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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
Urease is an enzyme that converts urea into ammonia and carbon dioxide. Artificial cells containing urease, when injected into animals, effectively convert urea to ammonia.2-5 Urease artificial cells in a hemoperfusion device can also convert urea in blood to ammonia.13 Incorporation of an ammonia adsorbent in the microcapsules can then remove the ammonia formed. A more convenient approach is to give urease artificial cells and ammonia adsorbent by mouth5,27,28 as urea can diffuse readily from the blood into the intestine. Research in animals shows that oral ingestion of these artificial cells removes urea and lowers body urea level.5,27,28 Clinical tests in patients also show similar results.29 However, the ammonia adsorbent needs improvement to raise its adsorption capacity and lower the amount required. Other ammonia adsorbents like zeolites are being investigated.30
Plant Nutrition and Turf Fertilizers
Published in L.B. (Bert) McCarty, Golf Turf Management, 2018
A means of delaying the conversion of ammonium to nitrate is N stabilizers. Two types are nitrification inhibitors and urease inhibitors. Nitrapyrin (N-Serve), encapsulated nitrapyrin (Instinct), and dicyandiamide (DCD or Didin) are nitrification inhibitors that delay the conversion of ammonium to nitrite during nitrification. Urease inhibitors such as NBPT [N-(n-butyl) thiophosphoric triamide] and PPD [phenyl-phosphoro-diamidate] slow the activity of urease. UMAXX (47-0-0) and UFLEXX (46-0-0) are commercial stabilized urea products that inhibit or delay nitrification utilizing DCD and urease (NBPT) activity. UFLEXX delays nitrification for six to eight weeks, while UMAXX delays this for 12 to 16 weeks. Agrotain (NBPT), Stay-N, and NZone are commercial urease inhibitors. SuperN is a liquid mixture of DCD and NBPT, while HYDREXX is a granular mixture of them.
Magnetic Particle Transport in Complex Media
Published in Nguyễn T. K. Thanh, Clinical Applications of Magnetic Nanoparticles, 2018
Lamar O. Mair, Aleksandar N. Nacev, Sagar Chowdhury, Pavel Stepanov, Ryan Hilaman, Sahar Jafari, Benjamin Shapiro, Irving N. Weinberg
Walker et al. used porcine gastric mucins (PGMs) as a model system for studying the transport of magnetically rotated microhelices.81 As discussed previously, the mucin network creates a dense and sticky network, which significantly hinders both diffusive and driven particle motion. While unmodified synthetic particles experience significant motion suppression, some microorganisms have developed tools for efficiently moving through mucus. The microorganism Helicobacter pylori secretes large local quantities of urease. Urease catalyzes the hydrolysis of urea, releasing ammonia. This chemical cascade serves to increase the pH of the surrounding mucus, thereby inducing a sol-gel transition capable of liquefying the mucus in the vicinity of the H. pylori cell. Taking a cue from nature, Walker et al. modified the surfaces of nanohelices with urease and demonstrated that, by doing so, nanohelices could be efficiently moved through porcine gastric mucin solutions.
Enzyme activities and heavy metal interactions in calcareous soils under different land uses
Published in International Journal of Phytoremediation, 2023
Erdal Sakin, İbrahim Halil Yanardağ, Emrah Ramazanoğlu, Hamza Yalçın
Urease is one of the important extracellular enzymes and is involved in mineralization processes in agricultural soils. Therefore, this enzyme has an important place in the soil. The urease enzyme is an important enzyme that catalyzes the hydrolysis of urea to ammonia (NH2CONH2 + H2O → 2NH3 + CO2). The oxidation of ammonia at the end of this catalysis event is very important in agricultural and environmental care (Hutchinson and Viets, 1969). Although there are many studies on the distribution of urease enzyme activity in the soil profile, the relative factors affecting this enzyme throughout the profile have not been determined. Dehydrogenase, which is one of the important intracellular enzymes, is the enzyme used in the determination of biological activity and biomass (XH2 + A → X + AH2) in soil. They are the main representatives of the oxidoreductase enzyme class. Dehydrogenases are one of the most important of all enzymes in the soil environment and are used as an indicator of general soil microbial activity (Yang et al.2016).
A novel and sustainable approach for biotransformation of phosphogypsum to calcium carbonate using urease producing Lysinibacillus sphaericus strain GUMP2
Published in Environmental Technology, 2023
Prajakta Pratap Patil, Meghanath Prabhu, Srikanth Mutnuri
Research has been carried out to demonstrate the bioremediation potential of L. sphaericus strains with chromate reduction capacity isolated from different contaminated environments and naturally metal-rich soils [27–29]. The strain JG-A12 isolated from uranium-mining waste piles in Germany could reversibly bind Al, Cd, Cu, Pb, and Ur [30]. In another study, L. sphaericus strain CBAM5 with an arsenate reductase gene showed resistance to 200 mM arsenic [31]. Biomineralization of calcium carbonate by urease-producing L. sphaericus was reported recently [32]. However, to the best of our knowledge, the role of L. sphaericus in the biotransformation of PG to calcite and ammonium sulfate was never studied before. We also elucidate the probable mechanism behind the biomineralization of calcium carbonate by urease-producing bacteria. Urease-producing microbes hydrolyze urea in the presence of urease into ammonia and carbon dioxide (Equation 1).
A centipede like thiocyanate-bridged muti-nuclear copper(I/II) complex derived from 2-(((2-(dimethylamino)ethyl)imino)methyl)-5-fluorophenol with urease inhibitory activity
Published in Journal of Coordination Chemistry, 2022
Xinhui Feng, Wenlong Wu, Yuqing Gu, Li Zhang, Shiyi Wang, Jie Zhao, Jing Ji, Dahua Shi, Zhonglu You
Urease (amidohydrolase; EC 3.5.1.5) is widely found in most organisms such as bacteria, fungi, algae, plants, as well as in soil. Urease enzyme of Jack bean is a nickel-containing enzyme, which was first crystallized in 1926. The hydrolysis of urea to ammonia by the catalytic reaction of urease has a rate 1014 times faster than that without urease. High concentration of NH3 released during the decomposition of urea causes a significant increase in pH, thus increasing the alkalinity of soil, which leads to damage of the plants by depriving them from their essential nutrients [25, 26]. Moreover, urease plays a vital role in many pathogenic processes in humans and animals. It showed a major role in urinary catheter incrustation, peptic ulceration, pyelonephritis, kidney stone, hepatic encephalopathy, urolithiasis, and arthritis [27, 28]. A good way to control the activity of urease with inhibitors [29, 30]. Although many urease inhibitors have been described over the past decades, a large number of them were prevented from being used because of their low inhibition efficiency [31, 32]. We have reported a number of Schiff base complexes as urease inhibitors. Among them, copper complexes show prominent activities [33–36]. To construct interesting thiocyanate-bridged Schiff base complexes, and to explore new urease inhibitors, in the present work, a new thiocyanate-bridged multi-nuclear copper(I/II) complex, [Cu2L(CH3OH)(NCS)3]n, derived from 2-(((2-(dimethylamino)ethyl)imino)methyl)-5-fluorophenol (HL), is presented.