scholarly journals Biophysical characterization of the inactivation of E. coli transketolase by aqueous co-solvents

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Phattaraporn Morris ◽  
Ribia García-Arrazola ◽  
Leonardo Rios-Solis ◽  
Paul A. Dalby
Keyword(s):  
Water Solubility ◽  
Conformational Stability ◽  
Enzyme Inactivation ◽  
Solvent Tolerance ◽  
Log P ◽  
Biophysical Characterization ◽  
E Coli ◽  
Cofactor Binding ◽  
Local Unfolding ◽  
The Stability

AbstractTransketolase (TK) has been previously engineered, using semi-rational directed evolution and substrate walking, to accept increasingly aliphatic, cyclic, and then aromatic substrates. This has ultimately led to the poor water solubility of new substrates, as a potential bottleneck to further exploitation of this enzyme in biocatalysis. Here we used a range of biophysical studies to characterise the response of both E. coli apo- and holo-TK activity and structure to a range of polar organic co-solvents: acetonitrile (AcCN), n-butanol (nBuOH), ethyl acetate (EtOAc), isopropanol (iPrOH), and tetrahydrofuran (THF). The mechanism of enzyme deactivation was found to be predominantly via solvent-induced local unfolding. Holo-TK is thermodynamically more stable than apo-TK and yet for four of the five co-solvents it retained less activity than apo-TK after exposure to organic solvents, indicating that solvent tolerance was not simply correlated to global conformational stability. The co-solvent concentrations required for complete enzyme inactivation was inversely proportional to co-solvent log(P), while the unfolding rate was directly proportional, indicating that the solvents interact with and partially unfold the enzyme through hydrophobic contacts. Small amounts of aggregate formed in some cases, but this was not sufficient to explain the enzyme inactivation. TK was found to be tolerant to 15% (v/v) iPrOH, 10% (v/v) AcCN, or 6% (v/v) nBuOH over 3 h. This work indicates that future attempts to engineer the enzyme to better tolerate co-solvents should focus on increasing the stability of the protein to local unfolding, particularly in and around the cofactor-binding loops.

scholarly journals Biophysical characterization of the inactivation of E. coli transketolase by aqueous co-solvents

2020 ◽  
Author(s):  
Phattaraporn Morris ◽  
Ribia García-Arrazola ◽  
Leonardo Rios-Solis ◽  
Paul A. Dalby
Keyword(s):  
Water Solubility ◽  
Conformational Stability ◽  
Enzyme Inactivation ◽  
Solvent Tolerance ◽  
Log P ◽  
Driving Mechanism ◽  
Biophysical Characterization ◽  
E Coli ◽  
Local Unfolding ◽  
The Stability

AbstractTransketolase (TK) has been previously engineered, using semi-rational directed evolution and substrate walking, to accept increasingly aliphatic, cyclic and then aromatic substrates. This has ultimately led to the poor water solubility of new substrates, as a potential bottleneck to further exploitation of this enzyme in biocatalysis. Here we used a range of biophysical studies to characterise the response of both E. coli apo- and holo-TK activity and structure to a range of commonly used polar organic co-solvents: acetonitrile (MeCN), n- butanol (nBuOH), ethyl acetate (EToAc), isopropanol (iPrOH), and tetrahydrofuran (THF). The mechanism of enzyme deactivation was found to be predominantly via solvent-induced local unfolding. Holo-TK is thermodynamically more stable than apo-TK and yet for four of the five co-solvents it retained less activity than apo-TK after exposure to organic solvents, indicating that solvent tolerance was not correlated to global conformational stability. The co-solvent concentrations required for complete enzyme inactivation was inversely proportional to co-solvent log(P), while the unfolding rate was directly proportional, indicating that the solvents interact with and partially unfold the enzyme through hydrophobic contacts. Aggregation was not found to be the driving mechanism of enzyme inactivation, but was in some cases an additional impact of solvent-induced local or global unfolding.TK was found to be tolerant to 15% (v/v) iPrOH, 10% (v/v) MeCN, or 6% (v/v) nBuOH over 3 hours. This work indicates that future attempts to engineer the enzyme to better tolerate co-solvents should focus on increasing the stability of the protein to local unfolding, particularly in and around the cofactor-binding loops.

