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Alkyl Halides and Substitution Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
A thiol is the sulfur analog of an alcohol and is characterized by a C—S—H bond where the hydrogen atom is acidic (pKa about 10−11). What is the bond polarization for an O—H group?
Biophysical and Biochemical Characterization of Peptide, Protein, and Bioconjugate Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Tapan K. Das, James A. Carroll
The presence of thiols may indicate incompletely formed disulfides in a biotherapeutic protein in which all cysteines are expected to form disulfide bonds. Thiols may be detected using Ellman’s reagent followed by colorimetric detection. Alternatively, thiol-specific chemistry may be used to label free cysteine residues with a chromophore or fluorophore, followed by quantitative detection [59].
Thin-Layer Chromatography in Pharmaceutical Analysis
Published in Bernard Fried, Joseph Sherma, Practical Thin-Layer Chromatography, 2017
Elena Dreassi, Giuseppe Ceramelli, Piero Corti
Ling et al.36 show an application of HPTLC with fluorescence scanning densitometry for the qualitative and quantitative detection of thiols (captopril, coenzyme A, cysteamine, cysteine, glutathione, acetylcysteine), of biological and pharmacological interest, that is difficult to determine with other procedures because of their high reactivity. The mixture of thiols together with their disulfides was first derived with two reagents: ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate (SBD-F) and 7-fluoro-4-sulphamoil-2,1,3-benzoxadiazole (ABD-F) specific for the thiols, followed by elution on HPTLC silica gel plates with a mobile phase composed of isopropionil ether–methanol–water–acetic acid (9:8:2:1, v/v/v/v). The survey is done with an excitation wavelength of 365 nm. Variations of the Rf value obtained with different pH, with the variation of the proportions of acetic acid and of water in the mobile phase, have been observed. Detection limits of the different derivatives of the thiols are about 0.2 pmol. (20–40 pg per spot); for cysteamine-SBD this limit sinks to 6.3 pg. These limits may be lowered further using surfactants (triton, paraffins or cyclodextrin solutions). The calibration curves were linear in the picogram range, with a RSD range of 1.16–3.2% of the complete procedure.
Tolerance and distribution of cadmium in an ornamental species Althaea rosea Cavan
Published in International Journal of Phytoremediation, 2020
Yaping Huang, Lihong Zu, Mei Zhang, Tong Yang, Meili Zhou, Cong Shi, Fuchen Shi, Wenju Zhang
Soluble protein is an important indicator of responding to a wide variety of stress or changes both reversible and irreversible in metabolism (Singh and Tewari 2003; Aibibu et al. 2010). The present study showed that A. rose could increase the tolerance ability of Cd by the accumulation of total soluble protein content (Figure 6). However, the total soluble protein content decreased at 100 mg·kg−1 Cd treatment. This can be associated with the fact that higher accumulated irons load into the leaves and cause greater generation of ROS, which may induce oxidative damage and inhibit protein synthesis (Gupta et al. 2009). Unlike total soluble proteins, NP-SH content increased with the adding of Cd concentration (Figure 6). Tolerance plants have the mechanism that binds heavy metal ions into nontoxicity forms, in addition to the higher ability of synthesizing organic compounds with SH-group (Rauser 1995). Thiols containing the non-proteins, soluble and membrane bound proteins are confirmed to be important in protective reactions (Cobbett 2000). Our study further found from the regression equation that the total soluble proteins and NP-SH content were significantly related to Cd accumulations, which was similar to the result described in Cd hyperaccumulator Rorippa globosa (Sun et al. 2011). Thus, by immobilizing and detoxifying Cd to protect the cells from Cd influx, A. rosea showed a high tolerance to Cd stress.
Studies on the interaction of aquacobalamin with cysteinesulfinic and cysteic acids, hypotaurine and taurine
Published in Journal of Coordination Chemistry, 2018
Ilia A. Dereven’kov, Lubov V. Tsaba, Elizaveta A. Pokrovskaya, Sergei V. Makarov
In vivo thiols are involved in numerous reactions with oxidants. These reactions lead to the formation of disulfides, sulfenic, sulfinic and sulfonic acids [29, 30]. One of the most ubiquitous in nature oxo-derivatives of thiols is taurine (Tau; Figure 1D), which is the product of oxidation of hypotaurine (HTau; Figure 1E), a decarboxylated counterpart of cysteinesulfinic acid (CySO2−; Figure 1C). Taurine is found in numerous tissues throughout the body and exhibits diverse biological [31] and therapeutic effects [32]. Sulfinic and sulfonic acids, viz., cysteic (cysteinesulfonic; CySO3−; Figure 1B) and cysteinesulfinic acids, taurine and hypotaurine, are the known ligands. It is reported that sulfinates can be bound by metal ions via sulfur or oxygen [33–39], whereas aminosulfonates form N- and O-bound complexes [40–44].
Metal- and nonmetal-catalyzed synthesis of five-membered S,N-heterocycles
Published in Journal of Sulfur Chemistry, 2018
Navjeet Kaur, Nirmala Kumari Jangid, Vivek Sharma
Sensitive, rapid and selective detection of biologically toxic and active molecules is of significant importance in the field of biological, chemical and environmental sciences. Compounds with thiol (–SH) functionality are very important as low-molecular-weight aliphatic thiol-containing amino acid (cysteine) and peptides (glutathione) play important roles in biological systems, while aromatic thiols (thiophenols) are important reagents and possess broad synthetic utility. Aromatic thiols are pollutants and toxic compounds even though they are used as important building blocks in organic synthesis [10].