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Structural Organization of the Liver
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Lysosomes are defined as organelles specialized for intracellular digestion. They contain a wide variety of hydrolytic enzymes called acid hydrolases because they operate best at an acidic pH (about 5). Although it is simple to define lysosomes conceptually, it is difficult to identify them morphologically because they are highly pleomorphic. Lysosomal content may be homogeneous or heterogeneous and may include dense pigments, myelin figures, or partially digested organelles (Figure 20). Their positive identification in electron micrographs requires that the organelle be bound by a single membrane and show a positive histochemical reaction for acid phosphatase, a representative acid hydrolase (Bainton, 1981; deDuve, 1969, 1975; Novikoff et al., 1956; Novikoff, 1973). In addition, histochemistry has identified a region of SER and Golgi complex rich in acid phosphatase (Novikoff and Yam, 1978). It is thought that lysosomal enzymes synthesized in the RER and transported to the SER are subsequently transferred to the Golgi complex, where the enzymes are modified and packaged as lysosomes (Hasilik, 1980). The aforementioned group of acid-phosphatase-rich organelles (the Golgi complex, ER and lysosomes) has been called GERL (Novikoff and Yam, 1978).
Using a Recombinant Metagenomic Lipase for Enantiomeric Separation of Pharmaceutically Important Drug Intermediates
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Rakesh Kumar, Uttam Chand Banerjee, Jagdeep Kaur
Enzymes are natural catalysts that facilitate the majority of the reactions occurring in biological systems. Use of natural catalysts (enzymes) for chemical processes is referred to as “white biotechnology” (Giovanni, 2003; Walsh, 2001). Natural catalysts are required in small amounts compared with chemical catalysts and can replace relatively dangerous chemicals and save resources (Jaeger, 2004; Patel, 2003; Panke et al., 2004). Currently, the biotechnological potential of hydrolytic enzymes is of special interest. Among these, lipases provide new and innovative biotechnological solutions, which in turn increase efficiency and productivity for manufacturers. They are a familiar valuable biocatalyst in food, pharmaceutical, detergent, and chemical industries. Lipase-catalyzed reactions have received much attention in recent years, as they successfully catalyze interesterification, acidolysis, esterification, alcoholysis, and aminolysis in addition to its hydrolytic activity on triglycerides (Guncheva et al., 2011; Kourist et al., 2010).
Neuropathology of Drugs of Dependence
Published in S.J. Mulé, Henry Brill, Chemical and Biological Aspects of Drug Dependence, 2019
L. Roizin, M. Halpern, M. M. Baden, M. Kaufman, S. Hashimoto, J. C. Liu, B. Eisenberg
Histochemical and electron microscopic investigations reveal that the drugs are bound in the tissues in a diversified distribution and concentration and that adverse and toxic drug reactions are associated with changes of the (a) hydrolytic enzyme systems, (b) fine ultrastructural alterations of the ultracellular organelles, (c) communication or transport mechanisms in the CNS (particularly the synaptic complex and axonal flow), and (d) membrane permeability (including brain-blood barrier).
Biotherapeutic effect of cell-penetrating peptides against microbial agents: a review
Published in Tissue Barriers, 2022
Idris Zubairu Sadiq, Aliyu Muhammad, Sanusi Bello Mada, Bashiru Ibrahim, Umar Aliyu Umar
Protein-derived peptides are peptides that are often derived from proteins, which may originate from natural sources such as plants, animals, or microorganisms (bacteria, yeast, and fungi). These protein-derived peptides are usually obtained from enzyme hydrolysis, fermentation, or digestion.19 Hydrolytic enzymes are commonly used to digest these proteins from a variety of sources, after which the bioactivity of the entire crude extract is assessed, followed by a series of activity-guided purification and identification to determine the most appropriate sequence.15,20 A peptide generated from the prion protein with a hydrophobic sequence was demonstrated to have powerful antiprion effects in prion-infected cells by reducing the pathogenic scrapie isoform crucial for prion pathogenicity.21 A research utilized both an in silico and an experimental technique to find protein-derived CPPs by extracting arginine-rich peptide segments from SwissProt proteins and analyzing their cell-penetrating capabilities.22 A study revealed multiple unique human-protein-derived CPPs employing a combination of in silico and experimental methods. Twenty of the sixty peptides tested were found to be functional, with the neurturin peptide performing best across the peptides screened.23
Insights into the activation of oral keratinocyte cell death by Candida albicans and Staphylococcus aureus biofilms
Published in Biofouling, 2021
Kassia de Carvalho Dias, Paula Aboud Barbugli, Carlos Eduardo Vergani
Candida species, which are opportunistic pathogens that belong to the microbiota of healthy individuals, are prevalent in the mucous membranes of the gastrointestinal tract, esophagus, mouth and vagina, and can colonize different anatomical sites (Kim and Sudbery 2011; Paiva et al. 2012). The pathogenicity of C. albicans is influenced by several virulence factors related to host tissue adhesion capacity, secretion of hydrolytic enzymes (proteases, phospholipases and hemolysins) and biofilm formation capacity (Sardi et al. 2013). Extracellular hydrolytic enzymes are virulence factors that also play an important role in microbial adhesion and promote the destruction of host tissues (Zago et al. 2015). It has been reported that C. albicans is capable of secreting Aspartic Proteinase Isoenzymes (SAPs) 4, 5 and 6 and induce epithelial cell apoptosis by the Trojan horse mechanism (Wu et al. 2013).
Emerging roles of autophagy in the development and treatment of urothelial carcinoma of the bladder
Published in Expert Opinion on Therapeutic Targets, 2021
Pratishtha Gupta, Niraj Kumar, Minal Garg
Autophagy represents a powerful survival strategy for cells that are exposed to cell-intrinsic or environmental stressful stimuli. Autophagy is a tightly regulated physiologic catabolic process, which allows the cells to cope up under stress conditions (nutritional, metabolic, oxidative, pathogenic, genotoxic, and proteotoxic stress) and restores homeostasis [18]. The complex process of autophagy is a four-step process that involves (i) activation and elongation, (ii) maturation, (iii) lysosome fusion, and (iv) degradation. It serves an important function to degrade and recycle the damaged cytoplasmic components like organelles and macromolecules. It initiates with the progressive segregation of cytoplasmic proteins and organelles. They are then swallowed up by double membrane vesicles known as autophagosomes. Autophagosomes fuse with lysosomes to form autolysosomes. Hydrolytic enzymes in the acidic environment in autolysosomes digest the internalized cellular biomass, eliminate toxins, and facilitate a host of favorable nutrient and growth conditions (Figure 1) [26].