Preparation and Characterization of Doxycycline-Loaded Electrospun PLA/HAP Nanofibers as a Drug Delivery System.

The present study aimed to prepare nanofibers by electrospinning in the system polylactic acid-hydroxyapatite-doxycycline (PLA-HAP-Doxy) to be used as a drug delivery vehicle. Two different routes were employed for the preparation of Doxy-containing nanofibers: Immobilization on the electrospun mat's surface and encapsulation in the fiber structure. The nanofibers obtained by Doxy encapsulation were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) and differential thermal analyses (DTA) and scanning electron microscopy (SEM).

Robust, site-specifically immobilized phenylalanine ammonia-lyases for the enantioselective ammonia addition of cinnamic acids.

Phenylalanine ammonia-lyases (PALs) catalyse the non-oxidative deamination of l-phenylalanine to -cinnamic acid, while in the presence of high ammonia concentration, the synthetically attractive reverse reaction occurs. Although they have been intensively studied, the wider application of PALs for the large scale synthesis of non-natural amino acids is still rather limited, mainly due to the decreased operational stability of PALs under the high ammonia concentration conditions of ammonia addition. Herein, we describe the development of a highly stable and active immobilized PAL-biocatalyst obtained through site-specific covalent immobilization onto single-walled carbon nanotubes (SWCNTs), employing maleimide/thiol coupling of engineered enzymes containing surficial Cys residues.

Fluorescent enzyme-coupled activity assay for phenylalanine ammonia-lyases.

Phenylalanine ammonia-lyases (PALs) catalyse the non-oxidative deamination of L-phenylalanine to trans-cinnamic acid, while in the presence of high ammonia concentration the reverse reaction occurs. PALs have been intensively studied, however, their industrial applications for amino acids synthesis remained limited, mainly due to their decreased operational stability or limited substrate specificity. The application of extensive directed evolution procedures to improve their stability, activity or selectivity, is hindered by the lack of reliable activity assays allowing facile screening of PAL-activity within large-sized mutant libraries.

Efficient Biodiesel Production Catalyzed by Nanobioconjugate of Lipase from .

The Amano lipase from (L-AK) was covalently immobilized on various carbon nanomaterials (functionalized single-walled carbon nanotubes and graphene oxide) and tested for biodiesel production. Using the most active lipase preparation (covalently immobilized L-AK on SwCNT derivatized with glycerol diglycidyl ether) under optimal conditions, quasi-complete conversion (>99%) of sunflower oil was obtained after only 4 h reaction time. Moreover, the biocatalyst maintained more than 99% of its initial activity in the batch system after multiple recycling experiments.

Efficient and Stable Magnetic Chitosan-Lipase B from Bioconjugates in the Enzymatic Kinetic Resolution of Racemic Heteroarylethanols.

Lipase B from immobilized by covalent binding on sebacoyl-activated chitosan-coated magnetic nanoparticles proved to be an efficient biocatalyst (49.2-50% conversion in 3-16 h and >96% enantiomeric excess) for the enzymatic kinetic resolution of some racemic heteroarylethanols through transesterification with vinyl acetate. Under optimal conditions (vinyl acetate, -hexane, 45 °C), the biocatalyst remains active after 10 cycles.

The production of L- and D-phenylalanines using engineered phenylalanine ammonia lyases from Petroselinum crispum.

The biocatalytic synthesis of L- and D-phenylalanine analogues of high synthetic value have been developed using as biocatalysts mutant variants of phenylalanine ammonia lyase from Petroselinum crispum (PcPAL), specifically tailored towards mono-substituted phenylalanine and cinnamic acid substrates. The catalytic performance of the engineered PcPAL variants was optimized within the ammonia elimination and ammonia addition reactions, focusing on the effect of substrate concentration, biocatalyst:substrate ratio, reaction buffer and reaction time, on the conversion and enantiomeric excess values. The optimal conditions provided an efficient preparative scale biocatalytic procedure of valuable phenylalanines, such as (S)-m-methoxyphenylalanine (Y = 40%, ee > 99%), (S)-p-bromophenylalanine (Y = 82%, ee > 99%), (S)-m-(trifluoromethyl)phenylalanine (Y = 26%, ee > 99%), (R)-p-methylphenylalanine, (Y = 49%, ee = 95%) and (R)-m-(trifluoromethyl)phenylalanine (Y = 34%, ee = 93%).

