TY - JOUR AU - Balogh Weiser, Diána AU - Boros, Zoltán AU - Hornyánszky, Gábor AU - Tóth, A AU - Poppe, László TI - Disubstituted dialkoxysilane precursors in binary and ternary sol-gel systems for lipase immobilization JF - PROCESS BIOCHEMISTRY J2 - PROCESS BIOCHEM VL - 47 PY - 2012 SP - 428 EP - 434 PG - 7 SN - 1359-5113 DO - 10.1016/j.procbio.2011.11.023 UR - https://m2.mtmt.hu/api/publication/2680477 ID - 2680477 AB - The disubstituted dimethyldiethoxysilane (DMDEOS), methyl(phenyl)diethoxysilane (MPDEOS) and diphenyldiethoxysilane (DPDEOS) were used in binary silane precursor systems in combination with tetraethoxysilane (TEOS) for the immobilization of lipase from Pseudomonas fluorescens (Lipase AK). In addition, ternary silane precursor systems with TEOS and octyltriethoxysilane (OTEOS) or phenyltriethoxysilane (PTEOS) were also studied for encapsulation. The best performing ternary sol–gel preparations (418–736% activity yields of the immobilized enzyme with 1-phenylethanol rac-1a as compared to the native form) were tested as biocatalysts for kinetic resolutions of rac-1a, 1-phenylpropan-2-ol rac-1b and 4-phenylbutan-2-ol rac-1c. Because the catalytic properties and the operational stability of the DMDEOS-containing preparations proved to be superior to all the tested free and sol–gel entrapped Lipase AK biocatalysts in batch mode, the kinetic resolutions of rac-1a and rac-1b were performed with the TEOS/PTEOS/DMDEOS 4:1:1 Lipase AK in a continuous-flow reactor as well. LA - English DB - MTMT ER - TY - JOUR AU - Hellner, G AU - Boros, Zoltán AU - Tomin, A AU - Poppe, László TI - Novel sol-gel lipases by designed bioimprinting for continuous-flow kinetic resolutions JF - ADVANCED SYNTHESIS & CATALYSIS J2 - ADV SYNTH CATAL VL - 353 PY - 2011 SP - 2481 EP - 2491 PG - 11 SN - 1615-4150 DO - 10.1002/adsc.201100329 UR - https://m2.mtmt.hu/api/publication/2667073 ID - 2667073 AB - The bioimprinting effect in sol-gel immobilization of lipases was studied to develop efficient novel immobilized biocatalysts with significantly improved properties for biotransformations in continuous-flow systems. The bioimprinting candidates were selected systematically among the substrate mimics already found in the active site of experimental lipase structures. Four lipases (Lipase AK, Lipase PS, CaLB and CrL) were immobilized by a sol-gel process with nine bioimprinting candidates using various combinations of tetraethoxysilane (TEOS), phenyltriethoxysilane (PhTEOS), octyltriethoxysilane (OcTEOS) and dimethyldiethylsilane (DMDEOS) as silica precursors. The biocatalytic properties of the immobilized lipases were characterized by enantiomer selective acylation of various racemic secondary alcohols in two different multisubstrate systems (mixture A: a series of alkan-2-ols rac-1a–e and mixture B: heptan-2-ol rac-1f and 1-phenylethanol rac-1g). Except with Lipase AK, the most significant activity enhancement was found with the imprinting molecules already found as substrate mimics in X-ray structures of various lipases. The synthetic usefulness of the best biocatalysts was demonstrated by the kinetic resolution of racemic 1-(thiophen-2-yl)ethanol (rac-1h) in batch and continuous-flow systems. LA - English DB - MTMT ER - TY - JOUR AU - Tomin, A AU - Balogh Weiser, Diána AU - Hellner, G AU - Bata, Zsófia AU - Corici, L AU - Péter, F AU - Koczka, Béla AU - Poppe, László TI - Fine tuning the second generation sol-gel lipase immobilization with ternary alkoxysilane precursor systems JF - PROCESS BIOCHEMISTRY J2 - PROCESS BIOCHEM VL - 46 PY - 2011 SP - 52 EP - 58 PG - 7 SN - 1359-5113 DO - 10.1016/j.procbio.2010.07.021 UR - https://m2.mtmt.hu/api/publication/2659767 