Homeostasis of Dopamine
Nira Ben-Jonathan in Dopamine, 2020
The sulfation reaction is catalyzed by members of the sulfotransferase (SULT) superfamily (Table 1.2). Sulfation is involved in the conjugation of numerous endogenous and xenobiotic chemicals, thus exerting considerable influence over their biological activity [29]. The sulfation reaction entails the enzymatic transfer of a sulfonate group (SO3−1) from a universal donor, 3′-phosphoadenosine, 5′-phosphosulfate, to recipient molecules. Sulfation is a major contributor to the homeostasis and regulation of catecholamines, steroids, and iodothyronines, as well as the detoxication of xenobiotics. SULT enzymes are widely expressed in a variety of human tissues, including liver, intestine, and brain. They are classified on the basis of their substrate specificity and amino acid sequence into two subfamilies: SULT1 (phenol sulfotransferases or PST) and SULT2 (steroid sulfotransferases).
Replicase
Paul Pumpens in Single-Stranded RNA Phages, 2020
The finding on the Qβ replicase inhibition by polyethylene sulfonate was of a special importance. The polyethylene sulfonate at low concentrations inhibited the initiation, but not elongation, of RNA synthesis by Qβ replicase (Kondo and Weissmann 1972b). It allowed in turn the controlled, stepwise synthesis of RNA by the Qβ enzyme (Bandle and Weissmann 1972). The polyethylene sulfonate affected a step subsequent to the primary binding of Qβ RNA to the replicase and prior to the formation of the first few internucleotide bonds. Therefore, if addition of polyethylene sulfonate to the Qβ RNA-directed Qβ replicase reaction after initiation has taken place, it led to the exclusive formation of free, single-stranded minus strands. Moreover, the inhibition by polyethylene sulfonate could be reversed by the addition of an appropriate quantity of protamine sulfate.
Reproductive and Developmental Toxicity Studies by Cutaneous Administration
Rhoda G. M. Wang, James B. Knaak, Howard I. Maibach in Health Risk Assessment, 2017
A surfactant used in food and drug formulations, linear alkylbenzene sulfonate (LAS), was tested experimentally for percutaneous toxicity.65 At concentrations in the range of 0.03 to 3.0%, there was no reported developmental toxicity in mice, rats, or rabbits when LAS was applied over most of gestation. Studies in the rat and mouse were corroborated by other investigators.83,84 Oral studies in rats and rabbits with LAS had similar negative results,85 but oral administration of 300 or 600 mg/kg/d on gestation days 6 to 15 in the mouse by the oral route resulted in the production of skeletal anomalies.85
Bulk phase resource ratio alters carbon steel corrosion rates and endogenously produced extracellular electron transfer mediators in a sulfate-reducing biofilm
Published in Biofouling, 2019
Gregory P. Krantz, Kilean Lucas, Erica L.- Wunderlich, Linh T. Hoang, Recep Avci, Gary Siuzdak, Matthew W. Fields
One of the confirmed dysregulated metabolites, sulfolactate, was increased 15.7-fold under EAL conditions on 1018 steel (Figure 7). Sulfolactate is a sulfonate compound related to the cysteine/methionine processing pathways in some microorganisms. A complete pathway from cysteine to sulfolactate is not predicted in the Desulfovibrio G20 genome whereas the genome is annotated to contain an aminotransferase that could convert cysteate to sulfopyruvate (E.C. 2.6.1.1; KEGG). However, the genome annotation does not contain an identified enzyme to catalyze the conversion of sulfopyruvate to sulfolactate. The commonly identified enzymes with this activity include sulfolactate dehydrogenase (R and S) and malate dehydrogenase and would provide additional electron acceptor (reduction of sulfopyruvate to sulfolactate) via recycling of cysteine through cysteate and could account for the elevated sulfolactate levels that were detected under EAL conditions. The Desulfovibrio G20 genome is annotated to have a gene that encodes a protein with potential malate dehydrogenase activity (Dde1008, NAD+-linked). Sequence comparisons and biochemical studies have recently expanded the functionality of previously annotated malate and lactate dehydrogenases to have other activities such as sulfolactate dehydrogenase (Muramatsu et al. 2005); however, the potential role of Dde1008 in conversion of sulfopyruvate to sulfolactate is unknown.
Targeting the intestinal lymphatic system: a versatile path for enhanced oral bioavailability of drugs
Published in Expert Opinion on Drug Delivery, 2018
Renuka Suresh Managuli, Sushil Yadaorao Raut, Meka Sreenivasa Reddy, Srinivas Mutalik
N′-ethylcarbodiimide (EDC) – N-Hydroxysuccinimide (NHS) coupling is a well-known reaction between –COOH and –NH2 functional groups to form stable amide (–CONH) group. The carbodiimides (water-soluble EDC for aqueous crosslinking and the water-insoluble DCC for non-aqueous organic synthesis methods) are zero-length cross-linkers which activate free carboxylic acid to unstable reactive o-acylisourea intermediate. This carbodiimide coupling reaction is efficient at acidic pH (4.5–5.5) with MES (4-morpholino-ethane-sulfonic acid) buffer; however phosphate buffers (pH ≤ 7.2) are also compatible. N-hydroxysuccinimide (NHS) or its water-soluble analog (Sulfo-NHS) improves the efficiency of reaction by producing a more stable amine reactive NHS ester intermediate. Sulfonate (–SO3) group of NHS has no effect on the reaction chemistry; it only increases the water-solubility of cross-linker. NHS ester reacts with primary amine in slightly alkaline conditions (pH 7.2–8.5) to yield stable amide bonds. NHS-ester crosslinking reactions are usually performed in phosphate buffer at pH 7.2–8.0 for 0.5 to 4 h at room temperature or 4°C. The side products of the reaction can be removed easily by dialysis. External carboxyl and primary amine (such as Tris or glycine) groups, if present in the reaction mixture, compete with the reaction. Therefore, care has to be taken to exclude extraneous reacting groups but when needed they can be used to quench the reaction. Figure 2 depicts the EDC-NHS reaction between carboxyl/amine functionalized nanoparticle and RGD peptide as a model ligand.
Xenobiotic C-sulfonate derivatives; metabolites or metabonates?
Published in Xenobiotica, 2018
Stephen C. Mitchell
In the 1970s reports appeared stating that the major urinary metabolite obtained following the topical application to rats, rabbits and pigs of 2-pyridinethiol-1-oxide (2-mercaptopyridine N-oxide; pyrithione) (Shaw et al., 1950), an antimicrobial agent, was pyridine-N-oxide-2-sulfonic acid (Howlett & Van Abbe, 1975; Min et al., 1970; Wedig et al., 1978). This sulfonic acid was also present in the urine of pigs following intravenous administration (Adams et al., 1976) and detected in rabbit tissues following dermal application (Howlett & Van Abbe, 1975). However, with this compound the sulfur atom was already bonded to a carbon of the pyridine ring before administration and the sulfonic acid metabolite identified was a product of extensive oxygenation of this preexisting sulfur atom and not the result of the addition of a sulfonate group. It was suggested that the dimerization product, 2,2′-(pyridyl-N-oxide) disulfide, identified as a metabolite, was oxidized via the disulfoxide to the disulfone and finally cleaved to yield the sulfonic acid (Figure 1) (Min et al., 1970). Similar pathways have been advocated for glutathione disulfide (Schröder & Eaton, 2009).
Related Knowledge Centers
- Acid
- Ester
- Functional Group
- Sulfonic Acid
- Organosulfur Chemistry
- Salt
- Conjugate
- Redox
- Ion
- Scandium(Iii) Trifluoromethanesulfonate