18875-37-1Relevant academic research and scientific papers
Synthesis and Reaction of a New Chiral Pyridoxamine Analogue; Some Doubt about the Stereochemical Process Tentatively Proposed for a Nonenzymatic Transamination Reaction
Ando, Makoto,Kuzuhara, Hiroyoshi
, p. 244 - 250 (1989)
A pyridoxamine analogue-like chiral pyridinophane with two sulfonyl groups in the bridging chain, (S)-15-aminomethyl-14-hydroxy-2,8-dithia(2,5)pyridinophane S,S,S',S'-tetraoxide ((S)-7), was prepared by oxidation of the sulfide precursor, (S)-2.The amino group was successfully transferred from (S)-7 to several 2-oxo carboxylic acids in methanol at room temperature in the presence of one-half equimolecular zinc(II) ion, giving (R)-amino acids in excess.The reaction rates of this nonenzymatic transamination using chiral (S)-7 were much smaller than those of the corresponding reaction using chiral (S)-2.The enantiomeric excess of the amino acids obtained through the reactions of (S)-7 was compared with those of (S)-2, showing that (S)-7-was more efficient than (S)-2 for the preparation of (R)-alanine, but was less than that of (S)-2 for the preparations of (R)-valine, (R)-leucine, and (R)-phenylalanine.These results aroused some doubt about the previous explanation of the stereochemical features of such nonenzymatic transamination reactions.
Real-time monitoring of D-Ala-D-Ala dipeptidase activity of VanX in living bacteria by isothermal titration calorimetry
Lv, Miao,Zhang, Yue-Juan,Zhou, Fan,Ge, Ying,Zhao, Mu-Han,Liu, Ya,Yang, Ke-Wu
, p. 29 - 35 (2019)
The D,D-dipeptidase enzyme VanX is the main cause of vancomycin resistance in gram-positive bacteria because of hydrolysis of the D-Ala-D-Ala dipeptide used in cell-wall biosynthesis. Continuous assay of VanX has proven challenging due to lack of a chromophoric substrate. Here, we report a direct approach for continuous assay of VanX in vitro and in vivo from hydrolysis of D-Ala-D-Ala, based on the heat-rate changes measured with isothermal titration calorimetry (ITC). With the ITC approach, determination of kinetic parameters of VanX hydrolyzing D-Ala-D-Ala and the inhibition constant of D-cysteine inhibitor yielded KM of 0.10 mM, kcat of 11.5 s?1, and Ki of 18.8 μM, which are consistent with the data from ninhydrin/Cd(II)assays. Cell-based ITC studies demonstrated that the VanX expressed in E. coli and in clinical strain VRE was inhibited by D-cysteine with IC50 values of 29.8 and 28.6 μM, respectively. Also, the total heat from D-Ala-D-Ala (4 mM)hydrolysis decreases strongly (in absolute value)from 1.26 mJ for VRE to 0.031 mJ for E. faecalis, which is consistent with the large MIC value of vancomycin of 512 μg/mL for VRE and the much smaller value of 4 μg/mL for E. faecalis. The ITC approach proposed here could be applied to screen and evaluate small molecule inhibitors of VanX or to identify drug resistant bacteria.
Dioncophylline E from Dioncophyllum thollonii, the first 7,3′-coupled dioncophyllaceous naphthylisoquinoline alkaloid
Bringmann, Gerhard,Messer, Kim,Wolf, Kristina,Muehlbacher, Joerg,Gruene, Matthias,Brun, Reto,Louis, Adriaan M.
, p. 389 - 397 (2002)
The isolation and structural elucidation of dioncophylline E, a novel naphthylisoquinoline alkaloid from the rare West African liana Dioncophyllwn thollonii, is described. The alkaloid displays an unusual 7,3′-linkage between the naphthalene and the isoquinoline portions. Due to the resulting medium degree of steric hindrance exerted by the ortho-substituents next to the biaryl axis, the compound undergoes slow rotation about the axis at room temperature and thus is the first such alkaloid that occurs as a mixture of two configurationally semi-stable atropo-diastereomers. Dioncophylline E exhibits good antimalarial activity against both chloroquine-sensitive and -resistant strains of Plasmodium falciparum while its antitrypanosomal activity against Trypanosoma cruzi is weak and that against T. brucei rhodesiense is moderate. Furthermore, four additional naphthylisoquinoline alkaloids previously known from the related plant species Triphyophyllum peltatum, have been identified in D. thollonii.
