The Experts below are selected from a list of 2475 Experts worldwide ranked by ideXlab platform
Shuji Kishi - One of the best experts on this subject based on the ideXlab platform.
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publisher correction double mimicry evades trna synthetase editing by toxic vegetable sourced non Proteinogenic Amino Acid
2018Co-Authors: Youngzee Song, Huihao Zhou, Yi Shi, Mir Hussain Nawaz, Oscar Vargasrodriguez, Jolene K Diedrich, John R Yates, Shuji KishiAbstract:In the original version of this Article, extraneous text not belonging to the article was accidentally appended to end of the first paragraph of the discussion. This error has now been corrected in both the PDF and HTML versions of the Article.
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double mimicry evades trna synthetase editing by toxic vegetable sourced non Proteinogenic Amino Acid
2017Co-Authors: Youngzee Song, Huihao Zhou, Yi Shi, Mir Hussain Nawaz, Oscar Vargasrodriguez, Jolene K Diedrich, John R Yates, Shuji KishiAbstract:Hundreds of non-Proteinogenic (np) Amino Acids (AA) are found in plants and can in principle enter human protein synthesis through foods. While Aminoacyl-tRNA synthetase (AARS) editing potentially provides a mechanism to reject np AAs, some have pathological associations. Co-crystal structures show that vegetable-sourced azetidine-2-carboxylic Acid (Aze), a dual mimic of proline and alanine, is activated by both human prolyl- and alanyl-tRNA synthetases. However, it inserts into proteins as proline, with toxic consequences in vivo. Thus, dual mimicry increases odds for mistranslation through evasion of one but not both tRNA synthetase editing systems.
Juan C Carretero - One of the best experts on this subject based on the ideXlab platform.
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catalytic asymmetric direct mannich reaction a powerful tool for the synthesis of α β diAmino Acids
2009Co-Authors: Ramon Gomez Arrayas, Juan C CarreteroAbstract:Optically active α,β-diAmino Acids are very attractive targets in organic synthesis because of their wide-ranging biological significance and high versatility as synthetic building blocks. Efficient synthesis of such non-Proteinogenic Amino Acid derivatives must face the challenge of generating two contiguous stereocenters with complete diastereo- and enantiocontrol in flexible, acyclic molecules. The catalytic asymmetric direct Mannich reaction has provided elegant and efficient solutions for the stereocontrolled assembly of both syn- and anti-α,β-diAmino Acid derivatives, including those with a α-tetrasubstituted carbon stereocenter, with the aid of either organometallic or purely organic chiral catalysts (or the combination of both). This tutorial review highlights progress in this area, which has recently been boosted through two complementary strategies: the direct Mannich reaction of glycine ester Schiff bases with imines and the direct aza-Henry reaction between nitro compounds and imines.
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catalytic asymmetric direct mannich reaction a powerful tool for the synthesis of alpha beta diAmino Acids
2009Co-Authors: Ramon Gomez Arrayas, Juan C CarreteroAbstract:Optically active α,β-diAmino Acids are very attractive targets in organic synthesis because of their wide-ranging biological significance and high versatility as synthetic building blocks. Efficient synthesis of such non-Proteinogenic Amino Acid derivatives must face the challenge of generating two contiguous stereocenters with complete diastereo- and enantiocontrol in flexible, acyclic molecules. The catalytic asymmetric direct Mannich reaction has provided elegant and efficient solutions for the stereocontrolled assembly of both syn- and anti-α,β-diAmino Acid derivatives, including those with a α-tetrasubstituted carbon stereocenter, with the aid of either organometallic or purely organic chiral catalysts (or the combination of both). This tutorial review highlights progress in this area, which has recently been boosted through two complementary strategies: the direct Mannich reaction of glycine ester Schiff bases with imines and the direct aza-Henry reaction between nitro compounds and imines.
T G Downing - One of the best experts on this subject based on the ideXlab platform.
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the metabolism of the non Proteinogenic Amino Acid β n methylAmino l alanine bmaa in the cyanobacterium synechocystis pcc6803
2016Co-Authors: Simone Downing, T G DowningAbstract:The neurotoxic Amino Acid β-N-methylAmino-L-alanine (BMAA) is produced by cyanobacteria under nitrogen starvation conditions and its metabolism is closely associated with cellular nitrogen control. Very little is known regarding the metabolism or biosynthesis of this Amino Acid in the producing organisms and current knowledge is limited to the spontaneous formation of carbamate adducts in the presence of aqueous carbon dioxide, the rapid removal of free cellular BMAA upon the addition of ammonia to nitrogen-starved cyanobacterial cultures, and the link between cellular nitrogen status and BMAA synthesis. Data presented here show that exogenous BMAA is readily metabolised by cyanobacteria during which, the primary Amino group is rapidly transferred to other cellular Amino Acids. Furthermore, data suggest that BMAA is metabolised in cyanobacteria via a reversible transamination reaction. This study presents novel data on BMAA metabolism in cyanobacteria and provides the first proposed biosynthetic precursor to BMAA biosynthesis in cyanobacteria.
