- Enhancement of amino acid detection and quantification by electrospray ionization mass spectrometry
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A new strategy for amino acid analysis is reported involving derivatization with an N-hydroxysuccinimide ester of N-alkylnicotinic acid (C n-NA-NHS) followed by reversed-phase chromatography and electrospray ionization mass spectrometry (RPC-MS). Detection sensitivity increased as the N-alkyl chain length of the nicotinic acid derivatizing agent was increased from 1 to 4. N-Acylation of amino acids with the Cn-NA-NHS reagents in water produced a stable product in roughly 1 min using a 4-fold molar excess of derivatizing agent in 0.1 M sodium borate buffer at pH values ranging from 8.5 to 10. Some O-acylation of tyrosine was also observed, but the product hydrolyzed within a few minutes at pH 10. The cystine product also degraded slowly over the course of a few days from reduction of the disulfide bond to form cysteine. The retention time of Cn-NA derivatized amino acids was lengthened in reversed-phase chromatography to the extent that polar amino acids were retained beyond the solvent peak, particularly in the cases of the C3-NA and C4-NA derivatives. Complete resolution of 18 amino acids was achieved in 28 min using the C4-NA-NHS reagent. Compared to N-acylation with benzoic acid, derivatization with C 4-NA-NHS increased MS detection sensitivity 6-80-fold. This was attributed to the surfactant properties of the Cn-NA-NHS reagents. The quaternary amine increased the charge on amino acid conjugates while the presence of an adjacent alkyl chain further increased ionization efficiency by apparently enhancing amino acid migration to the surface of electrospray droplets. Further modification of the Cn-NA-NHS reagents with deuterium was used to prepare coded sets of derivatizing agents. These coding agents were used to differentially code samples and after mixing carry out comparative concentration measurements between samples using extracted ion chromatograms to estimate relative peak areas of derivatized amino acids.
- Yang, Wen-Chu,Mirzaei, Hamid,Liu, Xiuping,Regnier, Fred E.
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- Highly sensitive quantitative analysis of nicotianamine using LC/ESI-TOF-MS with an internal standard
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A highly sensitive quantitative method for analyzing nicotianamine (NA) by liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOF-MS) is reported. Fluorenylmethoxycarbonylation of nicotianamine reduced its polarity and enabled its retention in a reversed-phase column. The adoption of Nε-nicotyllysine (NL) as an internal standard ensured reliable quantification by giving a linear calibration curve drawn between the NA/NL molar ratios of standard solutions injected and the NA/NL area ratios in mass chromatograms. The high sensitivity of this analytical method allowed us to measure the amount of NA. This analytical method has applications to all research concerning NA.
- Wada, Yasuaki,Yamaguchi, Isomaro,Takahashi, Michiko,Nakanishi, Hiromi,Mori, Satoshi,Nishizawa, Naoko K.
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- Structure-activity relationships of N-terminal variants of peptidomimetic tissue transglutaminase inhibitors
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Tissue transglutaminase (TG2) is a multifunctional protein that catalyses protein crosslinking in the extracellular matrix, and functions as an intracellular G-protein. While both activities have been associated with human diseases, its role as a G-protein has been linked to cancer stem cell survival and maintenance of a metastatic phenotype. Recently we have shown that targeted covalent inhibitors (TCIs) can react selectively with the enzyme active site of TG2, to allosterically abolish its ability to bind GTP. In the present work, we focused on the variation of the N-terminal group of these peptidomimetic inhibitors, in order to enhance efficiency, while reducing log P and the number of rotatable bonds. This approach led to the synthesis and evaluation of 41 novel inhibitors, some of which had greatly improved efficiency and affinity for TG2 (e.g. TCI 72: KI = 1.0 μM, kinact/KI = 4.4 × 105 M?1 min?1). Molecular modelling provided a hypothetical binding mode for these TCIs. The most efficient inhibitors were evaluated further and shown to have excellent isozyme selectivity, to block GTP binding, and to have improved pharmacokinetic properties, as expected. Their biological activity was also confirmed, in a cellular invasion assay, although with less potency than expected.
- Adhikary, Gautam,Cundy, Nicholas J.,Eckert, Richard L.,Eisinga, Sarah,Firoozi, Neda,Gates, Eric W. J.,Keillor, Jeffrey W.,Leccese, Jessica,McNeil, Nicole M. R.,Tyndall, Joel D. A.
