeheon Lee
Using PiCRUSt, the relative abundances of cyanide- and alkaline-shock-related genes in the reactors was identified as shown in Figure 5. There are three categories of cyanide-related genes, involved in either cyanide degradation, resistance, or production. Cyanide biodegradation involves hydrolytic, oxidative, reductive, and substitution/transfer pathways (Ebbs, 2004; Raybuck 1992). Each pathway has its own enzymes: cyanide hydratase (formamide hydrolyase, EC 4.2.1.66) and cyanidase (cyanate amidohydrolyase, EC 3.5.5.3) (hydrolytic); cyanide monooxygenase and dioxygenase (oxidative); nitrogenase (reductive); and rhodanese (thiosulfate: cyanide sulfur transferase, EC 2.8.1.1), mercaptopyruvate sulfurtransferase (EC 2.8.1.2), and pyridoxal phosphate enzymes (substitution/transfer). The cyanide resistance-related gene is cyanide-insensitive cytochrome bd quinol oxidase, because some facultative Proteobacteria (Comolli and Donohue 2002; McDonald 2008) use cyanide-insensitive alternative oxidase as an alternative respiratory route (Voggu et al. 2006). A cyanide-producing enzyme, hydrogen cyanide synthase (hcnABC), is also found in Proteobacteria, including C. violaceum, fluorescent pseudomonads, and the genus Rhizobium (Blumer and Haas 2000). Other cyanide-related genes have been reported, but they are not included in the Greengenes database. Due to the limited database availability, PiCRUSt cannot replace whole metagenome profiling. However, it is still useful to provide supplemental data on the functional potential of genes based on 16S rRNA analyses. As shown in Figure 5a, on day 0, all the reactors inoculated only with sludge or with C. violaceum and activated sludge had some level of cyanide-degrading and cyanide-resistance potential. With cyanide addition and time, the cyanide-degradation potential decreased, except in the S-50 reactor, in which a small portion of hydrolytic cyanide degradation activity was observed. In the CS-200 and S-200 reactors, almost all the cyanide degradation potential disappeared but the cyanide-resistance potential was maintained with cyanide addition and time. In the reactors inoculated only with the cyanide-degrading bacterial mixture or the bacterial mixture and sludge (Figure 5b), cyanide production potential was observed at an early stage, but disappeared after 7 days. Thus, the first possibility which the cyanide production may contribute the low decrease of cyanide concentration in the effluent was refuted.