Simultaneous enrichment of grape pomace with γ-linolenic acid and carotenoids by solid-state fermentation with Zygomycetes fungi and antioxidant potential of the bioprocessed substrates.

Two filamentous fungi (Actinomucor elegans and Umbelopsis isabellina), were tested for their ability to enrich white grape pomace simultaneously with both γ-linolenic acid (GLA) and carotenoids through solid-state fermentation (SSF) processes. U. isabellina presented higher ability to produce GLA-rich lipids (composed mainly of neutral fractions) than A.

Tailored Mutants of Phenylalanine Ammonia-Lyase from for the Synthesis of Bulky l- and d-Arylalanines.

Tailored mutants of phenylalanine ammonia-lyase from (PAL) were created and tested in ammonia elimination from various sterically demanding, non-natural analogues of phenylalanine and in ammonia addition reactions into the corresponding ()-arylacrylates. The wild-type PAL was inert or exhibited quite poor conversions in both reactions with all members of the substrate panel. Appropriate single mutations of residue F137 and the highly conserved residue I460 resulted in PAL variants that were active in ammonia elimination but still had a poor activity in ammonia addition onto bulky substrates.

Modern diversification of the amino acid repertoire driven by oxygen.

All extant life employs the same 20 amino acids for protein biosynthesis. Studies on the number of amino acids necessary to produce a foldable and catalytically active polypeptide have shown that a basis set of 7-13 amino acids is sufficient to build major structural elements of modern proteins. Hence, the reasons for the evolutionary selection of the current 20 amino acids out of a much larger available pool have remained elusive.

Expanding the substrate scope of phenylalanine ammonia-lyase from Petroselinum crispum towards styrylalanines.

This study focuses on the expansion of the substrate scope of phenylalanine ammonia-lyase from Petroselinum crispum (PcPAL) towards the l-enantiomers of racemic styrylalanines rac-1a-d - which are less studied and synthetically challenging unnatural amino acids - by reshaping the aromatic binding pocket of the active site of PcPAL by point mutations. Ammonia elimination from l-styrylalanine (l-1a) catalyzed by non-mutated PcPAL (wt-PcPAL) took place with a 777-fold lower k/K value than the deamination of the natural substrate, l-Phe. Computer modeling of the reactions catalyzed by wt-PcPAL indicated an unproductive and two major catalytically active conformations and detrimental interactions between the aromatic moiety of l-styrylalanine, l-1a, and the phenyl ring of the residue F137 in the aromatic binding region of the active site.

Immobilization of Phenylalanine Ammonia-Lyase on Single-Walled Carbon Nanotubes for Stereoselective Biotransformations in Batch and Continuous-Flow Modes.

Carboxylated single-walled carbon nanotubes (SwCNT) were used as a support for the covalent immobilization of phenylalanine ammonia-lyase (PAL) from parsley by two different methods. The nanostructured biocatalysts (SwCNT-PAL and SwCNT-PAL) with low diffusional limitation were tested in the batch-mode kinetic resolution of racemic 2-amino-3-(thiophen-2-yl)propanoic acid () to yield a mixture of ()- and ()-3-(thiophen-2-yl)acrylic acid () and in ammonia addition to to yield enantiopure ()-. SwCNT-PAL was a stable biocatalyst (>90 % of the original activity remained after six cycles with and after three cycles in 6 m NH with ).

Heterocycles 36. Single-Walled Carbon Nanotubes-Bound N,N-Diethyl Ethanolamine as Mild and Efficient Racemisation Agent in the Enzymatic DKR of 2-Arylthiazol-4-yl-alanines.