Hydrolysis of acetyl-methionine-containing dipeptides promoted by palladium(II) complexes containing methionine-amino acids as ligands
Luo, Xuemei,Chen, Xiaohua,Song, Yongcheng,Zhu, Longgen
, p. 1079 - 1080 (1998)
The [Pd(N,S-Met-a'a'H)(N,S-AcMet-aaH)] (a'a'H and aaH = amino acids) was characterized by electrospray ionization mass spectrometer(ESI-MS) and 1H NMR, in which Met-a'a'H, as ligand, coordinates to Pd(II) via thioether and terminal amino group, and AcMet-aaH, as substrate, coordinates to Pd(II) via thioether and deprotonated amide nitrogen of methionine. The Met-a'a' bond in ligand is intact, the Met-aa bond in substrate, however, is activated toward hydrolysis The difference in hydrolysis behavior between ligand and substrate may be due to a fused six-membered and five-membered ring formation via thioether, deprotonated amide nitrogen and carbonyl oxygen of methionine residue in substrate.
Polyoxypeptin isolated from Streptomyces: A bioactive cyclic depsipeptide containing the novel amino acid 3-hydroxy-3-methylproline
Umezawa, Kazuo,Nakazawa, Kumi,Uemura, Toshio,Ikeda, Yoko,Kondo, Shinichi,Naganawa, Hiroshi,Kinoshita, Naoko,Hashizume, Hideki,Hamada, Masa,Takeuchi, Tomio,Ohba, Shigeru
, p. 1389 - 1392 (1998)
Polyoxypeptin, a potent inducer of apoptosis in human pancreatic carcinoma cells, was isolated from an ethyl acetate extract of a Streptomyces culture broth. Structural determination by 2D-NMR and X-ray crystallographic analysis revealed that it is a novel cyclic hexadepsipeptide containing five hydroxylated amino acids. The unusual and hitherto unreported amino acid 3-hydroxy-3-methylproline was one of them.
Sinefungin VA and dehydrosinefungin V, new antitrypanosomal antibiotics produced by Streptomyces sp. K05-0178
Niitsuma, Megumi,Hashida, Junko,Iwatsuki, Masato,Mori, Mihoko,Ishiyama, Aki,Namatame, Miyuki,Nishihara-Tsukashima, Aki,Matsumoto, Atsuko,Takahashi, Yoko,Yamada, Haruki,Otoguro, Kazuhiko,Shiomi, Kazuro,Oemura, Satoshi
, p. 673 - 679 (2010)
Two new nucleotide antibiotics, named sinefungin VA and dehydrosinefungin V, were separated by cation exchange column chromatography and purified by HPLC from the culture broth of Streptomyces sp. K05-0178, together with the known antibiotics, sinefungin, dehydrosinefungin and KSA-9342. The structures of the two novel sinefungin analogs were elucidated by spectroscopic studies, including various NMR and advanced peptide chemical methods. Sinefungin VA consists of adenosine and ornithylvalylalanine, whereas dehydrosinefungin V consists of 4′,5′-dehydroadenosine and ornithylvaline. Sinefungin VA showed potent antitrypanosomal activity with an IC50 value of 0.0026 g ml 1 in vitro without cytotoxicity against MRC-5 cells. Dehydrosinefungin V showed moderate antitrypanosomal activity (IC50=0.15 μg ml-1).
Sustainable synthesis of amino acids by catalytic fixation of molecular dinitrogen and carbon dioxide
Rivas, Manuel,Del Valle, Luís J.,Turon, Pau,Alemán, Carlos,Puiggalí, Jordi
, p. 685 - 693 (2018)
The industrial process of nitrogen fixation is complex and results in a huge economic and environmental impact. It requires a catalyst and high temperature and pressure to induce the rupture of the strong N-N bond and subsequent hydrogenation. On the other hand, carbon dioxide removal from the atmosphere has become a priority objective due to the high amount of global carbon dioxide emissions (i.e. 36 200 million tons in 2015). In this work, we fix nitrogen from N2 and carbon from CO2 and CH4 to obtain both glycine and alanine (d/l racemic mixture), the two simplest amino acids. The synthesis, catalyzed by polarized hydroxyapatite under UV light irradiation and conducted in an inert reaction chamber, starts from a simple gas mixture containing N2, CO2, CH4 and H2O and uses mild reaction conditions. At atmospheric pressure and 95 °C, the glycine and alanine molar yields with respect to CH4 or CO2 are about 1.9% and 1.6%, respectively, but they grow to 3.4% and 2.4%, when the pressure increases to 6 bar and the temperature is maintained at 95 °C. Besides, the minimum temperature required for the successful production of detectable amounts of amino acids is 75 °C. Accordingly, an artificial photosynthetic process has been developed by using an electrophotocatalyst based on hydroxyapatite thermally and electrically stimulated and coated with zirconyl chloride and a phosphonate. The synthesis of amino acids by direct fixation of nitrogen and carbon from gas mixtures opens new avenues regarding the nitrogen fixation for industrial purposes and the recycling of carbon dioxide.