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- Halide-Accelerated Acyl Fluoride Formation Using Sulfuryl Fluoride
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Herein, we report a new one-pot sequential method for SO2F2-mediated nucleophilic acyl substitution reactions starting from carboxylic acids. A mechanistic study revealed that SO2F2-mediated acid activation proceeds via the anhydride, which is then converted to the corresponding acyl fluoride. Tetrabutylammonium chloride or bromide accelerate the formation of acyl fluoride. Optimized halide-accelerated conditions were used to synthesize acyl fluorides in 30-80percent yields, and esters, amides, and thioesters in 72-96percent yields without reoptimization for each nucleophile.
- Foth, Paul J.,Malig, Thomas C.,Yu, Hao,Bolduc, Trevor G.,Hein, Jason E.,Sammis, Glenn M.
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p. 6682 - 6686
(2020/09/02)
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- SIRT1 ACTIVATING COMPOUNDS
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Provided herein are methods and compositions for preventing or treating aging, or an aging-related disorder, a disorder associated with inflammation, or for modulating an immune response in a subject in need thereof. In some embodiments, the methods comprise administering to the subject an effective amount of a compound of Formulas I-XIII.
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Page/Page column 63; 65-66
(2020/05/21)
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- Synthesis and Biochemical Evaluation of Nicotinamide Derivatives as NADH Analogue Coenzymes in Ene Reductase
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Nicotinamide and pyridine-containing conjugates have attracted a lot of attention in research as they have found use in a wide range of applications including as redox flow batteries and calcium channel blockers, in biocatalysis, and in metabolism. The interesting redox character of the compounds’ pyridine/dihydropyridine system allows them to possess very similar characteristics to the natural chiral redox agents NAD+/NADH, even mimicking their functions. There has been considerable interest in designing and synthesizing NAD+/NADH mimetics with similar redox properties. In this research, three nicotinamide conjugates were designed, synthesized, and characterized. Molecular structures obtained through X-ray crystallography were obtained for two of the conjugates, thereby providing more detail on the bonding and structure of the compounds. The compounds were then further evaluated for biochemical properties, and it was found that one of the conjugates possessed similar functions and characteristics to the natural NADH. This compound was evaluated in the active enzyme, enoate reductase; like NADH, it was shown to help reduce the C=C double bond of three substrates and even outperformed the natural coenzyme. Kinetic data are reported.
- Falcone, Natashya,She, Zhe,Syed, Jebreil,Lough, Alan,Kraatz, Heinz-Bernhard
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p. 838 - 845
(2019/02/07)
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- Structure-Activity Relationships of Potent, Targeted Covalent Inhibitors That Abolish Both the Transamidation and GTP Binding Activities of Human Tissue Transglutaminase
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Human tissue transglutaminase (hTG2) is a multifunctional enzyme. It is primarily known for its calcium-dependent transamidation activity that leads to formation of an isopeptide bond between glutamine and lysine residues found on the surface of proteins, but it is also a GTP binding protein. Overexpression and unregulated hTG2 activity have been associated with numerous human diseases, including cancer stem cell survival and metastatic phenotype. Herein, we present a series of targeted covalent inhibitors (TCIs) based on our previously reported Cbz-Lys scaffold. From this structure-activity relationship (SAR) study, novel irreversible inhibitors were identified that block the transamidation activity of hTG2 and allosterically abolish its GTP binding ability with a high degree of selectivity and efficiency (kinact/KI > 105 M-1 min-1). One optimized inhibitor (VA4) was also shown to inhibit epidermal cancer stem cell invasion with an EC50 of 3.9 μM, representing a significant improvement over our previously reported "hit" NC9.
- Akbar, Abdullah,McNeil, Nicole M. R.,Albert, Marie R.,Ta, Viviane,Adhikary, Gautam,Bourgeois, Karine,Eckert, Richard L.,Keillor, Jeffrey W.
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p. 7910 - 7927
(2017/10/06)
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- Palladium-Catalyzed Carbonylation of (Hetero)Aryl, Alkenyl and Allyl Halides by Means of N-Hydroxysuccinimidyl Formate as CO Surrogate
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An efficient Pd-catalyzed carbonylation protocol is described for the coupling of a large panel of aryl, heteroaryl, benzyl, vinyl and allyl halides 2 with the unusual N-hydroxysuccinimidyl (NHS) formate 1 as a CO surrogate to afford the corresponding valuable NHS esters 3. High conversion to the coupling products was achieved with up to 98% yield by means of Pd(OAc)2/Xantphos catalyst system.
