Tetsuo Omata

Application of photo-crosslinkable resin prepolymers to entrap microbial cells. Effects of increased cell-entrapping gel hydrophobicity on the hydrocortisone Δ1-Dehydrogenation

SummaryAcetone-dried cells of Arthrobacter simplex, whose steroid Δ1 activity had been previously induced, were entrapped by the use of photo-crosslinkable resin prepolymers. When the hydrophobicity of the cell-entrapping gel was increased by mixing a hydrophobic prepolymer (main chain component; polypropyleneglycol) with a hydrophilic prepolymer (main chain component; polypropyleneglycol) with a hydrophilic prepolymer (main chain component; polyethyleneglycol) (up to 30%), the hydrocortisone to prednisolone conversion rate of the immobilized cells increased significantly, attaining approximately 20% of that of the free cells. A 10% addition of organic solvents, such as methanol, to the aqueous reaction mixture enhanced the solubility of the substrate greatly and to a lesser degree the reaction rate of the immobilized cells. The presence of an electron acceptor, phenazine methosulfate or 2,6-dichlorophenolindophenol, stimulated the steroid conversion of the entrapped as well as the free cells. The stability of the entrapped cells over repeated reactions was improved by immobilization.

Stereoselective hydrolysis of dl-menthyl succinate by gel-entrapped Rhodotorula minuta var. texensis cells in organic solvent

Summarydl-Menthyl succinate was successfully hydrolyzed stereoselectively by Rhodotorula minuta var. texensis cells entrapped within photo-crosslinked or polyurethane resin gels in water-saturated n-heptane. The hydrolyzed product was found to be pure l-menthol. The catalytic activity of the immobilized cells, especially those entrapped in urethane polymers, was far more stable than that of the free cells. The half-life of the polyurethaneentrapped cells was estimated to be 55–63 days in the organic solvent.

Immobilization of microbial cells and enzymes with hydrophobic photo-crosslinkable resin prepolymers

SummaryAttempts were made to entrap enzymes or microbial cells with water-insoluble photo-crosslinkable resin prepolymers of different types in organic solvent systems in the presence or absence of water. Acetone-dried cells of Artbrobacter simplex immobilized in a maleic polybutadiene gel (PBM-2000) converted hydrocortisone to prednisolone in a phosphate buffer. 4-Androstene-3,17-dione was converted to androst-1,4-diene-3,17-dione in benzene-n-heptane solution by Nocardia rhodocrous which was immobilized by a hydrophobic prepolymer, ENTP-2000. The ENTP-2000 had been synthesized from poly(propylene glycol)-2000, hydroxyethylacrylate and isophorone diisocyanate. Even enzymes catalyzing aqueous phase reactions, such as catalase and invertase, were immobilized in a polybutadiene resin (PB-200k) to give active gel-entrapped preparations. The cells and enzymes immobilized in these hydrophobic resins exhibited moderate activities compared with those of the free cells and enzymes.

Bioconversion of lipophilic compounds in non-aqueous solvent. Effect of gel hydrophobicity on diverse conversions of testosterone by gel-entrapped Nocardia rhodocrous cells

SummaryThe bioconversion of testosterone (TS) in water-saturated benzene-n-heptane (4:1 by volume) was mediated by Nocardia rhodocrous cells whose steroid Δ1-dehydrogenase and 17β-hydroxysteroid dehydrogenase were induced by TS. TS was transformed into 4-androstene-3,17-dione (4-AD), dehydrotestosterone (DTS) and 1,4-androstadiene-3, 17-dione (ADD) by incubating with the cell suspensions in the presence of phenazine methosulfate (PMS). Time-courses of TS transformation revealed that DTS and 4-AD were produced initially and further oxidized to ADD. Thus, the final product, ADD; was formed via two different pathways: TS→4-AD→ADD and TS→DTS→ADD. In these routes, Δ1-dehydrogenation required PMS, while 17β-dehydrogenation could proceed without any exogenous electron acceptor. N. rhodocrous cells entrapped in hydrophilic gels (H-gel) and lipophilic gels (L-gel) prepared by photo-crosslinkable resin prepolymers and urethane prepolymers were useful for effective dehydrogenations of TS. The cells entrapped in L-gels produced 4-AD as the major product, whereas DTS was the main product by the cells in H-gel. The difference in the profiles of dehydrogenation products can be explained by low affinity of PMS for L-gel-entrapped cells and of TS for H-gel-entrapped cells. Inhibitory effect of DTS on 17β-hydroxysteroid dehydrogenase also would be responsible for the accumulation of DTS in the latter case. Thus, different routes for product formation could be selected by using resin prepolymers of appropriate hydrophilicity or hydrophobicity for entrapment of biocatalysts.

