Commonly used disinfectants in Tanzania

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Genetic and Metabolic Controls for Sulfate Metabolism in \u3cem\u3eNeurospora crassa\u3c/em\u3e: Isolation and Study of Chromate-Resistant and Sulfate Transport-Negative Mutants

Mutants of Neurospora resistant to chromate were selected and all were found to map at a single genetic locus designated as cys-13. The chromate-resistant mutants grow at a wild-type rate on minimal media but are partially deficient in the transport of inorganic sulfate, especially during the conidial stage. An unlinked mutant, cys-14, is sensitive to chromate but transports sulfate during the mycelial stage at only 25% of the wild-type rate; cys-14 also grows at a fully wild-type rate on minimal media. The double-mutant strain, cys-13;cys-14, cannot utilize inorganic sulfate for growth and completely lacks the capacity to transport this anion. The only biochemical lesion that has been detected for the double-mutant strain is its loss in capacity for sulfate transport. Neurospora appears to possess two distinct sulfate permease species encoded by separate genetic loci. The transport system (permease I) encoded by cys-13 predominates in the conidial stage and is replaced by sulfate permease II, encoded by the cys-14 locus, during outgrowth into the mycelial phase. The relationship of these new mutants to cys-3, a regulatory gene that appears to control their expression, is discussed

Redox regulation of type-I inositol trisphosphate receptors in intact mammalian cells.

A sensitization of inositol 1,4,5-trisphosphate receptor (IP3R)-mediated Ca2+ release is associated with oxidative stress in multiple cell types. These effects are thought to be mediated by alterations in the redox state of critical thiols in the IP3R, but this has not been directly demonstrated in intact cells. Here, we utilized a combination of gel-shift assays with MPEG-maleimides and LC-MS/MS to monitor the redox state of recombinant IP3R1 expressed in HEK293 cells. We found that under basal conditions, ∼5 of the 60 cysteines are oxidized in IP3R1. Cell treatment with 50 μm thimerosal altered gel shifts, indicating oxidation of ∼20 cysteines. By contrast, the shifts induced by 0.5 mm H2O2 or other oxidants were much smaller. Monitoring of biotin-maleimide attachment to IP3R1 by LC-MS/MS with 71% coverage of the receptor sequence revealed modification of two cytosolic (Cys-292 and Cys-1415) and two intraluminal cysteines (Cys-2496 and Cys-2533) under basal conditions. The thimerosal treatment modified an additional eleven cysteines, but only three (Cys-206, Cys-767, and Cys-1459) were consistently oxidized in multiple experiments. H2O2 also oxidized Cys-206 and additionally oxidized two residues not modified by thimerosal (Cys-214 and Cys-1397). Potentiation of IP3R channel function by oxidants was measured with cysteine variants transfected into a HEK293 IP3R triple-knockout cell line, indicating that the functionally relevant redox-sensitive cysteines are predominantly clustered within the N-terminal suppressor domain of IP3R. To our knowledge, this study is the first that has used proteomic methods to assess the redox state of individual thiols in IP3R in intact cells. © 2018 Joseph et al

The Effects of Cocaine on Different Redox Forms of Cysteine and Homocysteine, and on Labile, Reduced Sulfur in the Rat Plasma Following Active versus Passive Drug Injections

Received: 28 November 2012 / Revised: 19 April 2013 / Accepted: 6 May 2013 / Published online: 16 May 2013 The Author(s) 2013. This article is published with open access at Springerlink.comThe aim of the present studies was to evaluate cocaine-induced changes in the concentrations of different redox forms of cysteine (Cys) and homocysteine (Hcy), and products of anaerobic Cys metabolism, i.e., labile, reduced sulfur (LS) in the rat plasma. The above-mentioned parameters were determined after i.p. acute and subchronic cocaine treatment as well as following i.v. cocaine self-administration using the yoked procedure. Additionally, Cys, Hcy, and LS levels were measured during the 10-day extinction training in rats that underwent i.v. cocaine administration. Acute i.p. cocaine treatment increased the total and protein-bound Hcy contents, decreased LS, and did not change the concentrations of Cys fractions in the rat plasma. In turn, subchronic i.p. cocaine administration significantly increased free Hcy and lowered the total and protein-bound Cys concentrations while LS level was unchanged. Cocaine self-administration enhanced the total and protein-bound Hcy levels, decreased LS content, and did not affect the Cys fractions. On the other hand, yoked cocaine infusions did not alter the concentration of Hcy fractions while decreased the total and protein-bound Cys and LS content. This extinction training resulted in the lack of changes in the examined parameters in rats with a history of cocaine self-administration while in the yoked cocaine group an increase in the plasma free Cys fraction and LS was seen. Our results demonstrate for the first time that cocaine does evoke significant changes in homeostasis of thiol amino acids Cys and Hcy, and in some products of anaerobic Cys metabolism, which are dependent on the way of cocaine administration

Pichia pastoris Fep1 is a [2Fe-2S] protein with a Zn finger that displays an unusual oxygen-dependent role in cluster binding