Argifin, a new chitinase inhibitor, produced by Gliocladium sp. FTD-0668 II. Isolation, physico-chemical properties, and structure elucidation
Arai, Noriko,Shiomi, Kazuro,Iwai, Yuzuru,Oemura, Satoshi
, p. 609 - 614 (2000)
A new chitinase inhibitor, named argifin, was isolated from the cultured broth of a fungal strain Gliocladium sp. FTD-0668. Argifin was purified from the cultured mycelium by the combination of cation exchange, anion exchange, adsorption, and gel filtration Chromatographie methods. The structure of argifin was elucidated as cyclo(N-(β-methylcarbamoyl)-L-arginylN-methyl-L-phenyIalanyl-β-L- aspartyl-β-L-aspartyl-D-alanyl) by NMR experiments and other spectroscopic analyses.
Artificial metalloenzymes based on protein cavities: Exploring the effect of altering the metal ligand attachment position by site directed mutagenesis
Davies, Ronald R.,Kuang, Hao,Qi, Dongfeng,Mazhary, Aram,Mayaan, Evelyn,Distefano, Mark D.
, p. 79 - 84 (1999)
In an effort to construct catalysts with enzyme-like properties, we are employing a small, cavity-containing protein as a scaffold for the attachment of catalytic groups. In earlier work we demonstrated that a phenanthroline ligand could be introduced into the cavity of the protein ALBP and used to catalyze ester hydrolysis. To examine the effect of positioning the phenanthroline catalyst at different locations within the protein cavity, three new constucts - Phen60, Phen72 and Phen104 - were prepared. Each new conjugate was characterized by UV/vis spectroscopy, fluorescence spectroscopy, guanidine hydrochloride denaturation, gel filtration chromatography, and CD spectroscopy to confirm the preparation of the desired contruct. Analysis of reactions containing Ala-OiPr showed that Phen60 catalyzed ester hydrolysis with less selectivity than ALBP-Phen while Phen72 promoted this same reaction with higher selectivity. Reactions with Tyr-OMe were catalyzed with higher selectivity by Phen60 and more rapidly by Phen104. These results demonstrate that both the rates and selectivities of hydrolysis reactions catalyzed by these constructs are dependent on the precise site of attachment of the metal ligand within the protein cavity.
Alanine racemase of alfalfa seedlings (Medicago sativa L.): First evidence for the presence of an amino acid racemase in plants
Ono, Kazutoshi,Yanagida, Kazuki,Oikawa, Tadao,Ogawa, Tadashi,Soda, Kenji
, p. 856 - 860 (2006)
We demonstrated several kinds of d-amino acids in plant seedlings, and moreover alanine racemase (E.C.5.1.1.1) in alfalfa (Medicago sativa L.) seedlings. This is the first evidence for the presence of amino acid racemase in plant. The enzyme was effectively induced by the addition of l- or d-alanine, and we highly purified the enzyme to show enzymological properties. The enzyme exclusively catalyzed racemization of l- and d-alanine. The Km and Vmax values of enzyme for l-alanine were 29.6 × 10-3 M and 1.02 mol/s/kg, and those for d-alanine are 12.0 × 10-3 M and 0.44 mol/s/kg, respectively. The Keq value was estimated to be about 1 and indicated that the enzyme catalyzes a typical racemization of both enantiomers of alanine. The enzyme was inactivated by hydroxylamine, phenylhydrazine and some other pyridoxal 5′-phosphate enzyme inhibitors. Accordingly, the enzyme required pyridoxal 5′-phosphate as a coenzyme, and enzymologically resembled bacterial alanine racemases studied so far.