ID - 2659767 AB - The sol–gel immobilization of Celite-supported lipase from Pseudomonas fluorencens (Lipase AK) was systematically studied using ternary silane precursor systems consisting of alkyltriethoxysilane (alkyl-TEOS), phenyltriethoxysilane (PhTEOS) and tetraethoxysilane (TEOS). The parameters investigated were the surface coverage at various enzyme-Celite ratios (between 1:1 and 1:10) and the effect of molar ratio of alkylTEOS (alkyl = propyl, hexyl, octyl, 1H,1H,2H,2H-perfluorooctyl, decyl, dodecyl, octadecyl), PhTEOS and TEOS (seven series of alkylTEOS:PhTEOS:TEOS from 0.1:0.9:1 to 0.9:0.1:1 in 0.1 steps) on the catalytic properties of the sol–gel biocatalysts. For comparison, the corresponding binary systems (1:1 molar ratios of alkylTEOS:TEOS and PhTEOS:TEOS) were also studied. The ternary and binary sol–gel lipase preparations were evaluated by their catalytic behavior in enantiomer selective acetylation of racemic 1-phenylethanol and 2-heptanol. For each alkylTEOS precursor, one or more alkylTEOS/PhTEOS/TEOS ternary systems were superior biocatalysts compared to the corresponding alkylTEOS/TEOS preparations. The best overall results were achieved with the medium-chain octylTEOS and perfluorooctylTEOS containing ternary systems. LA - English DB - MTMT ER - TY - JOUR AU - Balogh Weiser, Diána AU - Tomin, A AU - Poppe, László TI - Novel solid supports for lipases in sol-gel immobilization systems JF - STUDIA UNIVERSITATIS BABES-BOLYAI CHEMIA J2 - STUD UNIV BABES-BOLYAI CHEM VL - 55 PY - 2010 IS - 4 SP - 283 EP - 288 PG - 6 SN - 1224-7154 UR - https://m2.mtmt.hu/api/publication/2663186 ID - 2663186 AB - Sol-gel encapsulation of lipases proved to be a particularly easy and effective way to enhance the mechanical and catalytic properties of biocatalysts. The sol-gel encapsulated enzymes usually retain their selectivity whereas their heat stability or specific activity may be significantly improved. The aim of our work was to improve the immobilization of lipases in supported sol-gel systems. First, the binding properties of lipase AK on various solid supports were studied. Next, the immobilization properties of the best adsorbent-lipase combinations were tested in sol-gel encapsulation using tetraethoxy-silane/octyltriethoxy-silane/phenyltriethoxy-silane 1/0.7/0.3 silane precursor system. LA - English DB - MTMT ER - TY - JOUR AU - Bódai, V AU - Peredi, R AU - Bálint, J AU - Egri, G AU - Novák, Lajos AU - Szakács, György AU - Poppe, László TI - Novel Hydrolases from Thermophilic Filamentous Fungi for Enantiomerically and Enantiotopically Selective Biotransformations JF - ADVANCED SYNTHESIS & CATALYSIS J2 - ADV SYNTH CATAL VL - 345 PY - 2003 SP - 811 EP - 818 PG - 8 SN - 1615-4150 DO - 10.1002/adsc.200303027 UR - https://m2.mtmt.hu/api/publication/2605143 ID - 2605143 AB - Fourteen thermophilic filamentous fungi were cultivated on two shake flask media and the supernatants were assayed for lipase/carboxylesterase activities using olive-oil, p-nitrophenyl palmitate and p-nitrophenyl butyrate as substrates. The crude enzyme powders (acetone precipitated supernatants) were tested as biocatalysts in organic solvents. Kinetic resolution of racemic 1-phenylethanol (rac-1) and desymmetrisation of 2-acyloxypropan-1,3-diols (3a,b ) by acetylation with vinyl acetate were chosen for testing the biocatalytic abilities of these preparations. The tested biocatalysts proved to be comparable to the commercially available enzymes with respect to the degree of enantiomer selectivity, whereas they exhibited a wider range of enantiotopic selectivity than the most common commercial enzymes. LA - English DB - MTMT ER -