- Resolving the enigma of prebiotic C-O-P bond formation: Prebiotic hydrothermal synthesis of important biological phosphate esters
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Important biological phosphate esters such as sn-glycerol-3-phosphate, glycerol-2- phosphate, and phosphoethanolamine were synthesized under hydrothermal conditions. Phosphorus was incorporated into the biomolecules, leading to the formation of C-O-P type compounds hydrother- mally. Only perlite-catalyzed reaction at 180° C could result in the formation of sn-glycerol-3-phosphate, whereas glycerol-2-phosphate could be easily synthesized at 100°C with or without minerals and phos- phoethanolamine was obtained within a temperature range of 100 to 120°.
- Maheen, Gull,Tian, Ge,Wang, Yingwu,He, Chao,Shi, Zhan,Yuan, Hongming,Feng, Shouhua
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- Creation of a S1P Lyase bacterial surrogate for structure-based drug design
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S1P Lyase (SPL) has been described as a drug target in the treatment of autoimmune diseases. It plays an important role in maintaining intracellular levels of S1P thereby affecting T cell egress from lymphoid tissues. Several groups have already published approaches to inhibit S1P Lyase with small molecules, which in turn increase endogenous S1P concentrations resulting in immunosuppression. The use of structural biology has previously aided SPL inhibitor design. Novel construct design is at times necessary to provide a reagent for protein crystallography. Here we present a chimeric bacterial protein scaffold used for protein X-ray structures in the presence of early small molecule inhibitors. Mutations were introduced to the bacterial SPL from Symbiobacterium thermophilum which mimic the human enzyme. As a result, two mutant StSPL crystal structures resolved to 2.8 ? and 2.2 ? resolutions were solved and provide initial structural hypotheses for an isoxazole chemical series, whose optimization is discussed in the accompanying paper.
- Argiriadi, Maria A.,Banach, David,Radziejewska, Elzbieta,Marchie, Susan,Dimauro, Jennifer,Dinges, Jurgen,Dominguez, Eric,Hutchins, Charles,Judge, Russell A.,Queeney, Kara,Wallace, Grier,Harris, Christopher M.
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- The sphingolipid degradation product trans-2-hexadecenal forms adducts with DNA
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Sphingosine 1-phosphate, a bioactive signaling molecule with diverse cellular functions, is irreversibly degraded by the endoplasmic reticulum enzyme sphingosine 1-phosphate lyase, generating trans-2-hexadecenal and phosphoethanolamine. We recently demonstrated that trans-2-hexadecenal causes cytoskeletal reorganization, detachment, and apoptosis in multiple cell types via a JNK-dependent pathway. These findings and the known chemistry of related α,β-unsaturated aldehydes raise the possibility that trans-2-hexadecenal may interact with additional cellular components. In this study, we show that it reacts readily with deoxyguanosine and DNA to produce the diastereomeric cyclic 1,. N2-deoxyguanosine adducts 3-(2-deoxy-β-d-erythro-pentofuranosyl)-5,6,7,8-tetrahydro-8. R-hydroxy-6. R-tridecylpyrimido[1,2-a]purine-10(3. H)one and 3-(2-deoxy-β-d-erythro-pentofuranosyl)-5,6,7,8-tetrahydro-8. S-hydroxy-6. S-tridecylpyrimido[1,2-a]purine-10(3. H)one. Thus, our findings suggest that trans-2-hexadecenal produced endogenously by sphingosine 1-phosphate lyase can react directly with DNA forming aldehyde-derived DNA adducts with potentially mutagenic consequences.
- Upadhyaya, Pramod,Kumar, Ashok,Byun, Hoe-Sup,Bittman, Robert,Saba, Julie D.,Hecht, Stephen S.
