25608-40-6Relevant academic research and scientific papers
NEW CHIRAL SYNTHON OF ELECTROPHILIC GLYCINE AND ITS REACTIONS WITH METALLOORGANIC, C-H, N-H, AND O-H COMPOUNDS FOR THE ASYMMETRIC SYNTHESIS OF α-SUBSTITUTED α-AMINOACIDS
Belokon', Yu. N.,Popkov, A. N.,Chernoglazova, N. I.,Bakhmutov, V. I.,Saporovskaya, M. B.,Belikov, V. M.
, p. 1744 - 1748 (1989)
A new chiral synthon of the electrophilic glycine - the Ni(II) complex of the Schiff base of L-N-benzylprolylorthoaminobenzophenone with α-bromoglycine - was synthesized.The reaction of this complex with nucleophiles led to the isolation of complexes of L- and D-2-amino-2-dimethylaminoacetic acid, L- and D-2-amino-2-phenoxyacetic acid, 3,3-di(carbethoxy)alanine, and norleucine.The decomposition of the 3,3-di(carbethoxy)alanine and norleucine complexes led to the synthesis of L-aspartic acid and L-norleucine with the enantiomeric purity of 80 and 68 percent correspondingly.
Stability of L-asparaginase: An enzyme used in leukemia treatment
Stecher,Morgantetti De Deus,Polikarpov,Abrahao-Neto
, p. 1 - 9 (1999)
L-asparaginase from Escherichia coli is an important enzyme widely used in leukemia treatment under the trade name Elspar. Up to now, however, the aspects of its stability and storage has not been studied in detail. The aim of this work is to analyze the factors that could interfere in the enzyme's stability. The enzymatic activity was found to be stable in wide pH range (4.5-11.5), showing a slight increase in activity and stability in alkaline pHs, which indicates a more stable conformation of the molecule. The enzyme proved to have a high activity restoration capacity when submitted to temperatures of 65°C, in pH 8.6 buffer and, surprisingly, in physiologic solution. This suggests a positive effect of sodium ions on such restoration capacity. Stability was high in different diluents used as parenteral solutions and in recipients used in medical practice without significant loss of activity for at least 7 days. These results lead us to conclude that the enzyme has a high stability after the lyophilized form has been reconstituted (at least 7 days), since the necessary precautions are taken in terms of sterile manipulation and if it is stored in a suitable parenteral vehicle under low temperature (about 8°C). Copyright (C) 1999 Elsevier Science B.V.
Engineering methylaspartate ammonia lyase for the asymmetric synthesis of unnatural amino acids
Raj, Hans,Szymanski, Wiktor,De Villiers, Jandre,Rozeboom, Henriette J.,Veetil, Vinod Puthan,Reis, Carlos R.,De Villiers, Marianne,Dekker, Frank J.,De Wildeman, Stefaan,Quax, Wim J.,Thunnissen, Andy-Mark W.H.,Feringa, Ben L.,Janssen, Dick B.,Poelarends, Gerrit J.
, p. 478 - 484 (2012)
The redesign of enzymes to produce catalysts for a predefined transformation remains a major challenge in protein engineering. Here, we describe the structure-based engineering of methylaspartate ammonia lyase (which in nature catalyses the conversion of 3-methylaspartate to ammonia and 2-methylfumarate) to accept a variety of substituted amines and fumarates and catalyse the asymmetric synthesis of aspartic acid derivatives. We obtained two single-active-site mutants, one exhibiting a wide nucleophile scope including structurally diverse linear and cyclic alkylamines and one with broad electrophile scope including fumarate derivatives with alkyl, aryl, alkoxy, aryloxy, alkylthio and arylthio substituents at the C2 position. Both mutants have an enlarged active site that accommodates the new substrates while retaining the high stereo- and regioselectivity of the wild-type enzyme. As an example, we demonstrate a highly enantio- and diastereoselective synthesis of threo-3-benzyloxyaspartate (an important inhibitor of neuronal excitatory glutamate transporters in the brain).
