Reshaping the Active Pocket of Esterase Est816 for Resolution of Economically Important Racemates

2021 ◽  
Author(s):  
Xiaolong Liu ◽  
Meng Zhao ◽  
Xinjiong Fan ◽  
Yao Fu
Keyword(s):  
Substrate Specificity ◽  
Industrial Applications ◽  
Pure Compounds ◽  
Optically Pure ◽  
Wide Substrate Specificity

One of the most important industrial applications of bacterial esterases is the production of optically pure compounds. However, the contradiction between the wide substrate specificity and high enantioselectivity of natural...

scholarly journals Altering the Stereoselectivity of Whole-Cell Biotransformations via the Physicochemical Parameters Impacting the Processes

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 781
Author(s):  
Agnieszka Raczyńska ◽  
Joanna Jadczyk ◽  
Małgorzata Brzezińska-Rodak
Keyword(s):  
Culture Conditions ◽  
Biologically Active ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
Chiral Compounds ◽  
Physicochemical Factors ◽  
Pure Compounds ◽  
Genetic Level ◽  
Prochiral Ketones ◽  
Optically Pure

The enantioselective synthesis of organic compounds is one of the great challenges in organic synthetic chemistry due to its importance for the acquisition of biologically active derivatives, e.g., pharmaceuticals, agrochemicals, and others. This is why biological systems are increasingly applied as tools for chiral compounds synthesis or modification. The use of whole cells of “wild-type” microorganisms is one possible approach, especially as some methods allow improving the conversion degrees and controlling the stereoselectivity of the reaction without the need to introduce changes at the genetic level. Simple manipulation of the culture conditions, the form of a biocatalyst, or the appropriate composition of the biotransformation medium makes it possible to obtain optically pure products in a cheap, safe, and environmentally friendly manner. This review contains selected examples of the influence of physicochemical factors on the stereochemistry of the biocatalytic preparation of enantiomerically pure compounds, which is undertaken through kinetically controlled separation of their racemic mixtures or reduction of prochiral ketones and has an effect on the final enantiomeric purity and enantioselectivity of the reaction.

scholarly journals Analysis of Sequence Divergence in Mammalian ABCGs Predicts a Structural Network of Residues That Underlies Functional Divergence

2021 ◽  
Vol 22 (6) ◽  
pp. 3012
Author(s):  
James I. Mitchell-White ◽  
Thomas Stockner ◽  
Nicholas Holliday ◽  
Stephen J. Briddon ◽  
Ian D. Kerr
Keyword(s):  
Substrate Specificity ◽  
Functional Divergence ◽  
3D Structure ◽  
Sequence Divergence ◽  
Conformational Flexibility ◽  
Substrate Selectivity ◽  
Multiple Sequence ◽  
Atp Binding Cassette Transporters ◽  
Structural Network ◽  
Wide Substrate Specificity

The five members of the mammalian G subfamily of ATP-binding cassette transporters differ greatly in their substrate specificity. Four members of the subfamily are important in lipid transport and the wide substrate specificity of one of the members, ABCG2, is of significance due to its role in multidrug resistance. To explore the origin of substrate selectivity in members 1, 2, 4, 5 and 8 of this subfamily, we have analysed the differences in conservation between members in a multiple sequence alignment of ABCG sequences from mammals. Mapping sets of residues with similar patterns of conservation onto the resolved 3D structure of ABCG2 reveals possible explanations for differences in function, via a connected network of residues from the cytoplasmic to transmembrane domains. In ABCG2, this network of residues may confer extra conformational flexibility, enabling it to transport a wider array of substrates.

scholarly journals Metallohelices that kill Gram-negative pathogens using intracellular antimicrobial peptide pathways

2019 ◽  
Vol 10 (42) ◽  
pp. 9708-9720 ◽  
Author(s):  
Daniel H. Simpson ◽  
Alexia Hapeshi ◽  
Nicola J. Rogers ◽  
Viktor Brabec ◽  
Guy J. Clarkson ◽  
...  
Keyword(s):  
Antimicrobial Peptide ◽  
Small Peptides ◽  
Gram Negative ◽  
Pure Compounds ◽  
Iron Based ◽  
Self Assembled ◽  
Optically Pure

Iron-based self-assembled optically pure compounds mimic the mechanisms of small peptides, according to biophysical, genomic, transcriptomic and other analyses.

One-pot kinetic resolution–Mitsunobu reaction to access optically pure compounds, using silver salts in the substitution protocol

2020 ◽  
Vol 44 (48) ◽  
pp. 21238-21243
Author(s):  
Hiten B. Raval ◽  
Ashutosh V. Bedekar
Keyword(s):  
Kinetic Resolution ◽  
Mitsunobu Reaction ◽  
One Pot ◽  
Silver Salts ◽  
Pure Compounds ◽  
Optically Pure

Racemic carbinols were converted to chirally pure acetates by a combination of one-pot, enzyme mediated KR and Mitsunobu reaction with metal acetates. Use of AoNO3 or mixture with NaOAc gave excellent results. The protocol is further extended to introduce azide in place of acetate.

scholarly journals Purification and Characterization of a Novel Mannitol Dehydrogenase from a Newly Isolated Strain of Candida magnoliae

2003 ◽  
Vol 69 (8) ◽  
pp. 4438-4447 ◽  
Author(s):  
Jung-Kul Lee ◽  
Bong-Seong Koo ◽  
Sang-Yong Kim ◽  
Hyung-Hwan Hyun
Keyword(s):  
Substrate Specificity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Catalytic Efficiency ◽  
Industrial Applications ◽  
Amino Acid Sequences ◽  
Size Exclusion ◽  
Mannitol Dehydrogenase ◽  
High Substrate ◽  
Candida Magnoliae