Fep1, the iron-responsive GATA factor from the methylotrophic yeast Pichia pastoris, has been characterised both in vivo and in vitro. This protein has two Cys(2)-Cys(2) type zinc fingers and a set of four conserved cysteines arranged in a Cys-X-5-Cys-X-8-Cys-X-2-Cys motif located between the two zinc fingers. Electronic absorption and resonance Raman spectroscopic analyses in anaerobic and aerobic conditions indicate that Fep1 binds iron in the form of a [2Fe-2S] cluster. Site-directed mutagenesis shows that replacement of the four cysteines with serine inactivates this transcriptional repressor. Unexpectedly, the inactive mutant is still able to bind a [2Fe-2S] cluster, employing two cysteine residues belonging to the first zinc finger. These two cysteine residues can act as alternative cluster ligands selectively in aerobically purified Fep1 wild type, suggesting that oxygen could play a role in Fep1 function by causing differential localization of the [Fe-S] cluster

Replacement of the Catalytic Nucleophile Aspartyl Residue of Dextran Glucosidase by Cysteine Sulfinate Enhances Transglycosylation Activity

Dextran glucosidase from Streptococcus mutans (SmDG) catalyzes the hydrolysis of an α-1,6-glucosidic linkage at the nonreducing end of isomaltooligosaccharides and dextran. This enzyme has an Asp-194 catalytic nucleophile and two catalytically unrelated Cys residues, Cys-129 and Cys-532. Cys-free SmDG was constructed by replacement with Ser (C129S/C532S (2CS), the activity of which was the same as that of the wild type, SmDG). The nucleophile mutant of 2CS was generated by substitution of Asp-194 with Cys (D194C-2CS). The hydrolytic activity of D194C-2CS was 8.1 × 10⁻⁴ % of 2CS. KI-associated oxidation of D194C-2CS increased the activity up to 0.27% of 2CS, which was 330 times higher than D194C-2CS. Peptide-mapping mass analysis of the oxidized D194C-2CS (Ox-D194C-2CS) revealed that Cys-194 was converted into cysteine sulfinate. Ox-D194C-2CS and 2CS shared the same properties (optimum pH, pI, and substrate specificity), whereas Ox-D194C-2CS had much higher transglucosylation activity than 2CS. This is the first study indicating that a more acidic nucleophile (-SOO−) enhances transglycosylation. The introduction of cysteine sulfinate as a catalytic nucleophile could be a novel approach to enhance transglycosylation

キイロショウジョウバエ由来のチオレドキシン還元酵素のC未端テトラペプチド配列は、ヒト肺由来のチオレドキシン還元酵素では酸化還元活性を示さない

The isozymes of mammalian thioredoxin reductase (TrxR) contain the penultimate selenocysteineresidue (SeCys) in the redox-active C-terminal tetrapeptide, -Gly-Cys-SeCys-Gly (end). Amutant form of the mammalian enzyme TrxR-X498C in which SeCys is replaced with Cys showsa dramatically decreased catalytic activity, suggesting that SeCys residue plays an integral role inthe catalysis. In contrast, TrxR of the fruit fly, Drosophila melanogaster, has no selenium in the corresponding C-terminal redox sequence, which instead of SeCys has flanking serine residues in the terminal sequence, -Ser-Cys-Cys-Ser (end). Because the catalytic activity of Dm-TrxR is comparable to that of the mammalian selenoenzyme, we introduced the serine residues at the corresponding positions of the recombinant TrxR-X498C and mimicked the redox center of the fruit fly TrxR. However, the catalysis remained as low as the Cys mutant of the selenoenzyme, suggesting that the additional structural features are still required for the tetrapeptide to function as a redox center. MOPAC calculation suggested that the complete motif might involve the hexapeptide sequence, which includes a proline residue, -Pro-X-Ser-Cys-Cys-Ser (end). The proline-containing motif is conserved among other insect TrxRs such as those of honeybee and fruit fly.ほ乳類チオレドキシン還元酵素はＣ末端配列-Gly-Cys-SeCys-Gly（end）の後ろから２番目にセレノシステイン（SeCys）残基を持つ．SeCys をシステインに変換すると酵素の活性は大きく低下するので，SeCys 残基が触媒活性に必須であることが分かる．これに対してキイロショウジョウバエのチオレドキシン還元酵素（Dm-TrxR）のＣ末端配列にはセレンが含まれず，システイン残基の対が２つのセリンに挟まれた配列-Ser-Cys-Cys-Ser (end）を持つ．それでも Dm-TrxR はほ乳類のセレン含有酵素と同程度の触媒能を示す．われわれはヒト肺チオレドキシン還元酵素に Dm-TrxR のＣ末端テトラペプチド配列を導入してその効果を調べた．しかし，酵素活性はまったく上昇せず，Dm-TrxR のＣ末端のテトラペプチド配列-Ser-Cys-Cys-Ser だけでは Cys 残基のチオール基を活性化する効果はなかった．そこで，分子軌道計算 MOPAC を用いて酸化還元機能を担うためのＣ末端配列モチーフを探索した．その結果，テトラペプチドにさらに２つ先のプロリンまでを含めた Pro-X-Ser-Cys-Cys-Ser（end）により初めて酸化還元モチーフとして機能する可能性が示唆された．Pro を含むこの配列モチーフはミツバチや蚊などほかの昆虫の TrxR でも保存されてい

