scholarly journals Demonstration of Redox Potential ofMetschnikowia koreensisfor Stereoinversion of Secondary Alcohols/1,2-Diols

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Vachan Singh Meena ◽  
Linga Banoth ◽  
U. C. Banerjee
Keyword(s):  
Substrate Specificity ◽  
Redox Potential ◽  
Optical Purity ◽  
Cofactor Regeneration ◽  
High Yield ◽  
Secondary Alcohols ◽  
One Pot ◽  
Wide Range ◽  
Multistep Reaction

The present work reports theMetschnikowia koreensis-catalyzed one-pot deracemization of secondary alcohols/1,2-diols and their derivatives with in vivo cofactor regeneration. Reaction is stereoselective and proceeds with sequential oxidation of (R)-secondary alcohols to the corresponding ketones and the reduction of the ketones to (S)-secondary alcohols. Method is applicable to a repertoire of racemic aryl secondary alcohols and 1,2-diols establishing a wide range of substrate specificity ofM. koreensis. This ecofriendly method afforded the product in high yield (88%) and excellent optical purity (>98%ee), minimizing the requirement of multistep reaction and expensive cofactor.

scholarly journals Expression of thermophilic two-domain laccase from Catenuloplanes japonicus in Escherichia coli and its activity against triarylmethane and azo dyes

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11646
Author(s):  
Liubov Igorevna Trubitsina ◽  
Azat Vadimovich Abdullatypov ◽  
Anna Petrovna Larionova ◽  
Ivan Vasilyevich Trubitsin ◽  
Sergey Valerievich Alferov ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Redox Potential ◽  
Azo Dyes ◽  
Metal Ion ◽  
Chemical Properties ◽  
Reaction Medium ◽  
Triphenylmethane Dyes ◽  
Visible Absorption ◽  
Wide Range ◽  
Alkaline Conditions

Background Two-domain laccases are copper-containing oxidases found in bacteria in the beginning of 2000ths. Two-domain laccases are known for their thermal stability, wide substrate specificity and, the most important of all, their resistance to so-called «strong inhibitors» of classical fungal laccases (azides, fluorides). Low redox potential was found to be specific for all the two-domain laccases, due to which these enzymes lost the researchers’ interest as potentially applicable for various biotechnological purposes, such as bioremediation. Searching, obtaining and studying the properties of novel two-domain laccases will help to obtain an enzyme with high redox-potential allowing its practical application. Methods A gene encoding two-domain laccase was identified in Catenuloplanes japonicus genome, cloned and expressed in an Echerichia coli strain. The protein was purified to homogeneity by immobilized metal ion affinity chromatography. Its molecular properties were studied using electrophoresis in native and denaturing conditions. Physico-chemical properties, kinetic characteristics, substrate specificity and decolorization ability of laccase towards triphenylmethane dyes were measured spectrophotometrically. Results A novel two-domain recombinant laccase CjSL appeared to be a multimer with a subunit molecular mass of 37 kDa. It oxidized a wide range of phenolic substrates (ferulic acid, caffeic acid, hydroquinone, catechol, etc.) at alkaline pH, while oxidizing of non phenolic substrates (K4[Fe(CN)6], ABTS) was optimal at acidic pH. The UV-visible absorption spectrum of the purified enzyme was specific for all two-domain laccases with peak of absorption at 600 nm and shoulder at 340 nm. The pH optima of CjSL for oxidation of ABTS and 2, 6-DMP substrates were 3.6 and 9.2 respectively. The temperature optimum was 70 °C. The enzyme was most stable in neutral-alkaline conditions. CjSL retained 53% activity after pre-incubation at 90 °C for 60 min. The enzyme retained 26% activity even after 60 min of boiling. The effects of NaF, NaN3, NaCl, EDTA and 1,10-phenanthroline on enzymatic activity were investigated. Only 1,10-phenanthroline reduced laccase activity under both acidic and alkaline conditions. Laccase was able to decolorize triphenylmethane dyes and azo-dyes. ABTS and syringaldehyde were effective mediators for decolorization. The efficacy of dye decolorization depended on pH of the reaction medium.

scholarly journals Effect of Sequences of the Active-Site Dipeptides of DsbA and DsbC on In Vivo Folding of Multidisulfide Proteins inEscherichia coli

2001 ◽  
Vol 183 (3) ◽  
pp. 980-988 ◽  
Author(s):  
Paul H. Bessette ◽  
Ji Qiu ◽  
James C. A. Bardwell ◽  
James R. Swartz ◽  
George Georgiou
Keyword(s):  
Redox Potential ◽  
Active Site ◽  
Active Sites ◽  
Multicopy Plasmid ◽  
Redox Potentials ◽  
Cxxc Motif ◽  
Wide Range ◽  
Significant Difference ◽  
Disulfide Isomerization