Engineering of helicobacter pylori lasparaginase: Characterization of two functionally distinct groups of mutants e0117025
Maggi, Maristella,Chiarelli, Laurent R.,Valentini, Giovanna,Scotti, Claudia
, (2015)
Bacterial L-asparaginases have been used as anti-cancer drugs for over 4 decades though presenting, along with their therapeutic efficacy, several side effects due to their bacterial origin and, seemingly, to their secondary glutaminase activity. Helicobacter pylori type II L-asparaginase possesses interesting features, among which a reduced catalytic efficiency for L-GLN, compared to the drugs presently used in therapy. In the present study, we describe some enzyme variants with catalytic and in vitro cytotoxic activities different from the wild type enzyme. Particularly, replacements on catalytic threonines (T16D and T95E) deplete the enzyme of both its catalytic activities, once more underlining the essential role of such residues. One serendipitous mutant, M121C/T169M, had a preserved efficiency vs L-asparagine but was completely unable to carry out L-glutamine hydrolysis. Interestingly, this variant did not exert any cytotoxic effect on HL-60 cells. The M121C and T169M single mutants had reduced catalytic activities (nearly 2.5- to 4-fold vs wild type enzyme, respectively). Mutant Q63E, endowed with a similar catalytic efficiency versus asparagine and halved glutaminase efficiency with respect to the wild type enzyme, was able to exert a cytotoxic effect comparable to, or higher than, the one of the wild type enzyme when similar asparaginase units were used. These findings may be relevant to determine the role of glutaminase activity of L-asparaginase in the anti-proliferative effect of the drug and to shed light on how to engineer the best asparaginase/glutaminase combination for an ever improved, patients-tailored therapy.
The concept of internal solubilization in peptide synthesis: ethylene glycol-based protecting groups
Kocsis, László,Bruckdorfer, Thomas,Orosz, Gy?rgy
, p. 7015 - 7017 (2008)
A novel, ethylene glycol-based protecting group is designed and synthesized for use in solid phase peptide synthesis. Ether and ester type protected amino acids are prepared. The acid stability of the new protecting group showed complete Fmoc/t-Bu compatibility. The new derivatives are tested in solid phase peptide synthesis, with a 'difficult' sequence to examine the disruption of peptide aggregation.
Cloning, expression, and characterization of L-asparaginase from a newly isolated Bacillus subtilis B11-06
Jia, Mingmei,Xu, Meijuan,He, Beibei,Rao, Zhiming
, p. 9428 - 9434 (2013)
This study focused on the cloning, overexpression, and characterization of the gene encoding L-asparaginase (ansZ) from a nonpathogenic strain of Bacillus subtilis B11.06. The recombinant enzyme showed high thermostability and low affinity to L-glutamine. The ansZ gene, encoding a putative L-asparaginase II, was amplified by PCR and expressed in B. subtilis 168 using the shuttle vector pMA5. The activity of the recombinant enzyme was 9.98 U/mL, which was significantly higher than that of B. subtilis B11.06. The recombinant enzyme was purified by a two-step procedure including ammonium sulfate fractionation and hydrophobic interaction chromatography. The optimum pH and temperature of the recombinant enzyme were 7.5 and 40 °C, respectively. The enzyme was quite stable at a pH range of 6.0.9.0 and exhibited about 14.7 and 9.0% retention of activity following 2 h incubation at 50 or 60 °C, respectively. The K m for L-asparagine was 0.43 mM, and the Vmax was 77.51 μM/min. Results of this study also revealed the potential industrial application of this enzyme in reducing acrylamide formation during the potato frying process.
SYNTHESIS OF D,L-β-CARBOXYASPARTIC ACID FROM HYDANTOIN-5-MALONIC ACID DIETHYL ESTER
Henson, Edward B.,Gallop, Paul M.,Hauschka, Peter V.
