Laboratory Procedures and Management
Jeremy R. Jass in Understanding Pathology, 2020
The solution into which tissue samples are placed usually includes formaldehyde. First introduced in 1893 (Bracegirdle, 1993), formaldehyde penetrates tissues rapidly and alters the structure of molecules so that all biological activity is destroyed. In particular, enzymes are denatured. This is important, because dying tissues would normally release their own enzymes and digest themselves, a process called autolysis. Dying tissues are also colonised by bacteria, but these are also destroyed by formaldehyde. Formaldehyde thereby preserves normal cellular structure and acts as a mordant, i.e. it facilitates the subsequent staining of the tissues with dyes. The entire process is called tissue fixation (since it attempts to ‘fix’ tissue in a lifelike state) and takes a few hours to a day or two, depending on the size of the specimen. Fixation can be speeded up by microwaving the tissue.
Potential Significance of Proteases
Hafiz Ansar Rasul Suleria, Megh R. Goyal, Masood Sadiq Butt in Phytochemicals from Medicinal Plants, 2019
Enzymes are protein in nature that accelerate the biochemical reactions as per life processes, which are essential, including respiration, digestion, maintenance of tissues, and metabolism. They have an ability to remove or add atoms to a molecule, join together smaller molecules, and split a large molecule into smaller ones. In other words, they are highly specific biological catalysts. Enzymes have the ability to work under more or less mild conditions and they become superlative or ideal catalyst to be used in food technology.15 Enzymes catalyze many biochemical reactions needed to sustain the life and present in all living organisms. They are metabolized and broken down after intake similar to other proteins of diet. Enzymes are believed to be naturally safe and considered as nontoxic.17
Coagulation Theory, Principles, and Concepts
Harold R. Schumacher, William A. Rock, Sanford A. Stass in Handbook of Hematologic Pathology, 2019
The enzymes of coagulation are generally serine proteases (proteins which catalyze the modification of other proteins by breaking the links which hold a protein together). The term refers to the fact that each has a serine (an amino acid) present in what is referred to as the active site. Most of the proteases of coagulation are based on the structure of trypsin, the protease found in the stomach. The ability to obtain specificity is related to the remaining structure of the enzyme. Thus, the reason a particular coagulation protease does not “chew up” all proteins is due to its three-dimensional structure. Although there is considerable specificity demonstrated by the coagulation proteases, several are noted for their ability to catalyze the hydrolysis of proteins other than their classic substrates.
Inhibition of Echis ocellatus venom metalloprotease by flavonoid-rich ethyl acetate sub-fraction of Moringa oleifera (Lam.) leaves: in vitro and in silico approaches
Published in Toxin Reviews, 2022
Akindele Oluwatosin Adeyi, Kaosarat Keji Mustapha, Babafemi Siji Ajisebiola, Olubisi Esther Adeyi, Damilohun Samuel Metibemu, Raphael Emuebie Okonji
The effects of temperature on enzyme activity were carried out between 30 °C and 100 °C. The assay mixture was first incubated at the selected temperature for 10 min before the reaction was initiated by the addition of 50 µl enzyme that had been incubated at the same temperature. For heat stability of the enzyme, an aliquot of the enzyme was taken and incubated at temperatures of 40, 50, 60, 70, and 80 °C for a period of 1 h and at intervals of 10 min, the enzyme was taken and assayed for residual activity. The effect of pH on metalloproteinase activity was assayed at different pH values. The pH values were varied by using buffers of different pH, which includes 0.01 M citrate buffer (pH 3.0–5.0), 0.01 M Phosphate buffer (pH 6.0–7.0), 1 mM Tris buffer (pH 8.0) and borate buffer (pH 9.0–10.0). Reaction mixture each contained 1 mM of a different buffer, 0.33 M of arginine, and 0.05 ml of the enzyme (Lee et al.2014).
Multifunctional and stimuli-responsive nanocarriers for targeted therapeutic delivery
Published in Expert Opinion on Drug Delivery, 2021
Many enzymes such as proteases, phospoholipases, glycosidases, etc. are known to be found at the site of tumors, and inflammatory tissues. Substrate of such enzymes can be used as the component of drug delivery system to achieve enzyme mediated drug release at the target tissue. In a recent study, researchers used a metalloproteinases cleavable short peptide as a linker between the surface PEG chains and TAT-functionalized liposomes as represented in Figure 7 [34,134,135]. After cleavage of this linker, loaded drugs and bioactive agents were exposed to the target site as compared to that of nanocarriers without such linker. Such nanocarriers systems were used for siRNA delivery showing almost 70% gene-silencing activity in tumor-bearing mice [136,137,138]. In another recent study, Zhang et al. designed a mesoporous silica nanoparticle by grafting hyaluronic acid (HA) as a targeting moiety on its surface via biotin–streptavidin interaction for enzyme triggered delivery of doxorubicin (MSN-HA/Dox). A schematic outline showing MSN-HA/Dox nanoparticle mediated delivery of doxorubicin to cancer cells has been displayed in Figure 8. In vitro results revealed that the release of doxorubicin (Dox) was significantly higher in the presence of enzyme hyaluronidase. MSN-HA/Dox system also displayed increased antitumor effects in vivo as compared to that of the free drug doxorubicin treatment only (Figure 9) [139].
The increasing impact of Chinese innovative drug research on the global stage with a focus on drug discovery
Published in Expert Opinion on Drug Discovery, 2020
Wei Luo, Cherukupalli Srinivasulu, Xia Hao, Xinyong Liu, Peng Zhan
In the human body, each enzyme plays a unique and essential physiological activity. Although its over-expression may cause some diseases, over-inhibition leads to serious side effects. For example, initially, highly selective inhibition of cyclooxygenase-2 (COX-2) was believed to eliminate inflammation without gastrointestinal damage caused by inhibition of COX-1, such as Rofecoxib (1). However, clinical studies have shown that Rofecoxib can cause severe cardiovascular problems after prolonged use due to the highly selective inhibition of COX-2. To avoid the risk of cardiovascular disorders caused by highly selective COX-2 inhibitors, and to prevent gastrointestinal damage caused by significant inhibition of COX-1, Guo Zongru proposed the balanced inhibition strategy of COX-1/COX-2. Based on the known pharmacophore of a COX-2 inhibitor, his research group reported the design and synthesis of a series of compounds with pyrrolidone as core moiety. Among them, Imrecoxib (2), also known as BAP-909, was approved as a balanced COX-1 and COX-2 inhibiting drug with an IC50 value of 91 nM and 15 nM, respectively (Figure 1). In 2005, Imrecoxib was approved by China’s State Food and Drug Administration for the symptomatic treatment of osteoarthritis [8,9].
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