ABSTRACT We have examined the role of the active-site CXXC central dipeptides of DsbA and DsbC in disulfide bond formation and isomerization in the Escherichia coli periplasm. DsbA active-site mutants with a wide range of redox potentials were expressed either from the trc promoter on a multicopy plasmid or from the endogenous dsbA promoter by integration of the respective alleles into the bacterial chromosome. ThedsbA alleles gave significant differences in the yield of active murine urokinase, a protein containing 12 disulfides, including some that significantly enhanced urokinase expression over that allowed by wild-type DsbA. No direct correlation between the in vitro redox potential of dsbA variants and the urokinase yield was observed. These results suggest that the active-site CXXC motif of DsbA can play an important role in determining the folding of multidisulfide proteins, in a way that is independent from DsbA's redox potential. However, under aerobic conditions, there was no significant difference among the DsbA mutants with respect to phenotypes depending on the oxidation of proteins with few disulfide bonds. The effect of active-site mutations in the CXXC motif of DsbC on disulfide isomerization in vivo was also examined. A library of DsbC expression plasmids with the active-site dipeptide randomized was screened for mutants that have increased disulfide isomerization activity. A number of DsbC mutants that showed enhanced expression of a variant of human tissue plasminogen activator as well as mouse urokinase were obtained. These DsbC mutants overwhelmingly contained an aromatic residue at the C-terminal position of the dipeptide, whereas the N-terminal residue was more diverse. Collectively, these data indicate that the active sites of the soluble thiol- disulfide oxidoreductases can be modulated to enhance disulfide isomerization and protein folding in the bacterial periplasmic space.

Microgravity Separation of Alginate Empty Capsules from Encapsulated Pancreatic Islets Using a Microfluidic System

2015 ◽  
Vol 15 (10) ◽  
pp. 7876-7880 ◽  
Author(s):  
Soojeong Shin ◽  
Young Je Yoo ◽  
Jong Wook Hong
Keyword(s):  
Pancreatic Islets ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Biomedical Application ◽  
Gradient Centrifugation ◽  
Previous Method ◽  
High Yield ◽  
One Pot ◽  
Optimal Separation

Although microencapsulated pancreatic islets have merits, such as ease of transplantation, viability and functionality improvement, and immune protection in vivo, the co-production of alginate empty capsules during the encapsulation of islets with alginate makes them unusable for biomedical application. In previous research, the removal of empty alginate capsules with high yield was achieved using density-gradient centrifugation. Here, we report advanced microgravity-based separation techniques in a microfluidic format for alginate empty capsules. The optimal separation conditions were mathematically evaluated using Stokes’ law and the separation of the encapsulation product was accomplished. A microfluidic chip was designed with two inlets and two outlets at different elevations to mimic the vertical percoll gradient in density-gradient centrifugation. The separation of alginate empty capsules using microgravitational force resulted in effective separation of encapsulated islets from alginate empty capsules with more than 70% efficiency. Moreover, no loss of encapsulated islets was expected because the process is a one-pot separation, unlike the previous method. This type of microgravitational particle separation could be used both for the fractionization of heterogeneous encapsulated cells and to remove empty capsules.

scholarly journals Modular, ultra-stable, and highly parallel protein force spectroscopy in magnetic tweezers using peptide linkers

2018 ◽  
Author(s):  
Achim Löf ◽  
Philipp U Walker ◽  
Steffen M Sedlak ◽  
Tobias Obser ◽  
Maria A Brehm ◽  
...  
Keyword(s):  
Single Molecule ◽  
Force Spectroscopy ◽  
Magnetic Tweezers ◽  
Protein Domain ◽  
High Yield ◽  
Primary Hemostasis ◽  
Wide Range ◽  
And Function ◽  
Von Willebrand

Single-molecule force spectroscopy has provided unprecedented insights into protein folding, force-regulation, and function. Here, we present a modular magnetic tweezers force spectroscopy approach that uses elastin-like polypeptide linkers to provide a high yield of protein tethers. Our approach extends protein force spectroscopy into the low force (<1 pN) regime and enables ultra-stable measurements on many molecules in parallel. We present (un-)folding data for the single protein domain ddFLN4 and for the large multi-domain dimeric protein von Willebrand factor (VWF) that is critically involved in primary hemostasis. The measurements reveal exponential force-dependencies of unfolding and refolding rates, directly resolve the stabilization of the VWF A2 domain by Ca2+, and discover transitions in the VWF C-domain stem at low forces that likely constitute the first steps of VWF activation in vivo. Our modular attachment approach will enable precise and multiplexed force spectroscopy measurements for a wide range of proteins in the physiologically relevant force regime.