ABSTRACT Mannitol biosynthesis in Candida magnoliae HH-01 (KCCM-10252), a yeast strain that is currently used for the industrial production of mannitol, is catalyzed by mannitol dehydrogenase (MDH) (EC 1.1.1.138). In this study, NAD(P)H-dependent MDH was purified to homogeneity from C. magnoliae HH-01 by ion-exchange chromatography, hydrophobic interaction chromatography, and affinity chromatography. The relative molecular masses of C. magnoliae MDH, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography, were 35 and 142 kDa, respectively, indicating that the enzyme is a tetramer. This enzyme catalyzed both fructose reduction and mannitol oxidation. The pH and temperature optima for fructose reduction and mannitol oxidation were 7.5 and 37°C and 10.0 and 40°C, respectively. C. magnoliae MDH showed high substrate specificity and high catalytic efficiency (k cat = 823 s−1, K m = 28.0 mM, and k cat /K m = 29.4 mM−1 s−1) for fructose, which may explain the high mannitol production observed in this strain. Initial velocity and product inhibition studies suggest that the reaction proceeds via a sequential ordered Bi Bi mechanism, and C. magnoliae MDH is specific for transferring the 4-pro-S hydrogen of NADPH, which is typical of a short-chain dehydrogenase reductase (SDR). The internal amino acid sequences of C. magnoliae MDH showed a significant homology with SDRs from various sources, indicating that the C. magnoliae MDH is an NAD(P)H-dependent tetrameric SDR. Although MDHs have been purified and characterized from several other sources, C. magnoliae MDH is distinguished from other MDHs by its high substrate specificity and catalytic efficiency for fructose only, which makes C. magnoliae MDH the ideal choice for industrial applications, including enzymatic synthesis of mannitol and salt-tolerant plants.

N-Methylamino acids in peptide synthesis. VII. Studies on the enantiomeric purity of N-methylamino acids prepared by various procedures

1977 ◽  
Vol 55 (5) ◽  
pp. 916-921 ◽  
Author(s):  
S. T. Cheung ◽  
N. Leo Benoiton
Keyword(s):  
Amino Acid ◽  
Methyl Iodide ◽  
Peptide Synthesis ◽  
Liquid Ammonia ◽  
Silver Oxide ◽  
Sodium Hydride ◽  
Enantiomeric Purity ◽  
Amino Acid Analyzer ◽  
Pure Compounds ◽  
Optically Pure

The enantiomeric purity of N-methylamino acids and their derivatives obtained by various procedures has been examined by analysis with an amino-acid analyzer of the diastereomeric lysyl dipeptides formed by coupling them with a lysyl derivative. N-Benzyloxycarbonyl, and N-tert-butyloxycarbonyl,N-methylamino acids obtained by methylation of the parent derivative using sodium hydride and methyl iodide, and N-methylamino acids obtained by methylation of the p-toluenesulfonylamino acid followed by treatment with sodium in liquid ammonia, are optically pure. Compounds obtained by other procedures which include reductive alkylations or the use of silver oxide – methyl iodide are generally not optically pure.

scholarly journals Stereoselective synthesis of substituted 2,5-diazabicyclo[2.2.1]heptanes by iodine-mediated cyclization of optically pure compounds containing the 4,5-diamino-1,7-octadiene and 1,2-diamino-4-alkene moieties

Tetrahedron ◽  
2007 ◽  
Vol 63 (50) ◽  
pp. 12446-12453 ◽  
Author(s):  
Giuseppe Alvaro ◽  
Romano Di Fabio ◽  
Andrea Gualandi ◽  
Claudio Fiorelli ◽  
Magda Monari ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Pure Compounds ◽  
Optically Pure

scholarly journals Isolation and Absolute Configurations of Diversiform C17, C21 and C25 Terpenoids from the Marine Sponge Cacospongia sp.

Marine Drugs ◽  
2018 ◽  
Vol 17 (1) ◽  
pp. 14 ◽  
Author(s):  
Xingwang Zhang ◽  
Ping-Lin Li ◽  
Guo-Fei Qin ◽  
Shengying Li ◽  
Nicole de Voogd ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Cell Lines ◽  
Optical Rotation ◽  
Human Tumor ◽  
Chiral Hplc ◽  
Pure Compounds ◽  
New Compounds ◽  
First Time ◽  
Optically Pure ◽  
Circular Dichroïsm

Chemical investigation of MeOH extract of a South China Sea sponge Cacospongia sp. yielded 15 terpenoids belonging to three different skeleton-types, including the unusual C17 γ-lactone norditerpenoids (1–3), the rare C21 pyridine meroterpenoid (7), and the notable C25 manoalide-type sesterterpenoids (4–6, 8–10). Compounds 1–5 were initially obtained as enantiomers, and were further separated to be optically pure compounds (1a, 1b, 2a, 2b, 3a-r, 3b-r, 4a, 4b, 5a and 5b) by chiral HPLC, with a LiAlH4 reduction aid for 3. Compounds 3a/3b (a pair of inseparable enantiomers), 4a, 5a, 6, and 7 were identified as new compounds, while 1a/1b and 2a/2b were obtained from a natural source and were determined for their absolute configurations for the first time. This is also the first time to encounter enantiomers of the well-known manoalide-type sesterterpenoids from nature. The structures with absolute configurations of the new compounds were unambiguously determined by comprehensive methods including HR-ESI-MS and NMR data analysis, optical rotation comparison, experimental and calculated electronic circular dichroism (ECD), and Mo2(OAc)4 induced circular dichroism (ICD) methods. The cytotoxicity of the isolates against selected human tumor cell lines was evaluated, however, the tested compounds showed no activity against selected cell lines.

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