, p. 2561 - 2562 (1981)
Hydantoin-5-malonic acid diethyl ester was synthesized by reduction of parabanic acid (oxalyl urea) to 5-hydroxy-hydantoin, conversion to 5-chlorohydantoin and condensation with malonic ester.Alkaline hydrolysis gave D,L-β-carboxyaspartic acid.
Biocatalytic enantioselective synthesis of N-substituted aspartic acids by aspartate ammonia lyase
Weiner, Barbara,Poelarends, Gerrit J.,Janssen, Dick B.,Feringa, Ben L.
, p. 10094 - 10100 (2008)
The gene encoding aspartate ammonia lyase (asp B) from Bacillus sp. YM55-1 has been cloned and over-expressed, and the recombinant enzyme containing a C-terminal HiS6 tag has been purified to homogeneity and subjected to kinetic characterization. Kinetic studies have shown that the HiS6 tag does not affect AspB activity. The enzyme processes L-aspartic acid, but not D-aspartic acid, with a km of ≈15 mM and a Kcat, of ≈ 40s-1. By using this recombinant enzyme in the reverse reaction, a set of four N-substituted aspartic acids were prepared by the Michael addition of hydroxylamine, hydrazine, methoxylamine, and methylamine to fumarate. Both hydroxylamine and hydrazine were found to be excellent substrates for AspB. The kcat values are comparable to those observed for the AspB-catalyzed addition of ammonia to fumarate (≈90 s-1), whereas the Km values are only slightly higher. The products of the enzyme-catalyzed addition of hydrazine, methoxylamine, and methylamine to fumarate were isolated and characterized by NMR spectroscopy and HPLC analysis, which revealed that AspB catalyzes all the additions with excellent enantioselectivity (>97% ee). Its broad nucleophile specificity and high catalytic activity make AspB an attractive enzyme for the enantioselective synthesis of N-substituted aspartic acids, which are interesting building blocks for peptide and pharmaceutical synthesis as well as for peptidomimetics.
Induction of cryptic metabolites of the endophytic fungus: Trichocladium sp. through OSMAC and co-cultivation
Tran-Cong, Nam Michael,Mándi, Attila,Kurtán, Tibor,Müller, Werner E.G.,Kalscheuer, Rainer,Lin, Wenhan,Liu, Zhen,Proksch, Peter
, p. 27279 - 27288 (2019)
The endophytic fungus Trichocladium sp. isolated from roots of Houttuynia cordata was cultured on solid rice medium, yielding a new amidepsine derivative (1) and a new reduced spiro azaphilone derivative (3) together with eight known compounds (4-11). Co-cultivation of Trichocladium sp. with Bacillus subtilis resulted in induction of a further new compound (2) and a 10-fold increase of 11 compared to the axenic fungal culture. Moreover, when the fungus was cultivated on peas instead of rice, a new sesquiterpene derivative (13) and two known compounds (12 and 14) were obtained. Addition of 2% tryptophan to rice medium led to the isolation of a new bismacrolactone (15). The structures of the new compounds were elucidated by HRESIMS, 1D and 2D NMR as well as by comparison with the literature. A combination of TDDFT-ECD, TDDFT-SOR, DFT-VCD and DFT-NMR calculations were applied to determine the absolute and relative configurations of 13 and 15. Compounds 7, 11 and 15 exhibited strong cytotoxicity against the L5178Y mouse lymphoma cell line with IC50 values of 0.3, 0.5 and 0.2 μM, respectively.
Two new β-carboline alkaloids from the roots of Gypsophila oldhamiana
Zhang, Yangmei,Wang, Gang,Lv, Huawei,Luo, Jianguang,Kong, Lingyi
, p. 1207 - 1211 (2015)
Phytochemical investigation of the roots of Gypsophila oldhamiana afforded two new β-carboline alkaloids, oldhamiaines A and B (1 and 2), along with a known analogue (3). Their structures were elucidated by using spectroscopic and chemical methods. This is the first report of β-carboline alkaloids in the genus Gypsophila.
