scholarly journals Cover Feature: A Facile Method for the Separation of Methionine Sulfoxide Diastereomers, Structural Assignment, and DFT Analysis (Chem. Eur. J. 20/2020)

2020 ◽  
Vol 26 (20) ◽  
pp. 4433-4433
Author(s):  
Jevgenij A. Raskatov ◽  
Scott Virgil ◽  
Hsiau‐Wei Lee ◽  
Lawrence M. Henling ◽  
Ka Chan ◽  
...  
Keyword(s):  
Methionine Sulfoxide ◽  
Structural Assignment

scholarly journals A Facile Method for the Separation of Methionine Sulfoxide Diastereomers, Structural Assignment, and DFT Analysis

2020 ◽  
Vol 26 (20) ◽  
pp. 4467-4470 ◽  
Author(s):  
Jevgenij A. Raskatov ◽  
Scott Virgil ◽  
Hsiau‐Wei Lee ◽  
Lawrence M. Henling ◽  
Ka Chan ◽  
...  
Keyword(s):  
Methionine Sulfoxide ◽  
Structural Assignment

Synthesis and Reactivity of Precolibactin 886

2019 ◽  
Author(s):  
Seth Herzon ◽  
Alan R. Healy ◽  
kevin wernke ◽  
Chung Sub Kim ◽  
Nicholas Lees ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Gene Cluster ◽  
Amino Alcohol ◽  
Biomimetic Synthesis ◽  
Cross Linking ◽  
E Coli ◽  
Hplc Purification ◽  
Structural Assignment ◽  
Biosynthetic Precursor ◽  
Double Oxidation

<div>The clb gene cluster encodes the biosynthesis of metabolites known as precolibactins and colibactins. The clb pathway is found in gut commensal E. coli, and clb metabolites are thought to initiate colorectal cancer via DNA cross-linking. Precolibactin 886 (1) is one of the most complex isolated clb metabolites; it contains a 15-atom macrocycle and an unusual 5-hydroxy-3-oxazoline ring. Here we report confirmation of the structural assignment via a biomimetic synthesis of precolibactin 886 (1) proceeding through the amino alcohol 9. Double oxidation of 9 afforded the unstable α-ketoimine 2 which underwent macrocyclization to precolibactin 886 (1) upon HPLC purification (3% from 9). Studies of the putative precolibactin 886 (1) biosynthetic precursor 2, the model α-ketoimine 25, and the α-dicarbonyl 26 revealed that these compounds are susceptible to nucleophilic rupture of the C36–C37 bond. Moreover, cleavage of 2 produces other known clb metabolites or biosynthetic intermediates. This unexpected reactivity explains the difficulties in isolating full clb metabolites and accounts for the structure of a recently identified colibactin–adenine adduct. The colibactin peptidase ClbP deacylates synthetic precolibactin 886 (1) to form a non-genotoxic pyridone, suggesting precolibactin 886 (1) lies off-path of the major biosynthetic route.</div>

Synthesis and structural assignment of novel 5'-epimeric 3'-deoxy-3',4'-didehydronucleoside-5'-C-phosphonates

2011 ◽  
Author(s):  
Magdalena Petrová ◽  
Miloš Buděšínský ◽  
Blanka Klepetářová ◽  
Ivan Rosenberg
Keyword(s):  
Structural Assignment

scholarly journals The Function of Selenium in Central Nervous System: Lessons from MsrB1 Knockout Mouse Models

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1372
Author(s):  
Tengrui Shi ◽  
Jianxi Song ◽  
Guanying You ◽  
Yujie Yang ◽  
Qiong Liu ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Synaptic Plasticity ◽  
Mouse Model ◽  
Mouse Models ◽  
Knockout Mouse ◽  
Methionine Sulfoxide ◽  
Methionine Sulfoxide Reductase ◽  
Knockout Mouse Model ◽  
The Central Nervous System