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scheme or table
p. 18 - 21
(2012/09/22)
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- Understanding non-enzymatic aminophospholipid glycation and its inhibition. Polar head features affect the kinetics of Schiff base formation
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Non-enzymatic aminophospholipid glycation is an especially important process because it alters the stability of lipid bilayers and interferes with cell function and integrity as a result. However, the kinetic mechanism behind this process has scarcely been studied. As in protein glycation, the process has been suggested to involve the formation of a Schiff base as the initial, rate-determining step. In this work, we conducted a comparative kinetic study of Schiff base formation under physiological conditions in three low-molecular weight analogues of polar heads in the naturally occurring aminophospholipids O-phosphorylethanolamine (PEA), O-phospho-dl-serine (PSer) and 2-aminoethylphenethylphosphate (APP) with various glycating carbonyl compounds (glucose, arabinose and acetol) and the lipid glycation inhibitor pyridoxal 5′-phosphate (PLP). Based on the results, the presence of a phosphate group and a carboxyl group in α position respect to the amino group decrease the formation constant for the Schiff base relative to amino acids. On the other hand, esterifying the phosphate group with a non-polar substituent in APP increases the stability of its Schiff base. The observed kinetic formation constants of aminophosphates with carbonyl groups were smaller than those for PLP. Our results constitute an important contribution to understanding the competitive inhibition effect of PLP on aminophospholipid glycation.
- Caldes, Catalina,Vilanova, Bartolome,Adrover, Miquel,Munoz, Francisco,Donoso, Josefa
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experimental part
p. 4536 - 4543
(2011/09/19)
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- Polyethylenimine-polyethyleneglycol-bis(aminoethylphosphate) nanoparticles mediated efficient DNA and siRNA transfection in mammalian cells
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In an attempt to circumvent toxic effects of branched polyethylenimine (bPEI, 25 kDa), it was crosslinked with varying proportions of a novel linker, PEG600-bis(aminoethylphosphate) (PaP), which resulted in the formation of nanoparticles (PPaP) in the range of 61-99 nm. These nanoparticles were found to have significantly lower toxicity in vitro than the native PEI. GFP expression in cells mediated by PPaP (8.1%)/DNA complex was found to be ~1.1-4.8 folds higher compared to GenePORTER 2, Lipofectamine, Superfect and native PEI in HeLa, HEK293 and CHO cells. FACS analysis on HeLa cells revealed ~62% transfected cells, whereas, in the case of the GenePORTER 2 transfection reagent, transfected cells were found to be ~36%. Intracellular trafficking in HeLa cells showed a significant population of PPaP (8.1%) nanoparticles and their DNA complex in nucleus after 1 h of treatment. Also, efficient delivery of GFP specific siRNA resulted in ~71% suppression of the target gene. DNase protection assay revealed that ~78% of complexed DNA was protected by PPaP(8.1%) nanoparticles even after 2 h of treatment. In vivo transgene expression studies in Balb/c mice showed significantly higher expression in the spleen. The results advocate the potential of PPaP nanoparticles as efficient carriers of nucleic acids in vivo. The Royal Society of Chemistry 2011.
- Patnaik, Soma,Tripathi, Sushil Kumar,Goyal, Ritu,Arora,Mitra, Kalyan,Villaverde,Vazquez,Shukla,Kumar,Gupta
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experimental part
p. 6103 - 6112
(2012/05/20)
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- The Stereochemical Course of Decarboxylation, Transamination and Elimination Reactions Catalysed by Escherichia coli Glutamic Acid Decarboxylase
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Pyridoxal 5'-phosphate dependent Escherichia coli glutamic acid decarboxylase reprotonates the quinonoid intermediate derived from the coenzyme and its natural substrate, (2S)-glutamic acid on the 4'-Si-face of the coenzyme during an abortive decarboxylation-transamination reaction.The enzyme introduces the 3-pro-R hydrogen of β-alanine with retention of configuration during the decarboxylation of (2S)-aspartic acid.In the absence of pyridoxal 5'-phosphate, treatment of the inactive apoenzyme with the inhibitor N4'-(2"-phosphoethyl)pyridoxamine 5'-phosphate results in reactivation through the formation of the active pyridoxal 5'-phosphate holoenzyme complex.During this reaction hydrogen phosphate is eliminated from the phosphoethyl moiety.Using synthetic chirally deuteriated isotopomers of the inhibitor it is demonstrated that the 1-pro-R hydrogen of inhibitor is removed during the reactivation reaction.The results suggest that protonations and deprotonations at Cα of quinonoid intermediates derived from the coenzyme and the substrate occur from the 4'-Si-face of the coenzyme and that the distal binding groups of the substrates and inhibitors occupy similar positions at the active site on the 3'-phenolic group side of the coenzyme.
- Tilley, Kevin,Akhtar, Mahmoud,Gani, David
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p. 3079 - 3088
(2007/10/02)
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