Enhancement of phenolic compounds oxidation using laccase from Trametes versicolor in a microreactor

Laccases catalyse the oxidation of a wide range of substrates by a radical-catalyzed reaction mechanism, with a corresponding reduction of oxygen to water in a four-electron transfer process. Due to that, laccases are considered environmentally friendly enzymes, and lately there has been great interest in their use for the transformation and degradation of phenolic compounds. In this work, enzymatic oxidation of catechol and L-DOPA using commercial laccase from Trametes versicolor was performed, in continuously operated microreactors. The main focus of this investigation was to develop a new process for phenolic compounds oxidation, by application of microreactors. For a residence time of 72 s and an inlet oxygen concentration of 0.271 mmol/dm³, catechol conversion of 41.3% was achieved, while approximately the same conversion of L-DOPA (45.0%) was achieved for an inlet oxygen concentration of 0.544 mmol/dm³. The efficiency of microreactor usage for phenolic compounds oxidation was confirmed by calculating the oxidation rates; in the case of catechol oxidation, oxidation rates were in the range from 76.101 to 703.935 g/dm³/d (18–167 fold higher, compared to the case in a macroreactor). To better describe the proposed process, kinetic parameters of catechol oxidation were estimated, using data collected from experiments performed in a microreactor. The maximum reaction rate estimated in microreactor experiments was two times higher than one estimated using the initial reaction rate method from experiments performed in a cuvette. A mathematical model of the process was developed, and validated, using data from independent experiments.     

Transport of iodide in structured soil under spring barley during irrigation experiment analyzed using dual-continuum model

Transport of radioactive iodide ¹³¹I^? in a black clay loam soil under spring barley in an early ontogenesis phase was monitored during controlled field irrigation experiment. It was found that iodide bound in the soil matrix could be mobilized by the surface leaching enhanced by mechanical impact of water drops and transported below the root zone of crops via soil cracks. The iodide transport through structured soil profile was simulated by the one-dimensional dual-continuum model, which assumes the existence of two inter-connected flow domains: the soil matrix domain and the preferential flow domain. The model predicted relatively deep percolation of iodide within a short time, in a good agreement with the observed vertical iodide distribution in soil. The dual-continuum approach proved to be an adequate tool for evaluation of field irrigation experiments conducted in structured soils.     

Prostate-cancer-targeted N-(2-hydroxypropyl)methacrylamide copolymer/docetaxel conjugates

Biodistribution, pharmacokinetics, and efficacy of prostate-cancer-targeted HPMA copolymer/DTX conjugates are evaluated in nude mice bearing prostate cancer C4-2 xenografts. PSMA-specific monoclonal antibodies 3F/11 are used as the targeting moiety. Control conjugates tumor accumulation to total background organs (heart, lung, kidney, liver, spleen and blood) accumulation increase substantially with time for the targeted conjugate, and the ratio at 48 h is 7-fold higher than that at 6 h. Preliminary evaluation of the efficacy of the conjugates in vivo show tumor growth inhibition for all HPMA copolymer/DTX conjugates.     

Ureter Regeneration–The Proper Scaffold Has to Be Defined

The aim of this study was to compare two different acellular scaffolds: natural and synthetic, for urinary conduit construction and ureter segment reconstruction. Acellular aortic arch (AAM) and poly(L-lactide-co-caprolactone) (PLCL) were used in 24 rats for ureter reconstruction in both tested groups. Follow-up period was 4 weeks. Intravenous pyelography, histological and immunohistochemical analysis were performed. All animals survived surgical procedures. Patent uretero-conduit junction was observed only in one case using PLCL. In case of ureter segment reconstruction ureters were patent in one case using AAM and in four cases using PLCL scaffolds. Regeneration of urothelium layer and focal regeneration of smooth muscle layer was observed on both tested scaffolds. Obtained results indicates that synthetic acellular PLCL scaffolds showed better properties for ureter reconstruction than naturally derived acellular aortic arch.     

Baeyer-Villiger oxidation of DHEA, pregnenolone, and androstenedione by Penicillium lilacinum AM111

The Baeyer-Villiger monooxygenase (BVMO) produced by Penicillium lilacinum AM111, in contrast to other enzymes of this group known in the literature, is able to process 3beta-hydroxy-5-ene steroid substrates. Transformation of DHEA and pregnenolone yielded, as a sole or main product, 3beta-hydroxy-17a-oxa-d-homo-androst-5-en-17-one, a new metabolite of these substrates; pregnenolone was transformed also to testololactone. Testololactone was the only product of oxidation of androstenedione by P. lilacinum AM111. Investigations of the time evolution of reaction progress have indicated that the substrates stimulate activity of BVMO(s) of P. lilacinum AM111.     

Production,purification and oxidative folding of the mouse recombinant prior protein

The method leading to overexpression of the full-length mouse recombinant prion protein (mrPrP 23-231) in the cytoplasm of E. coli as a his-PrP fusion protein and its effective purification using affinity chromatography is described. A typical yield of the method was 8-10 mg his-mrPrP per L of the bacterial culture. The purity of purified protein was > 95 %. The purified his-mrPrP was converted to a soluble form and its folding to alpha-helical and beta-sheet conformations was studied. The properties of differently folded mrPrP were determined by measuring their circular dichroism spectra, partial resistance to cleavage by proteinase K and by centrifugation in sucrose gradient.     

Single Nucleotide Variants in KIF14 Gene May Have Prognostic Value in Breast Cancer

Molecular Diagnosis & Therapy - Human kinesin 14 (KIF14) is one of the 70 prognostic marker genes (so-called Amsterdam profile) previously identified by the microarray of breast carcinomas, and...