Interactions Mode of Amphoteric Molecules with Ordered Phospholipid Membrane

Aim To explore interaction mode between amphoteric molecules with the orderedphospholipid membrane. Methods Membrane interactions were determined by immobilized artificialmembrane (IAM) chromatography and solutes' hydrophobicity was measured by n-octanol/buffer system.Results The ampholytes, similar to bases, generally exhibited higher membrane affinity than expectedfrom their hydrophobicity, resulting from the attractive polar interaction with phospholipidmembrane. Furthermore, the strength of additional polar interaction with membrane (Δlg k_(IAM)) wasthen calculated. The Δlg k_(IAM) values were far greater for bases and ampholytes ranging from0.50 - 1.39, than those for acids and neutrals with the scope from - 0.55 - 0.44. ConclusionConsidering the microspecies distribution of amphoteric molecules, it was assumed that not onlyneutral and positive but also zwitterionic microspecies are capable of partitioning into orderedamphoteric lipid membrane with complementarily conformational and energetically favorableinteractions.

Acid-base and lipophilic properties of peptide nucleic acid derivatives

The first combined experimental and theoretical study on the ionization and lipophilic properties of peptide nucleic acid(PNA)derivatives,including eleven PNA monomers and two PNA decamers,is described.The acidity constants(pKa)of individual acidic and basic centers of PNA monomers were measured by automated potentiometric pH titrations in water/methanol solution,and these values were found to be in agreement with those obtained by MoKa software.These results indicate that single nucleobases do not change their pKa values when included in PNA monomers and oligomers.In addition,immobilized artificial membrane chromatography was employed to evaluate the lipophilic properties of PNA monomers and oligomers,which showed the PNA derivatives had poor affinity towards membrane phospholipids,and confirmed their scarce cell penetrating ability.Overall,our study not only is of potential relevance to evaluate the pharmacokinetic properties of PNA,but also constitutes a reliable basis to properly modify PNA to obtain mimics with enhanced cell penetration properties.

Preliminary study of groundwater denitrification using a composite membrane bioreactor

A composite membrane bioreactor(CMBR)integrating the immobilized cell technique and the membrane separation technology was developed for groundwater denitrification.The CMBR had two well mixed compartments with one filled with the nitratecontaining influent and the other with a dilute ethanol solution;the compartments were separated by the composite membrane consisting of a microporous membrane facing the influent and an immobilized cell membrane facing the ethanol solution.Nitrate and ethanol molecules diffused from the respective compartments into the immobilized cell membrane where nitrate was reduced to gaseous nitrogen by the denitrifying bacteria present there with ethanol as the carbon source.The microporous membrane was attached to one side of the immobilized cell membrane for retention of the disaggregated bacteria.Relative to the single dose of external ethanol,the twodose supplementation produced better treatment results as evidenced by the lower concentrations of NO_(3)^(-)-N and ethanol(as measured by total organic carbon)of the effluent.The batch treatment in CMBR removed most of the nitrate in the influent and attained a stable denitrification rate of 0.1 g·m^(-2)·h^(-1)for most of the 96-h cycles during the 30-cycle study.The effluent was essentially free of ethanol and nitrite nitrogen.

A review of microbial laccase production and activity toward different biotechnological applications

Laccases are versatile enzymes that belong to the multi-copper oxidase family.This enzyme has several biotechnological applications because of its ablilty to oxidize a wide range of phenolic and non-phenolic substrates.However,their large-scale applicability in bioremediation and water treatment is hindered by high salt content and extreme pH values of the polluted media which also affects the stability,recovery and recycling of laccase.Apart from some bacteria,laccase is abundantly present in several lignin-degrading white-rot fungi viz.Ascomycetes,Deuteromycetes,and Basidiomycetes.Recently,lac-case has been employed in the development of biosensors as a medical diagnostic tool,biofuel cells,and in bioremediation purpose to remove herbicides,pesticides,and some toxic chemicals from the soil.However,most of the enzymes including laccase are normally unstable and susceptible to lose their activity over time.This might be avoided by maintaining the activity and lengthening the enzyme's lifespan through the use of appropriate immobilization procedures.The potential of laccase immobilized biocathodes for dye decolorization in microbial fuel cells has recently been studied.Immobilized laccase nanoparticles have potential uses as biocatalyst in the bioremediation of pollutants.In addition,advanced research considering microbial laccase has been conducted for its heterologous expression along with in silico protein engineering to attain maximum enzyme activity which can be potentially applied in different biotechnological sectors.Patent related to laccase also implied that this enzyme can be used as suitable catalyst for the production of promising anti-cancer drugs and even as a significant ingredient in cosmetics.