- Ruckerbactin Produced by Yersinia ruckeri YRB Is a Diastereomer of the Siderophore Trivanchrobactin Produced by Vibrio campbellii DS40M4
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The Gram-negative bacterium Yersinia ruckeri is the causative agent for enteric red mouth disease in salmonids. The genome of Y. ruckeri YRB contains a biosynthetic gene cluster encoding the biosynthesis of catechol siderophores that are diastereomeric with the known vanchrobactin class of siderophores, (DHBDArgLSer)(1–3). Ruckerbactin (1), produced by Y. ruckeri YRB, was found to be the linear tris-l-serine ester composed of l-arginine and 2,3-dihydroxybenzoic acid, (DHBLArgLSer)3. The biscatechol, (DHBLArgLSer)2 (2), and monocatechol, DHBLArgLSer (3), compounds were also isolated and characterized. The macrolactone of ruckerbactin was not detected. The presence of LArg in ruckerbactin makes it the diastereomer of trivanchrobactin with DArg. The electronic circular dichroism spectra of Fe(III)–ruckerbactin and Fe(III)–trivanchrobactin reveal the opposite enantiomeric configurations at the Fe(III) sites. Fe(III)–ruckerbactin adopts the Δ configuration, and Fe(III)–trivanchrobactin adopts the Λ configuration. Y. ruckeri YRB was also found to produce the antimicrobial agent holomycin (4).
- Butler, Alison,Dulaney, Kalana,Reitz, Zachary L.,Stow, Parker R.,Thomsen, Emil
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p. 264 - 269
(2022/01/15)
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- LAT-1 activity of meta-substituted phenylalanine and tyrosine analogs
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The transporter protein Large-neutral Amino Acid Transporter 1 (LAT-1, SLC7A5) is responsible for transporting amino acids such as tyrosine and phenylalanine as well as thyroid hormones, and it has been exploited as a drug delivery mechanism. Recently its role in cancer has become increasingly appreciated, as it has been found to be up-regulated in many different tumor types, and its expression levels have been correlated with prognosis. Substitution at the meta position of aromatic amino acids has been reported to increase affinity for LAT-1; however, the SAR for this position has not previously been explored. Guided by newly refined computational models of the binding site, we hypothesized that groups capable of filling a hydrophobic pocket would increase binding to LAT-1, resulting in improved substrates relative to parent amino acid. Tyrosine and phenylalanine analogs substituted at the meta position with halogens, alkyl and aryl groups were synthesized and tested in cis-inhibition and trans-stimulation cell assays to determine activity. Contrary to our initial hypothesis we found that lipophilicity was correlated with diminished substrate activity and increased inhibition of the transporter. The synthesis and SAR of meta-substituted phenylalanine and tyrosine analogs is described.
- Augustyn, Evan,Finke, Karissa,Zur, Arik A.,Hansen, Logan,Heeren, Nathan,Chien, Huan-Chieh,Lin, Lawrence,Giacomini, Kathleen M.,Colas, Claire,Schlessinger, Avner,Thomas, Allen A.
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supporting information
p. 2616 - 2621
(2016/05/09)
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- LAT1 activity of carboxylic acid bioisosteres: Evaluation of hydroxamic acids as substrates
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Large neutral amino acid transporter 1 (LAT1) is a solute carrier protein located primarily in the blood–brain barrier (BBB) that offers the potential to deliver drugs to the brain. It is also up-regulated in cancer cells, as part of a tumor's increased metabolic demands. Previously, amino acid prodrugs have been shown to be transported by LAT1. Carboxylic acid bioisosteres may afford prodrugs with an altered physicochemical and pharmacokinetic profile than those derived from natural amino acids, allowing for higher brain or tumor levels of drug and/or lower toxicity. The effect of replacing phenylalanine's carboxylic acid with a tetrazole, acylsulfonamide and hydroxamic acid (HA) bioisostere was examined. Compounds were tested for their ability to be LAT1 substrates using both cis-inhibition and trans-stimulation cell assays. As HA-Phe demonstrated weak substrate activity, its structure–activity relationship (SAR) was further explored by synthesis and testing of HA derivatives of other LAT1 amino acid substrates (i.e., Tyr, Leu, Ile, and Met). The potential for a false positive in the trans-stimulation assay caused by parent amino acid was evaluated by conducting compound stability experiments for both HA-Leu and the corresponding methyl ester derivative. We concluded that HA's are transported by LAT1. In addition, our results lend support to a recent account that amino acid esters are LAT1 substrates, and that hydrogen bonding may be as important as charge for interaction with the transporter binding site.
