The Synthesis of Optically Pure Epoxy-alkyl β-D-Glucosides and β-Cellobiosides as Active-Site Directed Inhibitors of Some β-Glucan Hydrolases

1990 ◽  
Vol 43 (8) ◽  
pp. 1391 ◽  
Author(s):  
EB Rodriguez ◽  
GD Scally ◽  
RV Stick
Keyword(s):  
Active Site ◽  
Optical Purity ◽  
Asymmetric Epoxidation ◽  
Chiral Alcohol ◽  
Pure Epoxy ◽  
Whole Process ◽  
High Optical Purity ◽  
The One ◽  
Sharpless Asymmetric Epoxidation ◽  
Optically Pure

(2R)- and (2S)-2,3-Epoxypropyl, (3R)- and (3S)-3,4-epoxybutyl and (4S)- 4,s-epoxypentyl B- Dglucopyranoside , together with the (3R)- and (3s)-3,4-epoxybutyl β- cellobiosides , have been prepared by condensation of a glycosyl bromide with the appropriate enantiomer of a chiral alcohol containing a diol protected as an isopropylidene acetal, and subsequent manipulation of the unmasked diol into the epoxide function. As well, in an improvement to the whole process, both diastereoisomers of the various epoxypropyl and epoxybutyl glycosides were available from just the one enantiomer of the alcohol by an alternative manipulation of the diol. Finally, precursors to 2,3-epoxy-4-hydroxybutyl β-D-glucosides and β- cellobiosides were prepared in high optical purity by Sharpless asymmetric epoxidation of the appropriate 4-hydroxybut-2-enyl glycosides.

Preparation of secondary alcohols of high optical purity

1986 ◽  
Vol 51 (2) ◽  
pp. 401-403 ◽  
Author(s):  
Otakar Červinka ◽  
Anna Fábryová ◽  
Irina Sablukova
Keyword(s):  
Nmr Spectroscopy ◽  
Optical Purity ◽  
Optically Active ◽  
Secondary Alcohols ◽  
Lithium Aluminium Hydride ◽  
Enantioselective Reduction ◽  
H Nmr ◽  
Lithium Aluminium ◽  
High Optical Purity ◽  
Optically Pure

Partially resolved enantiomers of optically active alcohols I-V, obtained by enantioselective reduction of the corresponding ketones with lithium aluminium hydride in the presence of (-)-quinine, were converted into crystalline 3,5-dinitrobenzoates or phenylcarbamates. The esters of the nearly optically pure enantiomers were separated by crystallization from the generally more soluble esters of the racemates. Optical purity of the hydrolytically liberated alcohols was determined by 1H NMR spectroscopy in the presence of chiral shifting agents.

scholarly journals Major Role of NAD-Dependent Lactate Dehydrogenases in the Production of l-Lactic Acid with High Optical Purity by the Thermophile Bacillus coagulans

2014 ◽  
Vol 80 (23) ◽  
pp. 7134-7141 ◽  
Author(s):  
Limin Wang ◽  
Yumeng Cai ◽  
Lingfeng Zhu ◽  
Honglian Guo ◽  
Bo Yu
Keyword(s):  
Lactic Acid ◽  
Lactate Dehydrogenase ◽  
Acid Production ◽  
Lactic Acid Production ◽  
Optical Purity ◽  
Bacillus Coagulans ◽  
Lactobacillus Delbrueckii ◽  
Content Type ◽  
High Optical Purity ◽  
Optically Pure

ABSTRACTBacillus coagulans2-6 is an excellent producer of optically purel-lactic acid. However, little is known about the mechanism of synthesis of the highly optically purel-lactic acid produced by this strain. Three enzymes responsible for lactic acid production—NAD-dependentl-lactate dehydrogenase (l-nLDH; encoded byldhL), NAD-dependentd-lactate dehydrogenase (d-nLDH; encoded byldhD), and glycolate oxidase (GOX)—were systematically investigated in order to study the relationship between these enzymes and the optical purity of lactic acid.Lactobacillus delbrueckiisubsp.bulgaricusDSM 20081 (ad-lactic acid producer) andLactobacillus plantarumsubsp.plantarumDSM 20174 (adl-lactic acid producer) were also examined in this study as comparative strains, in addition toB. coagulans. The specific activities of key enzymes for lactic acid production in the three strains were characterizedin vivoandin vitro, and the levels of transcription of theldhL,ldhD, and GOX genes during fermentation were also analyzed. The catalytic activities ofl-nLDH andd-nLDH were different inl-,d-, anddl-lactic acid producers. Onlyl-nLDH activity was detected inB. coagulans2-6 under native conditions, and the level of transcription ofldhLinB. coagulans2-6 was much higher than that ofldhDor the GOX gene at all growth phases. However, for the twoLactobacillusstrains used in this study,ldhDtranscription levels were higher than those ofldhL. The high catalytic efficiency ofl-nLDH toward pyruvate and the high transcription ratios ofldhLtoldhDandldhLto the GOX gene provide the key explanations for the high optical purity ofl-lactic acid produced byB. coagulans2-6.

