Effects of Food Processing, Storage, and Cooking on Nutrients in Plant-Based Foods
Nicole M. Farmer, Andres Victor Ardisson Korat in Cooking for Health and Disease Prevention, 2022
Blanching is mild heat treatment used in most vegetables and cut fruits prior to freezing. Its main purpose is the inactivation of enzymes that cause flavor or texture degradation during frozen storage. Examples of these enzymes include polyphenol oxidase, responsible for the development of undesirable colors through enzymatic browning (text box 1), and lipoxygenase that promotes the production of peroxides, which are responsible for undesirable flavors and odors. Of note, peroxidase activity is used as a proxy for lipoxygenase activity as a maker of the effectiveness of blanching because the activity of the latter is difficult to assess.
Introduction to Vaccination
Mesut Karahan in Synthetic Peptide Vaccine Models, 2021
Inactivated vaccines are produced by killing the disease-causing microbe with chemicals, heat, or radiation. The main reason for inactivation is the inability to attenuate the microorganism (attenuation) and the risk of returning to the mutant form. Most of the vaccines licensed to date have been developed based on “isolate, inactivate, and inject” the causative agent of disease (Pasteur’s principles) (Plotkin 2009). Inactivated vaccines are usually used with combinations or used as adjuvants. The adjuvant is used to increase the effect of the drug or the active substance of the vaccine (Altınsoy 2007). There are considerable differences at titer when the adjuvant is added and when the adjuvant is not added. Bacterial cell wall components, liposomes, and synthetic polymers often show an adjuvant effect. Inactive vaccines generally do not tend to cause infection; active vaccines can rarely cause local, specific, and risk-free infections in small areas (Pelit Arayıcı 2015).
Site-Specific Chemical Modification of Proteins
Roger L. Lundblad in Chemical Reagents for Protein Modification, 2020
In some of these situations it is possible to fractionate the protein into uniquely modified species. The separation of carboxymethyl-HIS12-pancreatic ribonuclease from carboxymethyl-HIS119-pancreatic ribonuclease is a classic example of this type of a situation.11 More recently, it has been possible to separate various derivatives of lysozyme obtained from the modification of carboxyl groups.12 Frequently, however, while there is good evidence that multiple modified species are obtained as a result of the reaction, it is not possible to separate uniquely modified species. As an example, consider recent studies on the modification of thrombin by tetranitromethane.13 In these studies, apparent stoichiometry of inactivation was obtained with equivalent modification of two separate tyrosine residues (Tyr 71 and Tyr 85 in the B chain) and it was not possible to separate these derivatives. As a result it was necessary to use techniques such as those described below to obtain an understanding of the inactivation reaction.
Enhancing the antibacterial effect of iron oxide and silver nanoparticles by extremely low frequency electric fields (ELF-EF) against S. aureus
Published in Electromagnetic Biology and Medicine, 2023
Ebtesam A. Mohamad, Marwa A Ramadan, Marwa M. Mostafa, Mona S. Elneklawi
Inactivation of bacteria is an essential step in food safety. To prevent bacterial contamination of food, synthetic preservatives, as sorbates, nitrates and nitrites are widely used in the food industry due to their antibacterial activity low cost. Customers are recently considering the use of synthetic chemical preservatives due to the negative health effects (Yu et al. 2021). The process of pasteurization is used to preserve liquids or fruit juices to inactivate bacteria and extend the shelf life. But the disadvantage of using heat to inactivate microorganisms is the loss of vitamins or heat-sensitive materials (Kantala et al. 2022). The development of multidrug-resistant (MDR) strains is due to the frequent improper use of antibiotics that leads to the spread of bacterial development in humans (da Silva et al. 2019; Wang et al. 2021). It should be noted that the outbreak of the Corona-virus 2019 pandemic may increase antimicrobial resistance as a result of the extensive use of antibiotics to treat patients (Editorial 2020; Rawson et al. 2020). Therefore, alternative strategies to combat antibiotic-resistant bacteria are urgently needed.
Mechanism-based inactivation of cytochrome P450 3A by evodol
Published in Xenobiotica, 2023
Enzyme inactivation kinetic assays were conducted as described below. Briefly, the primary incubation mixtures contained HLM (0.1 mg protein/mL), evodol (0, 0.1, 0.5, 1, 5, 10, 50, and 100 μM), NADPH (1 mM), MgCl2 (3 mM) in 0.1 M phosphate buffer (pH 7.4) with a total incubation volume of 100 μL. Each incubation was prepared in triplicates. After pre-incubation at 37 °C for 5 min, the reaction was started via the addition of NADPH. Afterwards, at predefined time points (0, 15, 30, and 60 min), a 20 μL aliquot of each primary incubation was withdrawn and transferred to 180 μL of pre-warmed secondary incubation mixture containing of NADPH (1 mM), MgCl2 (3 mM) and probe substrate (3 μM midazolam or 75 μM testosterone) and 0.1 M phosphate buffer (pH 7.4). The secondary incubation mixtures were incubated at 37 °C for 10 min. After which, a 400 μL aliquot of acetonitrile containing camptothecin (internal standard for quantification of 1′-hydroxymidazolam and 6β-hydroxytestosterone) was added to terminate the reactions. The samples were then centrifuged at 4000 × g for 10 min and the resulting supernatants were mixed with an equal volume of water. After vortexing and centrifugation, a 2 μL aliquot of each sample was submitted for LC-MS/MS analysis. Incubations without NADPH in primary incubations were prepared as negative controls.
Approaches for the discovery of drugs that target K Na 1.1 channels in KCNT1-associated epilepsy
Published in Expert Opinion on Drug Discovery, 2022
Barbara Miziak, Stanisław J Czuczwar
When membrane depolarization is persistently present, due to various inactivating mechanisms (e.g. slow cessation of transmission upon activation), the channels go into a non-conducting state. It is important to remember that inactivation is not the same as the reverse process of activation. In inactivation, the stimuli that activate the channel are still present, but the channels no longer conduct ions efficiently [39]. N-type inactivation binds to the intracellular region at the amino-terminal acting, resulting in pore closure. The entire process occurs within a few milliseconds. In case of C-type inactivation, it has been shown to be voltage independent over a range of −25 to +50 mV, and is partially coupled to N-type inactivation. Furthermore, the kinetics of this type of inactivation will vary depending on the alternatively spliced carboxy-terminal regions in the channels involved [40]. C-type inactivation has been shown to play an important role in modulating the firing of action potentials in neurons and cardiac muscle by regulating the availability of functional Kv channels [41].
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