- THERMAL ISOMERIZATION OF N-OXALYL DERIVATIVES OF DIAMINO ACIDS
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The neurotoxic constituent of the legmure Lathyrus sativus, β-N-oxalyl-α,β-diaminopropionic acid, was thermally isomerized to an equilibrium mixture (60/40) containing the non-toxic α-N-oxalyl-α,β-diaminopropionic acid.The same equilibrium mixture was established by starting with the α isomer but required longer time. α- and γ-N-Oxalyl-α,γ-diaminobutyric acids also underwent thermally induced isomerization with α-γ, or γ-α migration of the oxalylgroup. δ-N-oxalylornithine and ε-N-oxalyllysine did not isomerize under these conditions.The observation that the higher homologes do not undergo isomerization suggest the intramolecular nature of the reaction. Key Word Index: Lathyrus sativus; α- and β-N-oxalyl-α,β-diaminopropionic acid; α-, γ-N-oxalyl-α,γ-diaminobutyric acids; δ-N-oxalylornithine; ε-N-oxalyllysine; neurotoxins; thermal isomerization.
- Abegaz, Berhanu M.,Nunn, Peter B.,Bruyn, Andre De,Lambein, Fernand
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- Synthesis of L-2,3-diaminopropionic acid, a siderophore and antibiotic precursor
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L-2,3-diaminopropionic acid (L-Dap) is an amino acid that is a precursor of antibiotics and staphyloferrin B a siderophore produced by Staphylococcus aureus. SbnA and SbnB are encoded by the staphyloferrin B biosynthetic gene cluster and are implicated in L-Dap biosynthesis. We demonstrate here that SbnA uses PLP and substrates O-phospho-L-serine and L-glutamate to produce a metabolite N-(1-amino-1-carboxyl-2-ethyl)-glutamic acid (ACEGA). SbnB is shown to use NAD+ to oxidatively hydrolyze ACEGA to yield α-ketoglutarate and L-Dap. Also, we describe crystal structures of SbnB in complex with NADH and ACEGA as well as with NAD+ and α-ketoglutarate to reveal the residues required for substrate binding, oxidation, and hydrolysis. SbnA and SbnB contribute to the iron sparing response of S. aureus that enables staphyloferrin B biosynthesis in the absence of an active tricarboxylic acid cycle.
- Kobylarz, Marek J.,Grigg, Jason C.,Takayama, Shin-Ichi J.,Rai, Dushyant K.,Heinrichs, David E.,Murphy, Michael E.P.
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- Structures and Biosynthetic Pathway of Coprisamides C and D, 2-Alkenylcinnamic Acid-Containing Peptides from the Gut Bacterium of the Carrion Beetle Silpha perforata
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Coprisamides C and D (1 and 2) were isolated from a gut bacterium, Micromonospora sp. UTJ3, of the carrion beetle Silpha perforata. Based on the combined analysis of UV, MS, and NMR spectral data, the planar structures of 1 and 2 were elucidated to be unreported derivatives of coprisamides A and B, cyclic depsipeptides bearing a 2-alkenylcinnamic acid unit and the unusual amino acids β-methylaspartic acid and 2,3-diaminopropanoic acid. The absolute configuration of 1 was determined using the advanced Marfey's method, phenylglycine methyl ester derivatization, and J-based configuration analysis. The biosynthetic gene clusters for the coprisamides were investigated based on genomic data from coprisamide-producing strains Micromonospora sp. UTJ3 and Streptomyces sp. SNU533. Coprisamide C (1) was active against the Mycobacterium tuberculosis mc26230 strain.
- Shin, Yern-Hyerk,Ban, Yeon Hee,Kim, Tae Ho,Bae, Eun Seo,Shin, Jongheon,Lee, Sang Kook,Jang, Jichan,Yoon, Yeo Joon,Oh, Dong-Chan
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- Unique polyhalogenated peptides from the marine sponge Ircinia sp.
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Two new bromopyrrole peptides, haloirciniamide A (1) and seribunamide A (2), have been isolated from an Indonesian marine sponge of the genus Ircinia collected in the Thousand Islands (Indonesia). The planar structure of both compounds was assigned on the basis of extensive 1D and 2D NMR spectroscopy and mass spectrometry. The absolute configuration of the amino acid residues in 1 and 2 was determined by the application of Marfey's method. Compound 1 is the first dibromopyrrole cyclopeptide having a chlorohistidine ring, while compound 2 is a rare peptide possessing a tribromopyrrole ring. Both compounds failed to show significant cytotoxicity against four human tumor cell lines, and neither compound was able to inhibit the enzyme topoisomerase I or impair the interaction between programmed cell death protein PD1 and its ligand, PDL1.
- Fernández, Rogelio,Bayu, Asep,Hadi, Tri Aryono,Bueno, Santiago,Pérez, Marta,Cuevas, Carmen,Putra, Masteria Yunovilsa
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- Catalyst functional group cooperativity in the amino acid-catalysed nitroaldol condensation reaction
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Several amino acids and their derivatives have been evaluated as organic catalysts for the nitroaldol reaction. It was found that when an unprotected amino group and an unprotected carboxylate group were present in the organocatalyst, both the nitroaldol reaction and subsequent elimination could occur to afford nitroalkenes from aromatic aldehydes and nitromethane. The best results were obtained by use of γ-amino acids derived from l-glutamine. It is suggested that the amino group is important for intermediate Schiff base formation and that the free carboxylate group facilitates the elimination step.