MsrB1 used to be named selenoprotein R, for it was first identified as a selenocysteine containing protein by searching for the selenocysteine insert sequence (SECIS) in the human genome. Later, it was found that MsrB1 is homologous to PilB in Neisseria gonorrhoeae, which is a methionine sulfoxide reductase (Msr), specifically reducing L-methionine sulfoxide (L-Met-O) in proteins. In humans and mice, four members constitute the Msr family, which are MsrA, MsrB1, MsrB2, and MsrB3. MsrA can reduce free or protein-containing L-Met-O (S), whereas MsrBs can only function on the L-Met-O (R) epimer in proteins. Though there are isomerases existent that could transfer L-Met-O (S) to L-Met-O (R) and vice-versa, the loss of Msr individually results in different phenotypes in mice models. These observations indicate that the function of one Msr cannot be totally complemented by another. Among the mammalian Msrs, MsrB1 is the only selenocysteine-containing protein, and we recently found that loss of MsrB1 perturbs the synaptic plasticity in mice, along with the astrogliosis in their brains. In this review, we summarized the effects resulting from Msr deficiency and the bioactivity of selenium in the central nervous system, especially those that we learned from the MsrB1 knockout mouse model. We hope it will be helpful in better understanding how the trace element selenium participates in the reduction of L-Met-O and becomes involved in neurobiology.

scholarly journals Peptide-Bound Methionine Sulfoxide (MetO) Levels and MsrB2 Abundance Are Differentially Regulated during the Desiccation Phase in Contrasted Acer Seeds

Antioxidants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 391 ◽  
Author(s):  
Natalia Wojciechowska ◽  
Shirin Alipour ◽  
Ewelina Stolarska ◽  
Karolina Bilska ◽  
Pascal Rey ◽  
...  
Keyword(s):  
Desiccation Tolerance ◽  
Methionine Sulfoxide ◽  
Redox Status ◽  
Embryonic Axes ◽  
Seed Desiccation ◽  
Methionine Sulfoxide Reductases ◽  
Norway Maple ◽  
Orthodox Seeds ◽  
Oxidation Of Methionine ◽  
Reduced Forms

Norway maple and sycamore produce desiccation-tolerant (orthodox) and desiccation-sensitive (recalcitrant) seeds, respectively. Drying affects reduction and oxidation (redox) status in seeds. Oxidation of methionine to methionine sulfoxide (MetO) and reduction via methionine sulfoxide reductases (Msrs) have never been investigated in relation to seed desiccation tolerance. MetO levels and the abundance of Msrs were investigated in relation to levels of reactive oxygen species (ROS) such as hydrogen peroxide, superoxide anion radical and hydroxyl radical (•OH), and the levels of ascorbate and glutathione redox couples in gradually dried seeds. Peptide-bound MetO levels were positively correlated with ROS concentrations in the orthodox seeds. In particular, •OH affected MetO levels as well as the abundance of MsrB2 solely in the embryonic axes of Norway maple seeds. In this species, MsrB2 was present in oxidized and reduced forms, and the latter was favored by reduced glutathione and ascorbic acid. In contrast, sycamore seeds accumulated higher ROS levels. Additionally, MsrB2 was oxidized in sycamore throughout dehydration. In this context, the three elements •OH level, MetO content and MsrB2 abundance, linked together uniquely to Norway maple seeds, might be considered important players of the redox network associated with desiccation tolerance.

scholarly journals An unusual thioredoxin system in the facultative parasite Acanthamoeba castellanii

2021 ◽  
Vol 78 (7) ◽  
pp. 3673-3689
Author(s):  
David Leitsch ◽  
Alvie Loufouma Mbouaka ◽  
Martina Köhsler ◽  
Norbert Müller ◽  
Julia Walochnik
Keyword(s):  
Oxidative Stress ◽  
Stop Codon ◽  
Acanthamoeba Castellanii ◽  
Methionine Sulfoxide ◽  
Redox System ◽  
Methionine Sulfoxide Reductase ◽  
Methionine Sulfoxide Reductase A ◽  
Protein Levels ◽  
Thioredoxin System ◽  
Facultative Parasite

AbstractThe free-living amoeba Acanthamoeba castellanii occurs worldwide in soil and water and feeds on bacteria and other microorganisms. It is, however, also a facultative parasite and can cause serious infections in humans. The annotated genome of A. castellanii (strain Neff) suggests the presence of two different thioredoxin reductases (TrxR), of which one is of the small bacterial type and the other of the large vertebrate type. This combination is highly unusual. Similar to vertebrate TrxRases, the gene coding for the large TrxR in A. castellanii contains a UGA stop codon at the C-terminal active site, suggesting the presence of selenocysteine. We characterized the thioredoxin system in A. castellanii in conjunction with glutathione reductase (GR), to obtain a more complete understanding of the redox system in A. castellanii and the roles of its components in the response to oxidative stress. Both TrxRases localize to the cytoplasm, whereas GR localizes to the cytoplasm and the large organelle fraction. We could only identify one thioredoxin (Trx-1) to be indeed reduced by one of the TrxRases, i.e., by the small TrxR. This thioredoxin, in turn, could reduce one of the two peroxiredoxins tested and also methionine sulfoxide reductase A (MsrA). Upon exposure to hydrogen peroxide and diamide, only the small TrxR was upregulated in expression at the mRNA and protein levels, but not the large TrxR. Our results show that the small TrxR is involved in the A. castellanii’s response to oxidative stress. The role of the large TrxR, however, remains elusive.