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β n methylAmino l alanine bmaa uptake by the aquatic macrophyte ceratophyllum demersum
2011Co-Authors: M Esterhuizen, Stephan Pflugmacher, T G DowningAbstract:Free-living freshwater cyanobacteria contain BMAA in both free cellular and protein-associated forms. Free BMAA released on bloom collapse or during cellular turnover creates a potential source of the non-Proteinogenic Amino Acid for bioaccumulation and biomagnification in aquatic ecosystems. Uptake of free Amino Acids is well documented in macrophytes and the potential for aquatic macrophytes to bioaccumulate BMAA therefore poses a potential threat where such macrophytes constitute a food source in an ecosystem. BMAA uptake and accumulation by the aquatic macrophyte Ceratophyllum demersum was therefore investigated. Rapid uptake of significant amounts of BMAA was observed in C. demersum. Both free and protein-associated BMAA were observed with protein association following accumulation of free BMAA. The protein association suggests potential biomaccumulation by aquatic macrophytes and offers a possibility of phytoremediation for BMAA removal.
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β n methylAmino l alanine bmaa in novel south african cyanobacterial isolates
2008Co-Authors: M Esterhuizen, T G DowningAbstract:Abstract β - N -methylAmino- l -alanine (BMAA) is a neurotoxic non-Proteinogenic Amino Acid reportedly produced by the majority of cyanobacterial isolates. A novel method was developed for the detection of BMAA in biological samples. Cultures representing the taxonomic diversity and geographic distribution in Southern Africa were collected and made uni-algal by standard methods before analysis for the presence of both free and protein-associated BMAA. Protein-associated BMAA was released by Acid hydrolysis in an inert atmosphere. Samples were analyzed by gas chromatography–mass spectrometry (GC–MS) with pre-derivatization of Amino Acids using Phenomonex EZ:faast™ of the tested cultures, 96% were positive for BMAA although several were below the limit for quantification. BMAA presence was not related to the geographic origin or taxonomy of isolates and no correlation between free and bound BMAA concentrations was observed within or between taxonomic groups. These data offer the first confirmation of the taxonomic and geographic ubiquity of BMAA in freshwater cyanobacteria.
Huihao Zhou - One of the best experts on this subject based on the ideXlab platform.
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publisher correction double mimicry evades trna synthetase editing by toxic vegetable sourced non Proteinogenic Amino Acid
2018Co-Authors: Youngzee Song, Huihao Zhou, Yi Shi, Mir Hussain Nawaz, Oscar Vargasrodriguez, Jolene K Diedrich, John R Yates, Shuji KishiAbstract:In the original version of this Article, extraneous text not belonging to the article was accidentally appended to end of the first paragraph of the discussion. This error has now been corrected in both the PDF and HTML versions of the Article.
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double mimicry evades trna synthetase editing by toxic vegetable sourced non Proteinogenic Amino Acid
2017Co-Authors: Youngzee Song, Huihao Zhou, Yi Shi, Mir Hussain Nawaz, Oscar Vargasrodriguez, Jolene K Diedrich, John R Yates, Shuji KishiAbstract:Hundreds of non-Proteinogenic (np) Amino Acids (AA) are found in plants and can in principle enter human protein synthesis through foods. While Aminoacyl-tRNA synthetase (AARS) editing potentially provides a mechanism to reject np AAs, some have pathological associations. Co-crystal structures show that vegetable-sourced azetidine-2-carboxylic Acid (Aze), a dual mimic of proline and alanine, is activated by both human prolyl- and alanyl-tRNA synthetases. However, it inserts into proteins as proline, with toxic consequences in vivo. Thus, dual mimicry increases odds for mistranslation through evasion of one but not both tRNA synthetase editing systems.
Mir Hussain Nawaz - One of the best experts on this subject based on the ideXlab platform.
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publisher correction double mimicry evades trna synthetase editing by toxic vegetable sourced non Proteinogenic Amino Acid
2018Co-Authors: Youngzee Song, Huihao Zhou, Yi Shi, Mir Hussain Nawaz, Oscar Vargasrodriguez, Jolene K Diedrich, John R Yates, Shuji KishiAbstract:In the original version of this Article, extraneous text not belonging to the article was accidentally appended to end of the first paragraph of the discussion. This error has now been corrected in both the PDF and HTML versions of the Article.
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double mimicry evades trna synthetase editing by toxic vegetable sourced non Proteinogenic Amino Acid
2017Co-Authors: Youngzee Song, Huihao Zhou, Yi Shi, Mir Hussain Nawaz, Oscar Vargasrodriguez, Jolene K Diedrich, John R Yates, Shuji KishiAbstract:Hundreds of non-Proteinogenic (np) Amino Acids (AA) are found in plants and can in principle enter human protein synthesis through foods. While Aminoacyl-tRNA synthetase (AARS) editing potentially provides a mechanism to reject np AAs, some have pathological associations. Co-crystal structures show that vegetable-sourced azetidine-2-carboxylic Acid (Aze), a dual mimic of proline and alanine, is activated by both human prolyl- and alanyl-tRNA synthetases. However, it inserts into proteins as proline, with toxic consequences in vivo. Thus, dual mimicry increases odds for mistranslation through evasion of one but not both tRNA synthetase editing systems.