Quantitative Structure-Property Relationship (QSPR) Study of the Hydrophobicity of Phenols and 2-(Aryloxy-a-acetyl)-phenoxathiin Derivatives

2008 ◽  
Vol 59 (11) ◽  
Author(s):  
Adrian Beteringhe ◽  
Ana Cristina Radutiu ◽  
Titus Constantinescu ◽  
Luminita Patron ◽  
Alexandru T. Balaban
Keyword(s):  
Water Solubility ◽  
Molecular Descriptors ◽  
Log P ◽  
Structure Property ◽  
Substituted Phenols ◽  
Reverse Phase ◽  
Aromaticity Index ◽  
Structure Property Relationship ◽  
Layer Chromatography ◽  
Energy Of Formation

In a preceding study, the molecular hydrophobicity (RM0) was determined experimentally from reverse-phase thin-layer chromatography data for several substituted phenols and 2-(aryloxy-a-acetyl)-phenoxathiin derivatives, obtained from the corresponding phenoxides and 2-(a-bromoacetyl)-phenoxathiin. QSPR correlations for RM0 were explored using four calculated molecular descriptors: the water solubility parameter (log Sw), log P, the Gibbs energy of formation (DGf), and the aromaticity index (HOMA). Triparametric correlations do not improve substantially the biparametric correlation of RM0 in terms of log Sw and HOMA.

scholarly journals Life without Division: Physiology ofEscherichia coliFtsZ-Deprived Filaments

mBio ◽  
2016 ◽  
Vol 7 (5) ◽  
Author(s):  
Alicia Sánchez-Gorostiaga ◽  
Pilar Palacios ◽  
Rocío Martínez-Arteaga ◽  
Manuel Sánchez ◽  
Mercedes Casanova ◽  
...  
Keyword(s):  
Solid Medium ◽  
Membrane Integrity ◽  
Test Tube ◽  
Antimicrobial Compounds ◽  
Liquid Form ◽  
Altered Expression ◽  
E Coli ◽  
Ftsz Ring ◽  
Altered Expression Pattern ◽  
The Stability

ABSTRACTWhen deprived of FtsZ,Escherichia colicells (VIP205) grown in liquid form long nonseptated filaments due to their inability to assemble an FtsZ ring and their failure to recruit subsequent divisome components. These filaments fail to produce colonies on solid medium, in which synthesis of FtsZ is induced, upon being diluted by a factor greater than 4. However, once the initial FtsZ levels are recovered in liquid culture, they resume division, and their plating efficiency returns to normal. The potential septation sites generated in the FtsZ-deprived filaments are not annihilated, and once sufficient FtsZ is accumulated, they all become active and divide to produce cells of normal length. FtsZ-deprived cells accumulate defects in their physiology, including an abnormally high number of unsegregated nucleoids that may result from the misplacement of FtsK. Their membrane integrity becomes compromised and the amount of membrane proteins, such as FtsK and ZipA, increases. FtsZ-deprived cells also show an altered expression pattern, namely, transcription of several genes responding to DNA damage increases, whereas transcription of some ribosomal or global transcriptional regulators decreases. We propose that the changes caused by the depletion of FtsZ, besides stopping division, weaken the cell, diminishing its resiliency to minor challenges, such as dilution stress.IMPORTANCEOur results suggest a role for FtsZ, in addition to its already known effect in the constriction ofE. coli, in protecting the nondividing cells against minor stress. This protection can even be exerted when an inactive FtsZ is produced, but it is lost when the protein is altogether absent. These results have implications in fields like synthetic biology or antimicrobial discovery. The construction of synthetic divisomes in the test tube may need to preserve unsuspected roles, such as this newly found FtsZ property, to guarantee the stability of artificial containers. Whereas the effects on viability caused by inhibiting the activity of FtsZ may be partly overcome by filamentation, the absence of FtsZ is not tolerated byE. coli, an observation that may help in the design of effective antimicrobial compounds.

scholarly journals Estimation of the retention behaviour of s-triazine derivatives applying multiple regression analysis of selected molecular descriptors