scholarly journals Hypermetabolism of glutathione, glutamate and ornithine via redox imbalance in methylglyoxal-induced peritoneal injury rats

2019 ◽  
Author(s):  
Ichiro Hirahara ◽  
Eiji Kusano ◽  
Denan Jin ◽  
Shinji Takai
Keyword(s):  
Oxidative Stress ◽  
Intraperitoneal Administration ◽  
Methionine Sulfoxide ◽  
Mesenchymal Cell ◽  
Oxidative Stress Marker ◽  
Peritoneal Fibrosis ◽  
Metabolome Analysis ◽  
Glycation End Products ◽  
Excessive Proliferation

Abstract Peritoneal dialysis (PD) is a blood purification treatment for patients with reduced renal function. However, the peritoneum is exposed to oxidative stress during PD and long-term PD results in peritoneal damage, leading to the termination of PD. Methylglyoxal (MGO) contained in commercial PD fluids is a source of strong oxidative stress. The aim of this study was to clarify the mechanism of MGO-induced peritoneal injury using metabolome analysis in rats. We prepared peritoneal fibrosis rats by intraperitoneal administration of PD fluids containing MGO for 21 days. As a result, MGO-induced excessive proliferation of mesenchymal cells with an accumulation of advanced glycation end-products (AGEs) at the surface of the thickened peritoneum in rats. The effluent levels of methionine sulfoxide, an oxidative stress marker and glutathione peroxidase activity were increased in the MGO-treated rats. The levels of glutathione, glutamate, aspartate, ornithine and AGEs were also increased in these rats. MGO upregulated the gene expression of transporters and enzymes related to the metabolism of glutathione, glutamate and ornithine in the peritoneum. These results suggest that MGO may induce peritoneal injury with mesenchymal cell proliferation via increased redox metabolism, directly or through the formation of AGEs during PD.

scholarly journals The Role of Prophage for Genome Diversification within a Clonal Lineage of Lactobacillus johnsonii: Characterization of the Defective Prophage LJ771

2008 ◽  
Vol 190 (17) ◽  
pp. 5806-5813 ◽  
Author(s):  
Emmanuel Denou ◽  
Raymond David Pridmore ◽  
Marco Ventura ◽  
Anne-Cécile Pittet ◽  
Marie-Camille Zwahlen ◽  
...  
Keyword(s):  
Methionine Sulfoxide ◽  
Gene Cassette ◽  
Methionine Sulfoxide Reductase ◽  
Toxin Gene ◽  
Clonal Lineage ◽  
Lactobacillus Johnsonii ◽  
Reductase Gene ◽  
Phage Dna

ABSTRACT Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isolates belonged to the same clonal lineage and differed mainly by a 40.8-kb prophage, LJ771, belonging to the Sfi11 phage lineage. LJ771 shares close DNA sequence identity with Lactobacillus gasseri prophages. LJ771 coexists as an integrated prophage and excised circular phage DNA, but phage DNA packaged into extracellular phage particles was not detected. Between the phage lysin gene and attR a likely mazE (“antitoxin”)/pemK (“toxin”) gene cassette was detected in LJ771 but not in the L. gasseri prophages. Expressed pemK could be cloned in Escherichia coli only together with the mazE gene. LJ771 was shown to be highly stable and could be cured only by coexpression of mazE from a plasmid. The prophage was integrated into the methionine sulfoxide reductase gene (msrA) and complemented the 5′ end of this gene, creating a protein with a slightly altered N-terminal sequence. The two L. johnsonii strains had identical in vitro growth and in vivo gut persistence phenotypes. Also, in an isogenic background, the presence of the prophage resulted in no growth disadvantage.

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