- Karadeniz, Leman,Astley, Stephen T.
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p. 3407 - 3415
(2013/09/23)
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- Total synthesis of nominal (11S)- and (11R)-cyclocinamide A
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The cyclocinamides possess a unique β2αβ 2α 14-membered tetrapeptide core. The initially reported biological data and intriguing structure, which was without full stereochemical identification, necessitated synthesis of both nominal (all-S) cyclocinamide A and the 11R isomer. The completed synthesis is highlighted by the use of a (cyclo)asparagine-containing dipeptide as a turn inducing fragment. Due to inconsistencies in analytical data between natural and synthetic samples, a re-evaluation of the natural product stereochemistry appears necessary.
- Garcia, Jessica M.,Curzon, Stephanie S.,Watts, Katharine R.,Konopelski, Joseph P.
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supporting information; experimental part
p. 2054 - 2057
(2012/06/29)
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- Calyxamides A and B, cytotoxic cyclic peptides from the marine sponge Discodermia calyx
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Cyclic peptides containing 5-hydroxytryptophan and thiazole moieties were isolated from the marine sponge Discodermia calyx collected near Shikine-jima Island, Japan. The structures of calyxamides A (1) and B (2), including the absolute configurations of all amino acids, were elucidated by spectroscopic analyses and degradation experiments. The structures are similar to keramamides F and G, previously isolated from Theonella sp. The analysis of the 16S rDNA sequences obtained from the metagenomic DNA of D. calyx revealed the presence of Candidatus Entotheonella sp., an unculturable δ-proteobacterium inhabiting the Theonella genus and implicated in the biosynthesis of bioactive peptides.
- Kimura, Miki,Wakimoto, Toshiyuki,Egami, Yoko,Tan, Karen Co,Ise, Yuji,Abe, Ikuro
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experimental part
p. 290 - 294
(2012/05/05)
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- Synthesis of cyclic guanidine intermediates of anatoxin-a(s) in both racemic and enantiomerically pure forms
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The alkyl chain of anatoxin-a(s) (cyclic guanidines), which can be used as an intermediate in the total synthesis of anatoxin-a(s), was synthesized in both racemic and enantiomerically pure forms. These enantiomerically pure cyclic compounds can be used as chiral inductors in some reactions. The two racemic routes disclosed herein have the advantages of high overall yield and mild reaction conditions. Both routes proceed through an intermediate 2,3-diaminoacid - an important synthetic scaffold - with good yields. Furthermore, the N,N-dimethyl-2(tosylimino)imidazolidine-4-carboxamide might be obtained from 2-(tosylimino)imidazolidine-4-carboxylic acid followed by selective reduction of the carbonyl functionality. All synthesized compounds were analyzed by mass spectrometry and 1H NMR and 1C NMR spectroscopy. Georg Thieme Verlag Stuttgart - New York.
- Moura, Sidnei,Pinto, Ernani
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scheme or table
p. 967 - 969
(2010/07/06)
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- Total synthesis of cyclotheonamide B, a facile route towards analogues
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A flexible, convergent synthesis of cyclotheonamide B (1b) was developed, starting from the constituent amino acids, using conventional benzyl-, t-butyl- and allyl-based protecting groups. By modification of the key intermediates, this approach allows the preparation of cyclotheonamide analogues.
- Bastiaans, Harold M. M.,Van Der Baan, Juul L.,Ottenheijm, Harry C. J.
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p. 5963 - 5966
(2007/10/02)
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- A convenient method for the cleavage of the D-mannosyl-L-gulose disaccharide from bleomycin-A2.
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In order to elucidate the biological role of the sugar residue of the antitumor drug bleomycin, this was deglycosylated by beta-elimination under mild alkaline conditions, and by solvolysis with hydrogen fluoride. The latter procedure proved to be better because it led to the complete deglycosylation without modification of the peptide, thus allowing further biological investigations of this component.
- Kenani,Lamblin,Henichart
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- A defense Mechanism against Pathogenic Bacteria in the Digestive Tracts of Silkworm Larvae-in vitro Evidence of the Formation of Caffeoquinone, a True Antibacterial Substance, and Synergism of Amino Compounds
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For the defense mechanism against pathogenic bacteria in the digestive tracts of silkworm larvae reared on mulberry leaves, in vitro evidence of the formation of atrue antibacterial substance was obtained. caffeic acid (CA) derived from chlorogenic acid (ChA)was converted into caffeoquinone (CQ) by base-catalyzed oxidation in a buffer solution (pH 10.0).CQ was trapped as 6'phenylsulfonylcaffeic acid (6'sulfone) by the addition of benzenesulfinic acid (BSA).The synergetic effects of amino compounds on the antibacterial activity of CQ are discussed in detail, and the probable reactions of CA with amino and thiol compounds in the alkaline solution are proposed.
- Nakano, Hidenori,Tahara, Satoshi,Iizuka, Toshihiko,Mizutani, Junya
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p. 549 - 556
(2007/10/02)
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- Synthesis of N2-Protected L-2,3-Diaminopropanoic Acids
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The title compounds have been synthesized from N-protected L-aspartic acid via Curtis rearrangement.
- Noguchi, Noriyoshi,Kuroda, Tsuyoshi,Hatanaka, Minoru,Ishimaru, Toshiyasu
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p. 633 - 634
(2007/10/02)
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