2013 ◽  
pp. 229-237 ◽  
Author(s):  
Lidija Jevric ◽  
Sanja Podunavac-Kuzmanovic ◽  
Strahinja Kovacevic ◽  
Natasa Kalajdzija ◽  
Bratislav Jovanovic
Keyword(s):  
Dissociation Constant ◽  
Water Solubility ◽  
Molecular Descriptors ◽  
Chemical Properties ◽  
Log P ◽  
Retention Factors ◽  
Solute Retention ◽  
Physico Chemical ◽  
Hydrophilic Lipophilic Balance ◽  
Triazine Derivatives

The estimation of retention factors by correlation equations with physico-chemical properties can be of great helpl in chromatographic studies. The retention factors were experimentally measured by RP-HPTLC on impregnated silica gel with paraffin oil using two-component solvent systems. The relationships between solute retention and modifier concentration were described by Snyder?s linear equation. A quantitative structure-retention relationship was developed for a series of s-triazine compounds by the multiple linear regression (MLR) analysis. The MLR procedure was used to model the relationships between the molecular descriptors and retention of s-triazine derivatives. The physicochemical molecular descriptors were calculated from the optimized structures. The physico-chemical properties were the lipophilicity (log P), connectivity indices (?), total energy (Et), water solubility (log W), dissociation constant (pKa), molar refractivity (MR), and Gibbs energy (GibbsE) of s-triazines. A high agreement between the experimental and predicted retention parameters was obtained when the dissociation constant and the hydrophilic-lipophilic balance were used as the molecular descriptors. The empirical equations may be successfully used for the prediction of the various chromatographic characteristics of substances, with a similar chemical structure.

scholarly journals Bactericidal and virucidal efficacies of food additive grade calcium hydroxide under various concentrations, organic material conditions, exposure duration, and its stability

2019 ◽  
Vol 12 (9) ◽  
pp. 1383-1389
Author(s):  
Sakchai Ruenphet ◽  
Kornkamon Paditporn ◽  
Darsaniya Punyadarsaniya ◽  
Tippawan Jantafong ◽  
Kazuaki Takehara
Keyword(s):  
Calcium Hydroxide ◽  
Organic Material ◽  
Exposure Duration ◽  
Organic Materials ◽  
Exposure Period ◽  
Food Additive ◽  
E Coli ◽  
Dry Conditions ◽  
Material Conditions ◽  
The Stability

Aim: This study aimed to evaluate the bactericidal and virucidal activity of food additive grade calcium hydroxide (FdCa(OH)2) under various concentrations, organic material conditions, and exposure duration including its stability. Materials and Methods: The FdCa(OH)2 powder as well as the 0.17% and 3% solutions were evaluated for bacteria and virus inactivating efficacies against Salmonella infantis (SI), Escherichia coli, Newcastle disease virus (NDV), and avian influenza virus (AIV), in the absence or presence of organic materials. In addition, the stability of FdCa(OH)2, was also examined using wet-dry conditions and under sunlight. Results: The FdCa(OH)2 powder could inactivate both NDV and AIV in the absence and presence of organic materials within a 3 min exposure period. The bactericidal efficacy using solution form revealed that 0.17% and 3% of FdCa(OH)2 could inactivate SI in the absence and presence of organic materials within 3 min of exposure. However, 3% of FdCa(OH)2 inactivated E. coli both with and without organic materials within 3min, while 0.17% required 5 min to be efficacious. The virucidal efficacy also showed that 0.17% FdCa(OH)2 could inactivate NDV in the absence and presence of organic materials within 10 min and 30 min, respectively. However, AIV inactivation was achieved within 30 sec under all conditions. In addition, under wet and dry conditions, FdCa(OH)2 powder demonstrated high efficacy when re-suspended at least 16 times for NDV and 7 times for AIV. Simultaneously, the FdCa(OH)2 powder retained its efficacy under the sunlight during up to 4 months for NDV and at least 6 months for AIV. Conclusion: The present study indicates that FdCa(OH)2 powder and solutions could inactivate SI, E. coli, NDV, and AIV while retaining good stability under challenging environmental conditions. Finally, the FdCa(OH)2 is safe for consumers because it is of food additive grade and can be useful as an alternative disinfectant, especially for biosecurity enhancement on and around poultry farms.

scholarly journals A study of the effects of sodium alginate and sodium carboxymethyl cellulose on the growth of the common duckweed (Lemna minor L.)