- Zur, Arik A.,Chien, Huan-Chieh,Augustyn, Evan,Flint, Andrew,Heeren, Nathan,Finke, Karissa,Hernandez, Christopher,Hansen, Logan,Miller, Sydney,Lin, Lawrence,Giacomini, Kathleen M.,Colas, Claire,Schlessinger, Avner,Thomas, Allen A.
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supporting information
p. 5000 - 5006
(2016/10/05)
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- Micropeptins from an Israeli fishpond water bloom of the cyanobacterium microcystis sp
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Seven new natural products, micropeptin MZ845 (1), micropeptin MZ859 (2), micropeptin MZ939A (3), micropeptin MZ925 (4), micropeptin MZ939B (5), micropeptin MZ1019 (6), and micropeptin MZ771 (7), as well as two known micropeptins, cyanopeptolin S (8) and cyanopeptolin SS (9), were isolated from the hydrophilic extract of the cyanobacterium Microcystis sp. that was collected from a fishpond in Kibbutz Ma'ayan Tzvi, Israel, in July 2006. The structures of the pure natural products were elucidated using spectroscopic methods, including UV, 1D and 2D NMR, and MS techniques. The absolute configuration of the chiral centers of the compounds was determined using Marfey's method for HPLC. The inhibitory activity of the compounds was determined for the serine proteases: trypsin, chymotrypsin, thrombin, and elastase. These micropeptins inhibited trypsin with IC50's that varied between 0.6 and 24.2 μM. The SAR of these micropeptins is discussed.
- Zafrir, Ella,Carmeli, Shmuel
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experimental part
p. 352 - 358
(2010/08/05)
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- Polyunsaturated fatty acid derivatives, pharmaceutical compositions containing the same, method for the preparation thereof, and their use as medicament
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The compounds of the Formula (I) STR1 wherein R1 is a C18-24 alkenyl containing at least two double bonds, or --(CH2)n --CH(NH2)m --COOH X is 0, NH or C1-4 alkyl-N, Y is CONH2, COOH or COOMe, wherein Me is hydrogen metal, and R2 is a side chain of a any amino acid except L-GLU or L-ASP at α-position or a group of Formula wherein k is zero or an integer of 1, n is zero or an integer of 1 to 3, m is zero or an integer of 1 to 4, A is hydroxyl or one A is hydroxyl and the other A is hydrogen. M is H or R1 --CO and X and R1 are as defined above and their salts having tyrosine kinase inhibitor activity can be used as antitumor agents.
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- Method of the production of immunoglobulin having high content of monomer
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A method of the production of immunoglobulin having a high content of monr from immunoglobulin-containing materials by a fractionation method, which comprises carrying out the fractionation in the presence of a water-soluble, basic nitrogen-containing organic compound having a dissociation constant (pKb) of 7 or less or an acid addition salt thereof, and thereby inhibiting by-production of undesirable aggregated molecules. The immunoglobulin has a high content of monomer and contains no or little aggregated molecules and hence can be used as a medicine in immune prophylaxis and immunotherapy without undesirable side effects and can be administered by intraveneous route, and further, is useful for the preparation of chemically treated immunoglobulin having a high content of monomer.
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