SLS-catalyzed Multi-component One-pot Reactions for the Convenient Synthesis of Spiro[indoline-3,4’-pyrano [2,3-c]pyrazole] Derivatives

2020 ◽  
Vol 07 ◽  
Author(s):  
Archana Dhakar ◽  
Archana Rajput ◽  
Ghazala Khanum ◽  
Dau D. Agarwal
Keyword(s):  
Anticancer Agents ◽  
Heterocyclic Compounds ◽  
Ethyl Cyanoacetate ◽  
Reaction Times ◽  
Thermal Conditions ◽  
Biological Properties ◽  
High Yield ◽  
Spectroscopic Techniques ◽  
One Pot ◽  
Wide Range

Background,Objective: : spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] derivatives are an important heterocyclic compounds. These compounds shows wide range of biological properties and exhibits varied pharmaceutical applications. Pyranopyrazoles, which are basically fused heterocyclic compounds and act as vasodilators, hypertensive, hypoglycaemic, and anticancer agents. Methods: An efficient and micelle-promoted surfactant catalyzed synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] derivatives have been achieved via one-pot four-component reaction of hydrazine hydrate (phenyl hydrazine), ethyl acetoacetate, malononitrile (ethyl cyanoacetate) and isatin under thermal conditions (at 60°C) in water as a solvent. Results: Sodium lauryl sulphate (SLS) used has been found to be an efficient and green catalyst. The compounds reported during this work were obtained in excellent yield, in a short duration of time and ease of work up. They were purified by recrystalization from ethanol, and also the synthesized compounds were characterized by various spectroscopic techniques. Conclusion: The method offers several advantages such as safe, cost-effective and catalyst easily recovered and reused for a minimum of five cycles, that confirms its good stability. Short reaction times, high yield and usage of eco-friendly catalyst and solvent are the key features of this methodology.

scholarly journals A Photo-Enzymatic Cascade to Transform Racemic Alcohols into Enantiomerically Pure Amines

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 305 ◽  
Author(s):  
Jenő Gacs ◽  
Wuyuan Zhang ◽  
Tanja Knaus ◽  
Francesco G. Mutti ◽  
Isabel W.C.E. Arends ◽  
...  
Keyword(s):  
Aromatic Compounds ◽  
Reductive Amination ◽  
Aerobic Oxidation ◽  
Secondary Alcohols ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Step Procedure ◽  
Wide Range ◽  
Aldehydes And Ketones ◽  
One Step

The consecutive photooxidation and reductive amination of various alcohols in a cascade reaction were realized by the combination of a photocatalyst and several enzymes. Whereas the photocatalyst (sodium anthraquinone-2-sulfonate) mediated the light-driven, aerobic oxidation of primary and secondary alcohols, the enzymes (various ω-transaminases) catalyzed the enantio-specific reductive amination of the intermediate aldehydes and ketones. The system worked in a one-pot one-step fashion, whereas the productivity was significantly improved by switching to a one-pot two-step procedure. A wide range of aliphatic and aromatic compounds was transformed into the enantiomerically pure corresponding amines via the photo-enzymatic cascade.

scholarly journals Enantiomeric glycosylated cationic block co-beta-peptides eradicate Staphylococcus aureus biofilms and antibiotic-tolerant persisters

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Kaixi Zhang ◽  
Yu Du ◽  
Zhangyong Si ◽  
Yang Liu ◽  
Michelle E. Turvey ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bacterial Infections ◽  
Ex Vivo ◽  
High Yield ◽  
Bacterial Cells ◽  
One Pot ◽  
Beta Peptide ◽  
Repeated Dosing ◽  
Multiple Drugs

Abstract The treatment of bacterial infections is hindered by the presence of biofilms and metabolically inactive persisters. Here, we report the synthesis of an enantiomeric block co-beta-peptide, poly(amido-D-glucose)-block-poly(beta-L-lysine), with high yield and purity by one-shot one-pot anionic-ring opening (co)polymerization. The co-beta-peptide is bactericidal against methicillin-resistant Staphylococcus aureus (MRSA), including replicating, biofilm and persister bacterial cells, and also disperses biofilm biomass. It is active towards community-acquired and hospital-associated MRSA strains which are resistant to multiple drugs including vancomycin and daptomycin. Its antibacterial activity is superior to that of vancomycin in MRSA mouse and human ex vivo skin infection models, with no acute in vivo toxicity in repeated dosing in mice at above therapeutic levels. The copolymer displays bacteria-activated surfactant-like properties, resulting from contact with the bacterial envelope. Our results indicate that this class of non-toxic molecule, effective against different bacterial sub-populations, has promising potential for the treatment of S. aureus infections.