scholarly journals Ground-State Destabilization by Active-Site Hydrophobicity Controls the Selectivity of a Cofactor- Free Decarboxylase

2020 ◽  
Author(s):  
Michal Biler ◽  
Rory Crean ◽  
Anna K. Schweiger ◽  
Robert Kourist ◽  
Shina Caroline Lynn Kamerlin
Keyword(s):  
Ground State ◽  
Active Site ◽  
Valence Bond ◽  
Optical Purity ◽  
Interaction Network ◽  
Enzyme Engineering ◽  
Carboxylate Group ◽  
Solvent Exposure ◽  
Preferential Cleavage ◽  
High Optical Purity

<div> <div> <p> </p><div> <div> <div> <p>Bacterial arylmalonate decarboxylase (AMDase) and evolved variants have become a valuable tool with which to access both enantiomers of a broad range of chiral arylaliphatic acids with high optical purity. Yet, the molecular principles responsible for the substrate scope, activity and selectivity of this enzyme are only poorly understood to this day, greatly hampering the predictability and design of improved enzyme variants for specific applications. In this work, empirical valence bond and metadynamics simulations were performed on wild-type AMDase and variants thereof, to obtain a better understanding of the underlying molecular processes determining reaction outcome. Our results clearly reproduce the experimentally observed substrate scope, and support a mechanism driven by ground-state destabilization of the carboxylate group being cleaved by the enzyme. In addition, our results indicate that, in the case of the non-converted or poorly-converted substrates studied in this work, increased solvent exposure of the active site upon binding of these substrates can disturb the vulnerable network of interactions responsible for facilitating the AMDase-catalyzed cleavage of CO2. Finally, our results indicate a switch from preferential cleavage of the pro-(R) to the pro-(S) carboxylate group in the CLG-IPL variant of AMDase for all substrates studied. This appears to be due to the emergence of a new hydrophobic pocket generated by the insertion of the six amino acid substitutions, into which the pro-(S) carboxylate binds. Our results allow insight into the tight interaction network determining AMDase selectivity, which in turn provides guidance for the identification of target residues for future enzyme engineering. </p> </div> </div> </div> </div> </div>

scholarly journals Synthesis of the Enantiomers of Thioridazine

SynOpen ◽  
2020 ◽  
Vol 04 (01) ◽  
pp. 12-16 ◽  
Author(s):  
Simen Antonsen ◽  
Erling B. Monsen ◽  
Kirill Ovchinnikov ◽  
Jens M. J. Nolsøe ◽  
Dag Ekeberg ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Optical Purity ◽  
Scaling Up ◽  
Racemic Mixture ◽  
Bacterial Strains ◽  
Beneficial Effects ◽  
High Optical Purity ◽  
Primary Indication ◽  
Optically Pure

Thioridazine, a well-known antipsychotic drug, has shown promising effects on several bacterial strains (including Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus). Suppressive effects towards selected cancer cell-lines have also been reported. However, due to adverse effects, the compound is no longer in use for the primary indication. More recent research has demonstrated that these side effects are limited to one of the two enantiomers, (+)-thioridazine. The question arises to whether the beneficial effects of thioridazine are limited to one enantiomer, or if (–)-thioridazine can prove itself to be useful in its pure enantiomeric state. The published procedures on the synthesis of the optically pure enantiomers of thioridazine were found to be unsatisfactory, either due to low optical purity, high cost, or problems scaling up. Herein, we have used an auxiliary-based strategy for the total synthesis of both enantiomers in high optical purity and good overall yield. The strategy can easily be scaled up. Both enantiomers were tested against several bacteria. Comparison of the racemic mixture, (–)-thioridazine and its (+)-antipode revealed that they have the same antimicrobial effects. Thus, the non-toxic enantiomer, (–)-thioridazine, can prove useful in this role and should be investigated further.