2021 ◽  
pp. 82-82
Author(s):  
Bianca Boros ◽  
Nathalie Grau ◽  
Adriana Isvoran ◽  
Adina Datcu ◽  
Nicoleta Ianovici ◽  
...  
Keyword(s):  
Sodium Alginate ◽  
Carboxymethyl Cellulose ◽  
Water Solubility ◽  
Lemna Minor ◽  
Sodium Carboxymethyl Cellulose ◽  
Log P ◽  
Growth Inhibitory ◽  
Wide Range ◽  
The Common ◽  
High Doses

Sodium alginate (ALG) and sodium carboxymethyl cellulose (CMC) are two polysaccharides that have a wide range of applications which could lead to accidental pollution of the environment, making the assessment of their potential ecotoxicity imperative. The present study assesses the ALG and CMC effects on the growth response of the common duckweed (Lemna minor L.). The results emphasize that both polysaccharides can be classified as practically nontoxic based on their EC50 values, with ALG having a relatively higher toxicity compared to CMC. It was also observed that high doses of 1, 5 and 10 mg mL-1 of the two polysaccharides produced growth inhibitory effects against common duckweed. The toxicity of biopolymers against common duckweed, measured as EC50 values, seems to be correlated to the hydrophobicity of the monomers building the polymer. The EC50 values increase linearly with the increase of water solubility (log S) values and decrease linearly with the lipophilicity (log P) values.

scholarly journals Encapsulation Systems for Delivery of Flavonoids: A Review

2021 ◽  
Vol 11 (6) ◽  
pp. 13934-13951
Keyword(s):  
Fruits And Vegetables ◽  
Water Solubility ◽  
Biological Activities ◽  
Molecular Complexes ◽  
Multilamellar Vesicles ◽  
Promising Tool ◽  
Inflammatory Bowel ◽  
The Stability ◽  
Encapsulation Methods ◽  
As Solubility

Encapsulation of bioactive compounds s been considered a promising tool for preserving these compounds. Several studies on dietary sources and health benefits of flavonoids, their chemical and stability properties, and encapsulation methods used for delivery of flavonoids were reviewed. Flavonoids comprise the main group of polyphenols widely found in fruits and vegetables responsible for numerous biological activities. They have a flavan nucleus with 15 carbon atoms organized in three rings and are categorized into six subgroups. The main dietary sources of flavonoids are fruits, vegetables, cereals, tea, and some herbs such as Viola odorata Linn. These compounds can prevent diseases such as cardiovascular, cancers, neurodegenerative, diabetes, and inflammatory bowel disease. Despite these beneficial biological activities, flavonoids are not stable against environmental conditions, have low water solubility and low bioavailability after oral administration, which restricts their application. Accordingly, encapsulation has been utilized in order to improve the stability and solubility of flavonoids. Various approaches such as spray drying, molecular complexes, liposomes, nanoparticles, emulsification, and multilamellar vesicles have been applied in the entrapment of flavonoids. Encapsulation can improve the stability of flavonoids as well as solubility, controlled release, and bioavailability.

scholarly journals In Vitro and In Vivo Assessment of the Potential of Escherichia coli Phages to Treat Infections and Survive Gastric Conditions

2021 ◽  
Vol 9 (9) ◽  
pp. 1869
Author(s):  
Joanna Kaczorowska ◽  
Eoghan Casey ◽  
Gabriele A. Lugli ◽  
Marco Ventura ◽  
David J. Clarke ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Galleria Mellonella ◽  
Enterotoxigenic Escherichia Coli ◽  
E Coli ◽  
Composite Mixture ◽  
Ph Conditions ◽  
The Stability ◽  
Higher Sensitivity

Enterotoxigenic Escherichia coli (ETEC) and Shigella ssp. infections are associated with high rates of mortality, especially in infants in developing countries. Due to increasing levels of global antibiotic resistance exhibited by many pathogenic organisms, alternative strategies to combat such infections are urgently required. In this study, we evaluated the stability of five coliphages (four Myoviridae and one Siphoviridae phage) over a range of pH conditions and in simulated gastric conditions. The Myoviridae phages were stable across the range of pH 2 to 7, while the Siphoviridae phage, JK16, exhibited higher sensitivity to low pH. A composite mixture of these five phages was tested in vivo in a Galleria mellonella model. The obtained data clearly shows potential in treating E. coli infections prophylactically.

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