- Barré, Ana?s,T?nta?, Mihaela-Liliana,Alix, Florent,Gembus, Vincent,Papamica?l, Cyril,Levacher, Vincent
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p. 6537 - 6544
(2015/10/05)
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- General method for the preparation of active esters by palladium-catalyzed alkoxycarbonylation of aryl bromides
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A useful method was developed for the synthesis of active esters by palladium-catalyzed alkoxycarbonylation of (hetero)aromatic bromides. The protocol was general for a range of oxygen nucleophiles including N-hydroxysuccinimide (NHS), pentafluorophenol (PFP), hexafluoroisopropyl alcohol (HFP), 4-nitrophenol, and N-hydroxyphthalimide. A high functional group tolerance was displayed, and several active esters were prepared with good to excellent isolated yields. The protocol was extended to access an important synthetic precursor to the HIV-protease inhibitor, saquinavir, by formation of an NHS ester followed by acyl substitution.
- De Almeida, Angelina M.,Andersen, Thomas L.,Lindhardt, Anders T.,De Almeida, Mauro V.,Skrydstrup, Troels
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supporting information
p. 1920 - 1928
(2015/02/19)
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- Pyridylthiourea-grafted polyethylenimine offers an effective assistance to siRNA-mediated gene silencing in vitro and in vivo
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Success of synthetic interfering nucleic acids (siRNAs)-based therapy relies almost exclusively on effective, safe and preferably nanometric delivery systems which can be easily prepared, even at high concentrations. We prepared by chemical synthesis vari
- Creusat, Gaelle,Thomann, Jean-Sébastien,Maglott, Anne,Pons, Bénédicte,Dontenwill, Monique,Guérin, Eric,Frisch, Benoit,Zuber, Guy
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experimental part
p. 418 - 426
(2012/06/17)
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- Synthesis of Conjugates of hyaluronic and nicotinic acids
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Conjugates with nicotinic acid of hyaluronic acid carboxylic and hydroxyl groups were synthesized and exhibited polyampholyte properties.
- Ponedel'kina,Sal'nikova,Lukina,Tyumkina,Odinokov
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experimental part
p. 189 - 193
(2012/09/08)
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- A new protocol for selective cleavage of acyl protecting groups in 2′-O-modified 3′,5′-O -(Tetraisopropyldisiloxane-1,3-diyl) ribonucleosides
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The stability of tetraisopropyldisiloxane-1,3-diyl (TIPDS) protection in nucleosides in ammonia/amine solutions in methanol and ethanol was studied. In ammonia-methanol at ambient temperature significant partial cleavage of TIPDS was observed. When ethano
- Drenichev,Kulikova,Bobkov,Tararov,Mikhailov
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experimental part
p. 3827 - 3834
(2011/01/12)
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- Expansion of repertoire of modified DNAs prepared by PCR using KOD Dash DNA polymerase
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Thymidine analogues bearing a variety of functional groups at the C5-position via an amino-linker arm were prepared and the substrate activity for PCR using thermophilic KOD Dash DNA polymerase was examined. The enzyme accepted the thymidine analogues bea
- Ohbayashi, Tsutomu,Kuwahara, Masayasu,Hasegawa, Masatoshi,Kasamatsu, Toshiyuki,Tamura, Takehiro,Sawai, Hiroaki
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p. 2463 - 2468
(2007/10/03)
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- PROCESS FOR CONVERSION OF PHENOLS TO CARBOXAMIDES VIA THE SUCCINIMIDE ESTERS
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A process for converting an aryl triflate, heteroaryl triflate, aryl halide or heteroaryl halide to an N-hydroxysuccinimido este is disclosed. The process involves reacting the triflate or halide with carbon monoxide and N-hydroxysuccinimide in a solvent in the presence of a palladium catalyst and a base.
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- Preparation of N-hydroxysuccinimido esters via palladium-catalyzed carbonylation of aryl triflates and halides
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N-Hydroxysuccinimido esters of aromatic carboxylic acids (a.k.a. active esters) can be made using a potentially general, one-step procedure via Pd-catalyzed carbonylation of an aryl triflate or aryl iodide with CO and N-hydroxysuccinimide. Excellent yields (up to 94%) were observed when the reaction was done in DMSO at 70°C and 1 atmosphere of CO pressure.
