China
Africa
Explore chapters and articles related to this topic
Photodynamic Therapy: Membrane and Enzyme Photobiology
Published in Barbara W. Henderson, Thomas J. Dougherty, Photodynamic Therapy, 2020
Tom M. A. R. Dubbelman, Carla Prinsze, Louis C. Penning, John van Steveninck
The photodynamic action of sensitizers upon glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has perhaps been studied in more detail than any other enzyme. The enzyme, isolated from rabbit muscle, contains cysteine moieties and histidines as the most photosensitive amino acids. Inhibition of the enzyme activity by the photodynamic action of hematoporphyrin derivative (HPD) is closely correlated with the oxidation of the SH-group in the active center of the enzyme, but the conformation is also changed, and intermolecular cross-links are formed. This can be shown by several techniques. The intrinsic fluorescence of the protein decreases to about 65% of the original value, without any concomitant decrease of the amount of tryptophan residues; the free energy of isothermal unfolding in urea solutions is increased from 21.2 to 29.5 kJ/mol; and the refolding rate constant of the denatured protein after dilution of the dénaturant is increased from 134 to 309 × 10−5 min−1. An increased susceptibility of proteins to degradation by proteolytic enzymes, as the result of exposure to reactive oxygen species, has been described recently [7]. Photooxidation of GAPDH also increased the susceptibility of the enzyme to the proteolytic attack of elastase. This can be explained by a conformational change exposing previously shielded peptide bonds, enabling enzymatic hydrolysis [8].
Clinical Effects of Pollution
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
According to Samsel and Seneff,939 pancreatic beta cells express extraordinarily high levels of heparin sulfate, which is essential for their survival1003 since it protects them from ROS-induced cell death. As sulfate transport via the hepatic portal vein is likely disrupted by glyphosate, H2S, whether derived from sulfur-containing amino acids or supplied via diffusion following its production by sulfur-reducing bacteria in the gut, can become an important source of sulfur for subsequent sulfate production locally in the pancreatic cells. Pancreatic elastase is a serine protease that is needed to assist in protein degradation but an overabundance can lead to autolysis of tissues.1004 Cholesterol sulfate inhibits pancreatic elastase1004 so a deficiency in cholesterol sulfate supply due to impaired sulfate supply to the liver and impaired CYP function should increase the risk of tissue digestion by pancreatic enzymes, contributing to the loss of villi in the upper small intestine observed in celiac disease and other irritable bowel disease and nonceliac wheat and other food CS.
Natural Products Affecting Biofilm Formation
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Jacqueline Cosmo Andrade Pinheiro, Maria Audilene Freitas, Bárbara de Azevedo Ramos, Luciene Ferreira de Lima, Henrique Douglas Melo Coutinho
Moreover, the microorganism QS inhibitory activity of compounds can also be analyzed to ascertain if the compound of interest is interfering with cellular communication and thus preventing them from being able to “sense” cell density and recruit other cells. The simplest and best-known method for detecting QSI is through the inhibition of violacein produced by Chromobacterium violaceum (Kothari et al. 2017). D’Almeida et al. (2017) showed the efficacy of certain coumarins at inhibiting C. violaceum QS, as well as elastase production in P. aeruginosa, while Asfour (2018) summarizes several naturally occurring compounds with anti-QS activity against Gram-positive and Gram-negative bacteria.
Characterization of Pseudomonas aeruginosa isolated from various environmental niches: New STs and occurrence of antibiotic susceptible “high-risk clones”
Published in International Journal of Environmental Health Research, 2020
Asma Bel Hadj Ahmed, Mohamed Salah Abbassi, Beatriz Rojo-Bezares, Lidia Ruiz-Roldán, Rabii Dhahri, Ines Mehri, Yolanda Sáenz, Abdennaceur Hassen
Elastase activity was determined by the Elastin-Congo-Red assay (Pearson et al. 1997). From a bacterial suspension on LB broth (OD620nm: 0.1–0.15) incubated at 37ºC with shaking at 200 rpm for 24 h, the pyocyanin and pyorubin pigments were extracted and quantified. After adding chloroform and centrifugation at 4,000 rpm for 15 min, pyorubin was recovered from the aqueous phase, and the amount was evaluated by measuring the absorbance at 525 nm. Pyocyanin was extracted from the chloroform phase and subsequent addition of HCl 0.2 N, and was quantified by measuring the absorbance of the solution at 520 nm, based on a calibration curve established with purified pyocyanin (Sigma-Aldrich, St. Louis, MO) (Anantharajah et al. 2017). Colony forming units (CFU)/mL were determined by seeding duplicated serial dilutions on BHI agar. P. aeruginosa PAO1 was used as a control strain in these experiments.