Crystal Structure of the Cysteine-Rich Domain of Mannose Receptor Complexed with a Sulfated Carbohydrate Ligand

The macrophage and epithelial cell mannose receptor (MR) binds carbohydrates on foreign and host molecules. Two portions of MR recognize carbohydrates: tandemly arranged C-type lectin domains facilitate carbohydrate-dependent macrophage uptake of infectious organisms, and the NH2-terminal cysteine-rich domain (Cys-MR) binds to sulfated glycoproteins including pituitary hormones. To elucidate the mechanism of sulfated carbohydrate recognition, we determined crystal structures of Cys-MR alone and complexed with 4-sulfated-N-acetylgalactosamine at 1.7 and 2.2 Å resolution, respectively. Cys-MR folds into an approximately three-fold symmetric β-trefoil shape resembling fibroblast growth factor. The sulfate portions of 4-sulfated-N-acetylgalactosamine and an unidentified ligand found in the native crystals bind in a neutral pocket in the third lobe. We use the structures to rationalize the carbohydrate binding specificities of Cys-MR and compare the recognition properties of Cys-MR with other β-trefoil proteins

In Vivo Imaging of Transplanted Islets with ^(64)Cu-DO3A-VS-Cys^(40)-Exendin-4 by Targeting GLP-1 Receptor

Glucagon-like peptide 1 receptor (GLP-1R) is highly expressed in pancreatic islets, especially on β-cells. Therefore, a properly labeled ligand that binds to GLP-1R could be used for in vivo pancreatic islet imaging. Because native GLP-1 is degraded rapidly by dipeptidyl peptidase-IV (DPP-IV), a more stable agonist of GLP-1 such as Exendin-4 is a preferred imaging agent. In this study, DO3A-VS-Cys^(40)-Exendin-4 was prepared through the conjugation of DO3A-VS with Cys^(40)-Exendin-4. The in vitro binding affinity of DO3A-VS-Cys^(40)-Exendin-4 was evaluated in INS-1 cells, which overexpress GLP-1R. After ^(64)Cu labeling, biodistribution studies and microPET imaging of ^(64)Cu-DO3A-VS-Cys^(40)-Exendin-4 were performed on both subcutaneous INS-1 tumors and islet transplantation models. The subcutaneous INS-1 tumor was clearly visualized with microPET imaging after the injection of ^(64)Cu-DO3A-VS-Cys^(40)-Exendin-4. GLP-1R positive organs, such as pancreas and lung, showed high uptake. Tumor uptake was saturable, reduced dramatically by a 20-fold excess of unlabeled Exendin-4. In the intraportal islet transplantation models, ^(64)Cu-DO3A-VS-Cys^(40)-Exendin-4 demonstrated almost two times higher uptake compared with normal mice. ^(64)Cu-DO3A-VS-Cys^(40)-Exendin-4 demonstrated persistent and specific uptake in the mouse pancreas, the subcutaneous insulinoma mouse model, and the intraportal human islet transplantation mouse model. This novel PET probe may be suitable for in vivo pancreatic islets imaging in the human

Sulfur amino acid requirements of broilers from two to five weeks of age

Phase-feeding (PF) in broiler chickens has been researched as a way to reduce feed costs without reducing growth performance and yield. Predicted amino acid requirements for PF are generated using linear regression equations derived from best estimates of lysine (Lys), sulfur amino acid (SAA), and threonine (Thr) requirements. During the late starter and early grower periods, predicted requirements for the SAA methionine (Met) and cysteine (Cys) are higher than levels recommended by the National Research Council (NRC), and previous research suggests that SAA may be lowered during the grower period without sacrificing growth performance or yield. The objective of this study was to estimate Met and Cys requirements for broilers from 2 to 5 weeks of age. In Experiment 1, a Met-deficient corn-peanut meal diet was formulated to contain excess Cys, so that supplemental Met was not utilized for Cys synthesis. The basal diet for Experiment 2 met the Met requirement but was deficient in Cys. Graded levels of Met (0, 0.045, 0.09, 0.135, and 0.225%) and Cys (0, 0.035, 0.070, 0.105, 0.140, 0.175%) were added in Experiments 1 and 2, respectively, and diets were fed to five replicates of five broilers per pen. Broken-line analysis was used to estimate SAA requirements. The digestible Met and Cys requirements from 2 to 5 weeks of age were 0.33% and 0.31%, respectively. Requirement estimates were lower than those predicted by PF or recommended by NRC, indicating that lower SAA levels may be utilized in a PF progra