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The Modification of Lysine
Published in Roger L. Lundblad, Chemical Reagents for Protein Modification, 2020
On occasion, the modification of an amino acid residue in a protein is associated with an apparent increase in catalytic activity. This was the situation with the modification of 14S and 30S dynein adenosine triphosphatase activities with trinitrobenzenesulfonic acid.129 In this study, the reaction was performed in 0.030 M barbital, pH 8.5 at 25°C. The extent of modification was determined spectrophotometrically at 345 nm (∊ = 1.45 x 104M−1 cm−1). In studies similar to those obtained with glutamate dehydrogenase as discussed above,124 glutathione reductase was demonstrated to reduce trinitrobenzenesulfonate.130 Inhibition of glutathione reductase was noted at low concentration (0.05 μM) of trinitrobenzenesulfonate.
Cardiac Subcellular Function During Diabetes
Published in Grant N. Pierce, Robert E. Beamish, Naranjan S. Dhalla, Heart Dysfunction in Diabetes, 2019
Grant N. Pierce, Robert E. Beamish, Naranjan S. Dhalla
The final reaction in the sequence of subcellular events leading to a contractile event in the heart ultimately lies with the contractile proteins. Ca2+ binding to the troponin C protein allows myosin to interact with the actin protein through a complex conformational change.1 In the process adenosine triphosphate (ATP) is hydrolyzed to adenosine diphosphate (ADP) and inorganic phosphate (Pi) by the enzyme adenosine triphosphatase (ATPase) which is located on the head region of the myosin molecule.2 The observation that contractile protein ATPase activity could be closely correlated with cardiac muscle function3 has allowed researchers to obtain a biochemical marker of contractile protein function which also has important relevance to muscle performance. It has been conventional to observe the ATPase activity of the various contractile protein fractions in assorted conditions of compromised cardiac contractility in order to determine the extent of involvement of the contractile proteins in this functional defect. However, because of the number of factors which can control contractility at a subcellular level, the contractile protein is not always the culprit in the dysfunction exhibited at a tissue level.
Keratin
Published in Masahiko Mori, Histochemistry of the Salivary Glands, 2019
Myoepithelial cells or basket cells surround acinar cells or intercalated ducts. Enzyme-histochemically, they demonstrate alkaline phosphatase and/or adenosine triphosphatase activities.45 Immunohistochemically, they display myosin or actin proteins as contractive proteins. Immunohistochemically detectable keratins in myoepithelial cells have been identified by recognizing particular keratin polypeptides, and at the same time ductal basal cells are identified (Table 6). A specific keratin antibody for detecting myoepithelial cell has been reported by many authors. The monoclonal antibody stained either myoepithelial cells only, or myoepithelial and ductal basal cells. (Table 6)
Multi-modality management of hypertrophic cardiomyopathy
Published in Hospital Practice, 2023
Shiavax J. Rao, Shaikh B. Iqbal, Arjun S. Kanwal, Wilbert S. Aronow, Srihari S. Naidu
Myosin, the protein that propels the sarcomere and drives muscle contraction, equilibrates between a super relaxed state (with low adenosine triphosphatase [ATPase] activity) and a disordered relaxed state (allowing for interaction with actin) [54]. HCM is characterized by impairment in the energetic and mechanical properties of cardiac myocytes, with recent experimental data suggesting that the resultant hyperdynamic contractility and impaired myocardial relaxation may be due to an imbalance and shift of myosin toward the disordered relaxed state [55–60]. Given these insights, with current limitations of conventional pharmacotherapies and a relatively high threshold for invasive therapies, molecules decreasing the ATPase activity of myosin have emerged as pharmacotherapeutic options targeting the critical pathophysiological mechanism of disease in HCM [61,62].
Crotonaldehyde exposure induces liver dysfunction and mitochondrial energy metabolism disorder in rats
Published in Toxicology Mechanisms and Methods, 2021
Shuman Zhang, Biao Zhang, Qi Zhang, Zhihu Zhang
Mammalian mtDNA encodes the protein subunits of 13 ETC complexes, which are essential for the function of the OXPHOS system, cell function, and biological health (Murphy and Smith 2000). mtDNA is fragile, hence any damage to it results in altered function of mitochondrial OXPHOS (Scheibye-Knudsen et al. 2015; Gustafsson et al. 2016; Van Houten et al., 2016). C V is a key enzyme in ATP synthesis and ATPase6 gene is a subunit of the Fo functional region of the mtDNA encoding C V, which is primarily involved in ATP synthesis. A decrease in ATPase6 gene expression can cause changes in the expression of F0F1 adenosine triphosphatase protein, thereby inducing mitochondrial energy metabolism disorders (Zhang et al. 2010). Real-time PCR showed that crotonaldehyde exposure inhibited the expression of ATPase6 in rat liver mitochondria, which ultimately reduced ATP levels; in addition, crotonaldehyde exposure inhibited the expression of ND1, ND2, Cyt-b, COX1, and COX3 in rat liver mitochondria. These results indicate that crotonaldehyde exposure can disrupt mtDNA transcription, damage the structure and function of liver mitochondria, disturb the mtDNA encoded ETC complex, inhibit the activity of the ETC complex, interfere with energy metabolism, and promote liver damage.
Solid self-nanoemulsifying drug delivery system filled in enteric coated hard gelatin capsules for enhancing solubility and stability of omeprazole hydrochloride
Published in Pharmaceutical Development and Technology, 2020
Suhair S. Al-Nimry, Khouloud A. Alkhamis, Bashar M. Altaani
Omeprazole, 4-methoxy-3, 5-dimethylpyridyl, 5-methoxybenzimidazole derivative of timoprazole, is a proton pump inhibitor. The chemical structure is shown in Scheme 1 (National Center for Biotechnology Information 2016). It is used for the treatment of dyspepsia, gastro-duodenal ulcers, symptomatic gastro-esophageal reflux, and Zollinger-Ellison syndrome (Bozdag et al. 1999; Möschwitzer et al. 2004; El-Badry 2010; Venna et al. 2013; Arshad Ahmed Khan et al. 2015; Singh et al. 2015). It acts by irreversibly blocking the hydrogen/potassium adenosine triphosphatase enzyme system (the H+/K+ ATPase, gastric proton pump) of the gastric parietal cell. The proton pump is responsible for secreting H+ ions into the gastric lumen (Arshad Ahmed Khan et al. 2015; Singh et al. 2015).