scholarly journals Ground-State Destabilization by Active-Site Hydrophobicity Controls the Selectivity of a Cofactor- Free Decarboxylase

2020 ◽  
Author(s):  
Michal Biler ◽  
Rory Crean ◽  
Anna K. Schweiger ◽  
Robert Kourist ◽  
Shina Caroline Lynn Kamerlin
Keyword(s):  
Ground State ◽  
Active Site ◽  
Valence Bond ◽  
Optical Purity ◽  
Interaction Network ◽  
Enzyme Engineering ◽  
Carboxylate Group ◽  
Solvent Exposure ◽  
Preferential Cleavage ◽  
High Optical Purity

<div> <div> <p> </p><div> <div> <div> <p>Bacterial arylmalonate decarboxylase (AMDase) and evolved variants have become a valuable tool with which to access both enantiomers of a broad range of chiral arylaliphatic acids with high optical purity. Yet, the molecular principles responsible for the substrate scope, activity and selectivity of this enzyme are only poorly understood to this day, greatly hampering the predictability and design of improved enzyme variants for specific applications. In this work, empirical valence bond and metadynamics simulations were performed on wild-type AMDase and variants thereof, to obtain a better understanding of the underlying molecular processes determining reaction outcome. Our results clearly reproduce the experimentally observed substrate scope, and support a mechanism driven by ground-state destabilization of the carboxylate group being cleaved by the enzyme. In addition, our results indicate that, in the case of the non-converted or poorly-converted substrates studied in this work, increased solvent exposure of the active site upon binding of these substrates can disturb the vulnerable network of interactions responsible for facilitating the AMDase-catalyzed cleavage of CO2. Finally, our results indicate a switch from preferential cleavage of the pro-(R) to the pro-(S) carboxylate group in the CLG-IPL variant of AMDase for all substrates studied. This appears to be due to the emergence of a new hydrophobic pocket generated by the insertion of the six amino acid substitutions, into which the pro-(S) carboxylate binds. Our results allow insight into the tight interaction network determining AMDase selectivity, which in turn provides guidance for the identification of target residues for future enzyme engineering. </p> </div> </div> </div> </div> </div>

scholarly journals Ground-State Destabilization by Active-Site Hydrophobicity Controls the Selectivity of a Cofactor- Free Decarboxylase

2020 ◽  
Author(s):  
Michal Biler ◽  
Rory Crean ◽  
Anna K. Schweiger ◽  
Robert Kourist ◽  
Shina Caroline Lynn Kamerlin
Keyword(s):  
Ground State ◽  
Active Site ◽  
Valence Bond ◽  
Optical Purity ◽  
Interaction Network ◽  
Enzyme Engineering ◽  
Carboxylate Group ◽  
Solvent Exposure ◽  
Preferential Cleavage ◽  
High Optical Purity

<div> <div> <p> </p><div> <div> <div> <p>Bacterial arylmalonate decarboxylase (AMDase) and evolved variants have become a valuable tool with which to access both enantiomers of a broad range of chiral arylaliphatic acids with high optical purity. Yet, the molecular principles responsible for the substrate scope, activity and selectivity of this enzyme are only poorly understood to this day, greatly hampering the predictability and design of improved enzyme variants for specific applications. In this work, empirical valence bond and metadynamics simulations were performed on wild-type AMDase and variants thereof, to obtain a better understanding of the underlying molecular processes determining reaction outcome. Our results clearly reproduce the experimentally observed substrate scope, and support a mechanism driven by ground-state destabilization of the carboxylate group being cleaved by the enzyme. In addition, our results indicate that, in the case of the non-converted or poorly-converted substrates studied in this work, increased solvent exposure of the active site upon binding of these substrates can disturb the vulnerable network of interactions responsible for facilitating the AMDase-catalyzed cleavage of CO2. Finally, our results indicate a switch from preferential cleavage of the pro-(R) to the pro-(S) carboxylate group in the CLG-IPL variant of AMDase for all substrates studied. This appears to be due to the emergence of a new hydrophobic pocket generated by the insertion of the six amino acid substitutions, into which the pro-(S) carboxylate binds. Our results allow insight into the tight interaction network determining AMDase selectivity, which in turn provides guidance for the identification of target residues for future enzyme engineering. </p> </div> </div> </div> </div> </div>

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