In this paper we describe the chemoenzymatic synthesis of enantiopure l-2-arylthiazol-4-yl alanines starting from their racemic N-acetyl derivatives; by combining the lipase-catalysed dynamic kinetic resolution of oxazol-5(4H)-ones with a chemical and an enzymatic enantioselective hydrolytic step affording the desired products in good yields (74%-78%) and high enantiopurities (ee > 99%). The developed procedure exploits the utility of the single-walled carbon nanotubes-bound diethylaminoethanol as mild and efficient racemisation agent for the dynamic kinetic resolution of the corresponding oxazolones.

Nanobioconjugates of Candida antarctica lipase B and single-walled carbon nanotubes in biodiesel production.

Carboxylated single-walled carbon nanotubes (SWCNTCOOH) were used as support for covalent immobilization of Candida antarctica lipase B (CaL-B) using linkers with different lengths. The obtained nanostructured biocatalysts with low diffusional limitation were tested in batch mode in the ethanolysis of the sunflower oil. SWCNTCOOH-CaL-B proved to be a highly efficient and stable biocatalyst in acetonitrile (83.

Total phenolic contents, antioxidant activities, and lipid fractions from berry pomaces obtained by solid-state fermentation of two Sambucus species with Aspergillus niger.

The aim of this study was to investigate the effect of solid-state fermentation (SSF) by Aspergillus niger on phenolic contents and antioxidant activity in Sambucus nigra L. and Sambucus ebulus L. berry pomaces.

Molecular cloning and characterization of a thermostable esterase/lipase produced by a novel Anoxybacillus flavithermus strain.

A thermophilic strain producing an extracellular esterase/lipase was isolated from a hot spring in Tăşnad, Romania, and was identified phenotypically and by 16S rDNA sequencing as Anoxybacillus flavithermus (GenBank ID: JQ267733). The gene encoding the putative carboxyl esterase (GenBank ID: JX494348) was cloned by direct PCR amplification from genomic DNA. The protein, consisting of 246 amino acids and having a predicted molecular weight of 28.

Formyl- and acetylindols: vibrational spectroscopy of an expectably pharmacologically active compound family.

In the present paper, indole and its seven derivatives were compared, namely 3-formylindole, 1-methyl-3-formylindole, 1-ethyl-3-formylindole, 3-acetylindole, 1-methyl-3-acetylindole, 1-ethyl-3-acetylindole and 1,3-diacetylindole. The substitution of indole in position 3 with aldehydes and with alkyl groups cause only minor changes in the molecular geometry, however, substantially larger alterations are found in the charge distribution and in the vibrational force constants. The appearance of the aldehyde groups increased the degree of association as it was observable on the shape of infrared NH stretching band and its shifts.

Inhibition of histidine ammonia lyase by heteroaryl-alanines and acrylates.

Histidine ammonia lyase (HAL) catalyzes the elimination of ammonia from the substrate to form (E)-urocanate. The interaction between HAL and acrylic acids or alanines substituted with heteroaryl groups in the beta-position was investigated. These proved to be strong competitive inhibitors when the heteroaryl groups were furanyl, thiophenyl, benzofuranyl, and benzothiophenyl, carrying the alanyl or acrylic side chains either in 2 or 3 positions, with K(i) values between 18 and 139 microM.

Experimental and quantum chemical study on the vibrational spectroscopy of N-methylphenothiazines: part 1.

In this work the authors deal with the vibrational spectroscopy of three derivatives of phenothiazine: the 10-methyl-10H-phenothiazine, the 10 methyl-10H-phenothiazine-3-carbaldehyde and the 10-methyl-10H-phenothiazine-3-yl-methanol. The authors investigated the vibrational spectroscopic behaviour of the phenothiazine skeleton and dealt with the aldehyde and the alcohol substituent effect on the vibrational spectroscopic and structural properties of these skeleton. The infrared and Raman spectra of the compounds have been recorded in condensed state.

Separation of N-alkyl phenothiazine sulfones by HPTLC using an optimum mobile phase.

In high performance thin layer chromatography some form of optimization is necessary if complete separation of all components is required. The selection of mobile phase composition is one of the most important components of an optimization strategies. The aim of this paper is the separation of the N-alkyl phenothiazine sulfones by high performance thin layer chromatography using an optimum mobile phase system.