Chemical Factors
Michael J. Kennish in Ecology of Estuaries Physical and Chemical Aspects, 2019
This nutrient element enters rivers and estuaries in dissolved inorganic form principally as the phosphate anion (PO4) derived from the weathering of rocks and leaching of soils, from domestic and industrial wastewater discharges, and from detergents (via the breakdown of polyphosphates) and fertilizers (Table 11). The concentration of phosphate in waters draining pristine regions is rather low, but the addition of animal and human wastes significantly increases the amount of this anion in many influent systems. Phosphorus also exists in estuaries in dissolved organic and particulate forms, although autotrophs, such as phytoplankton, typically remove and incorporate orthophosphate ions. The orthophosphateions include phosphoric acid (H3PO4) and its dissociation products (H2PO−4, HPO−24, and PO3−4).227
Nonhistone Nuclear Phosphoproteins
Lubomir S. Hnilica in Chromosomal Nonhistone Proteins, 2018
Once a protein or protein fraction is identified as phosphorylated, an attempt may be made to quantitate the degree of phosphorylation. The overall level of phosphorylation may be determined as alkali-labile phosphate. The release of phosphate from proteins by base depends not on hydrolysis, but on β-elimination.17 This procedure is valid if phosphoryl groups are linked to the protein only by phosphoester bonds. Although Schiltz and Sekeris18 have presented evidence for in vitro phosphorylation of lysine and arginine in nuclear proteins, and 3-phosphohistidine and ϵ-phospholysine have been found in histones,18–20 the presence of the P-N bond has not been confirmed in nonhistone nuclear proteins. Therefore, as a method for determining total phosphate content in nonhistone proteins, liberation of phosphate by alkali appears to be valid. The released phosphate is generally measured as 32P-labeled orthophosphate selectively extracted as the phosphomolybdate complex.21 Phosphate may be quantitated colorimetrically after reduction of the molybdate complex with SnCl2.22
Foreword
Richard L. Hilderbrand in The Role of Phosphonates in Living Systems, 2018
Organic compounds of phosphorus play an integral role in the biochemical processes of all living systems. These life processes require orthophosphate (PO4≡) as a primary constituent of nucleic acids, phospholipids, and phosphorylated proteins and carbohydrates. Of equal importance is the use of phosphate to generate high energy phosphate bonds whose energy is either used for synthetic processes or for production of other types of energy. In addition, phosphate provides buffering capacity, imparts solubility in aqueous solutions to organic molecules, precipitates with calcium to form the insoluble hydroxylapatites required in bone, and can provide a high concentration of negative charge within a given molecular dimension.1 Phosphate esters are relatively stable in aqueous solutions at physiological pH but will readily hydrolyze when appropriate enzymes are present. Thus, phosphate is uniquely suited to provide the properties necessary to maintain the mosaic of biochemical reactions occurring within a living organism.
Meta-analysis of the efficacy and safety of sevelamer as hyperphosphatemia therapy for hemodialysis patients
Published in Renal Failure, 2023
Qian Zeng, Yuanlong Zhong, Xiqiu Yu
Patients suffering from CKD experience the progressive deterioration of renal function, with concomitant impairment of dietary P excretion that ultimately contributes to hyperphosphatemia in individuals with advanced disease (CKD G3-G5D) [4]. The use of oral P binders and the restriction of dietary orthophosphate intake can slow cardiovascular disease and vascular calcification in CKD patients, contributing to improved prognostic outcomes and survival [5]. Avoiding the use of Ca-based P binders can mitigate the potential risks associated with excessive Ca load, including cardiovascular event incidence and more rapid vascular calcification, spurring interest in the development of non-Ca-based P binders including lanthanum carbonate (LC), sevelamer, and iron-based P binders [6]. According to the 2017 KDIGO guidelines, excessive Ca-based P binder exposure can contribute to worse patient outcomes irrespective of GFR category, although evidence regarding the superiority of Ca-free binders as a means of preventing adverse clinical outcomes remains somewhat controversial, and the most optimal means of balancing the potential for adverse clinical outcomes against treatment-related costs and potential harm remains debatable [7,8].
Discovery of a fragment hit compound targeting D-Ala:D-Ala ligase of bacterial peptidoglycan biosynthesis
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Matic Proj, Martina Hrast, Gregor Bajc, Rok Frlan, Anže Meden, Matej Butala, Stanislav Gobec
The fragment library was assayed in a DdlB inhibition assay, where fragments were tested for their ability to inhibit the D-Ala-adding activity of DdlB ligase. The orthophosphate formed during the enzymatic reaction was measured spectrophotometrically using malachite green reagent. The tested fragment concentrations varied from 1.5 to 5 mM. The criteria for classifying a fragment as a hit were: <50% residual DdlB activity and solubility (low background absorbance of the compound at 650 nm). The results are provided in a Supplementary excel file. We re-purchased six hit compounds that matched the criteria to determine the inhibition of DdlB from freshly prepared compound solutions (Table 2). However, only two hits showed sufficient inhibition for IC50 determination (3 and 4).
Stress, Coping, Resilience and Trust during the Flint Water Crisis
Published in Behavioral Medicine, 2020
Joanne Sobeck, Joanne Smith-Darden, Megan Hicks, Poco Kernsmith, Paul E. Kilgore, Lara Treemore-Spears, Shawn McElmurry
In 2014, the City of Flint, Michigan changed its source of drinking water from Lake Huron treated by the Detroit Water System, to locally treated water from the Flint River. This change in water source brought public and widespread attention because the change of the water system was in response to the Flint’s financial crisis, not for health reasons. Following the water change, corrosion-control practices including the use of orthophosphate, a common corrosion inhibitor, were not correctly implemented, reportedly an additional cost saving measure.3,4 As a result, pipes in the distribution system as well as residential homes began to corrode, releasing iron and lead into the water supply. Within a month of the switch, Flint residents started to report various water odors, changes in color to their water supply, along with documented rashes, hair loss and other health problems.5 Subsequent to these reports, numerous complaints from residents regarding the quality of water were reported to the local government, however, these complaints were ignored.
Related Knowledge Centers
- Chemistry
- Cyclic Compound
- Organic Chemistry
- Oxygen
- Phosphorus
- Oxidation State
- Side Chain
- Hydrogen
- Hydroxy Group
- Ion