- Lou, Rongliang,VanAlstine, Melissa,Sun, Xufeng,Wentland, Mark P.
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p. 2477 - 2480
(2007/10/03)
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- Preparation of deuterated methyl and dimethyl substituted nicotinoylating agents for derivatization of the N-terminal of protein.
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Methyl groups of 6-methylnicotinic acid and 2,6-dimethylnicotinic acid were deuterated by an H-D exchange reaction under conditions of 1% NaOD/D(2)O on heating. With a condensation reaction between the D-labeled nicotinic acid derivative and N-hydroxysuccinimide with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, the nicotinoylating agents, 1-(6-methyl[D(3)]nicotinoyloxy)succinimide (2c) and 1-(2,6-dimethyl[D(6)]nicotinoyloxy)succinimide (2f) were prepared. Both D-labeled nicotinoylating agents and their unlabeled counterparts quantitatively modified the N-terminal of protein.
- Tsumoto, Hiroki,Murata, Chie,Miyata, Naoki,Taguchi, Ryo,Kohda, Kohfuku
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p. 1399 - 1401
(2007/10/03)
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- Multifunctional dinucleotide analogs for the generation of complex RNA conjugates
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Oligonucleotide conjugates are needed for in vitro selection schemes aiming at reactions between small, organic reactants. A general strategy is provided for the generation of the required RNA reactant conjugates based on multifunctional dinucleotide anal
- Hausch, Felix,J?schke, Andres
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p. 1261 - 1268
(2007/10/03)
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- N-Acylphenylalanines and Related Compounds. A New Class of Oral Hypoglycemic Agents
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N-Benzoyl-DL-phenylalanine (1) was found to possess hypoglycemic activity.A series of the analogues of compound 1 were prepared and evaluated for their blood glucose lowering activity.Both the steric effects of the phenylalanine moiety and the effects of variations in the acyl moiety were investigated.This study elucidated some of the structure-activity relationships and led to the development of N-(4-ethylbenzoyl)-D-phenylalanine (34), which was 50 times more potent than the initial compound 1.
- Shinkai, Hisashi,Toi, Koji,Kumashiro, Izumi,Seto, Yoshiko,Fukuma, Mariko,et al.
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p. 2092 - 2097
(2007/10/02)
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- Evaluation of the brain-specific delivery of radioiodinated (iodophenyl)alkyl-substituted amines coupled to a dihydropyridine carrier
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To evaluate the potential usefulness of radioiodinated phenylamines attached to dihydropyridine carriers as a means of brain-specific delivery of radiopharmaceuticals, 1-methyl-3-[N-[β-(4-[125I]iodophenyl)ethyl]carbamoyl]-1,4-dihydropyridine ([125I]-9) and 1-methyl-3-[N-(4-[125I]iodophenyl)carbamoyl[-1,4-dihydropyridine ([125I]-13) have been prepared by dithionite reduction of the corresponding pyridinium precursors, [125I]-8 and [125I]-12, respectively. Formation of 8 involved coupling of (p-aminophenyl)ethylamine with N-succinimidyl (1-methyl-3-pyridinio)formate iodide (4) followed by transformation to the corresponding N-piperidinyl- or (diethylamino)- triazines that were converted to 8 by treatment with HI. Alternatively, 12 was prepared by initial conversion of (4-aminophenyl)mercuric acetate to 4-iodoaniline by treatment with I2 and then coupling with 4. The radioiodinated quaternary products, 8 and 12, showed low brain uptake and low brain to blood ratios, whereas the dihydropyridine analogues. 9 and 13, showed comparatively good brain uptake and good brain to blood ratios in rats. These data demonstrate that dihydropyridine-coupled radiopharmaceuticals can cross the blood-brain barrier and the technique may be useful for the measurement of cerebral blood perfusion.
- Tedjamulia,Srivastava,Knapp Jr.
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p. 1574 - 1580
(2007/10/02)
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- NAD(P)+-NAD(P)H. 39. Asymmetric Reduction by 1,4-Dihydronicotinamide Derivative Bound to Protein
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1,4-Dihydronicotinamide derivatives covalently bound to NH2 or SH group of proteins such as reduced keratin (RK), egg white albumin (EWA), and bovine serum albumin (BSA) have been synthesized and subjected to the reductions of α,α,α-trifluoroacetophenone
- Ohno, Atsuyoshi,Ushida, Satoshi,Oka, Shinzaburo
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p. 564 - 567
(2007/10/02)
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