Lipase-catalyzed kinetic resolution of methyl 4-hydroxy-5-tetradecynoate and its application to a facile synthesis of japanese beetle pheromone

Abstract A kinetic resolution of methyl 4-hydroxy-5-tetradecynoate is accomplished by a lipase-catalyzed enantioselective acylation in organic solvent. Acylation of methyl 4-hydroxy-5-tetradecynoate with succinic anhydride in an organic solvent yields methyl (R)-4-succinoyloxy-5-tetradecynoate with over 90% e.e.. Furthermore, this optically active diester was converted to (R)-5-(1-decynyl)oxacyclopentan-2-one by lipase-catalyzed enantioselective lactonization which enhanced its e.e. over 99%. The Japanese beetle pheromone (R,Z)-(-)-5-(1-decenyl)oxacyclopentan-2-one is synthesized in one step from this optically active lactone.

Efficient kinetic resolution of organosilicon compounds by stereoselective esterification with hydrolases in organic solvent

Stereoselective esterification of three isomers of trimethylsilylpropanol, 1-trimethylsilyl-2-propanol, 1-trimethylsilyl-1-propanol, and 2-trimethylsilyl-1-propanol, was systematically studied with five kinds of hydrolases in an organic solvent system in connection with the structure of the compounds. The hydrolases were found to be able to esterify these organosilicon compounds, even β-hydroxyalkylsilanes, which are unstable under the conditions of acid-catalysed esterification, and the highly optically active organosilicon compounds were successfully prepared with the selected hydrolases. Even a primary alcohol, 2-trimethylsilyl-1-propanol, was stereoselectively esterified by lipase. Furthermore, comparative studies were made by using their carbon counterparts. The silicon atom in the substrates was found to enhance the enzyme stereoselectivity in some cases, but its effect on the substrate reactivity was dependent on the structure of the substrates. These results are discussed based on the specific characters of the silicon atom.

Application of Immobilized Biocatalysts to Bioconversion in Hydrophobic Conditions

New methods to entrap biocatalysts with photo-crosslinkable resin prepolymers and urethane resin prepolymers of either hydrophilic or hydrophobic character have been developed. Steroids having a hydrophilic group at C-17 position were dehydrogenated (4-androstene-3,17-dione to androstene-1,4-diene-3,17-dione and dehydroepiandrosterone to 4-androstene-3,-17-dione) in an organic solvent by Nocardia rhodocrous cells entrapped with either hydrophilic prepolymers. In the cases of highly hydrophobic steroids having an aliphatic side chain at C-17 position, such as cholesterol, β-sitosterol and stigmatsterol, however, transformation to the corresponding 3-keto-Δ4 -steroids was achieved in a non-polar organic solvent only by the cells entrapped with hydrophobic prepolymers. Thus, advantage of hydrophobic gels is the bioconversion of highly hydrophobic compounds has been observed clearly. The steroid transformation activities of the gel-entrapped cells were closely correlated to the partition coefficients of substrates (and in some cases, to those of cofactors) between gels and external solvents.

Lipase-catalyzed kinetic resolution of 2,3-epoxy-8-methyl-1-nonanol, the key intermediate in the synthesis of the gypsy moth pheromone

Abstract Lipase-catalyzed enantioselective acylation of (±)-2,3-epoxy-8-methyl-1-nonanol with acetic anhydride in diisopropyl ether yielded (2S, 3R)-1-acetoxy-2,3-epoxy-8-methylnonane with 79% enantiomeric excess (ee). The optical purity of the epoxy ester was improved up to 95% ee by a second step of lipase-catalyzed enantioselective alcoholysis in diisopropyl ether.

Synthesis of the Enantiomers of (Z)-5(1-Octenyl)oxacyclopentan-2-one, a Sex Pheromone of the Cupreous Chafer Beetle, Anomala cuprea Hope

Synthesis of the Enantiomers of (Z)-5-(1Octenyl)oxacyclopentan-2-one, a Sex Pheromone of the Cupreous Chafer Beetle, Anomala cuprea Hope Eiichiro Fukusaki, Shuji Senda, Yutaka Nakazono & Tetsuo Omata To cite this article: Eiichiro Fukusaki, Shuji Senda, Yutaka Nakazono & Tetsuo Omata (1992) Synthesis of the Enantiomers of (Z)-5-(1-Octenyl)oxacyclopentan-2-one, a Sex Pheromone of the Cupreous Chafer Beetle, Anomala cuprea Hope, Bioscience, Biotechnology, and Biochemistry, 56:7, 1160-1161, DOI: 10.1271/bbb.56.1160 To link to this article: http://dx.doi.org/10.1271/bbb.56.1160

Lipase-catalyzed kinetic resolution of 2,3-epoxy-1-tridecanol and its application to facile synthesis of (+)-disparlure.

Acylation of (+/-)-2,3-epoxy-1-tridecanol with acetic anhydride in diisopropyl ether by porcine pancreatic lipase yielded (2R, 3S)-2,3-epoxy-1-tridecanol as the remaining substrate with an optical purity of over 99% ee. (+)-Disparlure was synthesized in two steps from this optically active epoxy alcohol.