Preparation of chiral 1-phenylethanols and bromides

1985 ◽  
Vol 63 (12) ◽  
pp. 3442-3448 ◽  
Author(s):  
Allan R. Stein ◽  
Robert D. Dawe ◽  
James R. Sweet
Keyword(s):  
General Procedure ◽  
Optical Purity ◽  
Secondary Alcohols ◽  
One Pot ◽  
Convenient Procedure ◽  
Optical Rotations ◽  
Nmr Methods ◽  
Substituted 1

A fast, convenient procedure for preparing and resolving moderate to large quantities of chiral secondary alcohols is described. The general procedure involves a one-pot conversion of the ketone (various acetophenones) to the half-ester of a diacid (succinic, phthalic… ) and resolution with (+)- and (−)-1-phenylethylamines. Overall yields of the enantiomeric alcohols, the variously substituted 1-phenylethanols, are generally 65–85% with optical purities of approximately 90%. Properties and optical rotations of a number of chiral 1-phenylethanols and of the bromides made from them are tabulated. A discussion of optical purity determinations using nmr methods is included and absolute configurations are reported.

Arsonoliposomes: Novel Nanosized Arsenic-Containing Vesicles for Drug Delivery

2006 ◽  
Vol 6 (9) ◽  
pp. 2618-2637 ◽  
Author(s):  
Dimitris G. Fatouros ◽  
Panayiotis V. Ioannou ◽  
Sophia G. Antimisiaris
Keyword(s):  
Arsenic Trioxide ◽  
Membrane Integrity ◽  
Biochemical Properties ◽  
High Yield ◽  
One Pot ◽  
Antiparasitic Activity ◽  
Therapeutic Applications ◽  
Induced Aggregation

Natural and synthetic arsenolipids, have been discovered, synthesized, and evaluated for their biological activity. Arsonolipids, are analogs of phosphonolipids, in which P has been replaced by As. The synthesis of arsonolipids has been explored and a simple one-pot method with high yield is currently available for their preparation. However, although arsonolipids posses interesting biophysical and biochemical properties their anticancer or antiparasitic activity is not considered adequate for therapeutic applications. But when arsonolipids are incorporated in liposomes, the vesicles formulated have interesting possibilities, as seen in a number of studies. In cell culture studies, nanosized arsonolipid-containing liposomes or else arsonoliposomes, showed increased toxicity against cancer cells (compared to that of arsenic trioxide) but at the same time were less toxic than arsenic trioxide for normal cells. Furthermore, arsonoliposomes also demonstrate antiparasitic activity in vitro. Nevertheless, As is rapidly cleared from blood after in vivo administration of arsonoliposomes, and this will highly limit possible therapeutic applications. In addition, the fact that arsonoliposomes were observed to aggregate and subsequently fuse into larger particles in presence of cations, may also be considered as a problem. Thereby, methods to modulate the stability of arsonoliposomes and, perhaps, their in vivo distribution (as surface property modification) are currently being investigated. In very recent experiments it has been shown that arsonoliposome pegylation results in the formation of liposomes with very high membrane integrity. In addition, pegylation results in increased physical stability of arsonoliposomes and abolishment of cation-induced aggregation and fusion. Nevertheless, further in vivo studies are required in order to prove if pegylation alters arsonoliposome in vivo kinetics in a positive way, without affecting their activity. From studies performed thus far it is concluded that arsonoliposomes are nanosized-vesicles with interesting properties that justify further exploitation towards the development of therapeutic systems for cancer or parasitic diseases.

One-pot Synthesis of 2-Chloro-2-thio/selenocyanato Ketones from β-Keto Acids

2021 ◽  
Author(s):  
Di Wu ◽  
Chengcheng Li ◽  
Yong Jie Duan ◽  
Hongquan Yin ◽  
Fu-Xue Chen
Keyword(s):  
High Yield ◽  
One Pot ◽  
One Pot Synthesis ◽  
Keto Acids ◽  
Wide Range

The chlorothiocyanato difunctionalization reactions has been achieved to synthesis α-chlorothio/selenocyanato ketones, a variety of α-chlorothio/selenocyanato difunctional ketones is synthesized through one-pot strategy from β-ketone acids. The high yield and wide-range...

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