Author
Atsuko Keiyu
Bio: Atsuko Keiyu is an academic researcher from Dow Chemical Company. The author has contributed to research in topics: Steapsin & Mycobacterium smegmatis. The author has an hindex of 2, co-authored 2 publications receiving 56 citations.
Papers
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TL;DR: In this article, Aspergilli and two bacteria hydrolyzed ester 1, and Asp. sojae and Bacillus subtilis var. niger IFO 3108 and Mycobacterium smegmatis ATCC 10143 were screened from 250 type cultures.
Abstract: Microorganisms that hydrolyze methyl 2-phenylpropionate (1) or reduce 4-phenyl-2-butanone (3) were screened from 250 type cultures. Several Aspergilli and two bacteria hydrolyzed ester 1, and Asp. sojae IAM 2703 preferentially hydrolyzed (R)-isomer of (±)-1, whereas Bacillus subtilis var. niger IFO 3108 and Mycobacterium smegmatis ATCC 10143 preferentially hydrolyzed (S)-isomer. The hydrolysis of the related esters of 1 with these organisms was also examined.
34 citations
TL;DR: In this article, enzymes and microorganisms were screened for enantioselective hydrolysis of (±)-1-acetoxy-2, 3-dichloropropane (1) which is convertible to epichlorohydrin.
Abstract: Enzymes and microorganisms were screened for the enantioselective hydrolysis of (±)-1-acetoxy-2, 3-dichloropropane (1) which is convertible to epichlorohydrin. Pancreatin and steapsin from hog pancreas were found to hydrolyze (±)-1 asymmetrically to give (S)-1 of 90% enantiomeric excess (e.e.). From (S)-1 was synthesized the optically pure (S)-isomer of propranolol[1-isopropylamino-3-(1-naphthoxy)-2-propanol], one of the typical β-adrenergic blocking agents.
22 citations
Cited by
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TL;DR: An enzymatic method for the continuous production of (S)−(+)−2−(6‐methoxy‐2‐naphthyl) propionic acid (Naproxen) has been developed and the performance and the productivity of the bioreactor were evaluated as a function of the critical reaction parameters such as temperature, substrate concentration, and product inhibition.
Abstract: An enzymatic method for the continuous production of (S)−(+)−2−(6-methoxy-2-naphthyl) propionic acid (Naproxen) has been developed. The process consists of a stereoselective hydrolysis of the racemic Naproxen ethoxyethyl ester catalyzed by Candida cylindracea lipase. The reaction has been carried out in a continuous-flow closed-loop column bioreactor packed with Amberlite XAD−7, a slightly polor resin on which the lipase has been immobilized by adsorption. Various immobilization conditions as well as the properties of the immobilized lipase have been studied. The performance and the productivity of the bioreactor were evaluated as a function of the critical reaction parameters such as temperature, substrate concentration, and product inhibition. By using a 500-mL column bioreactor, 1.8 kg of optically pure (S)-(+)-Naproxen were produced after 1200 h of continuous operation with a slight loss of the enzymatic activity.
109 citations
DSM1
TL;DR: In this article, the β-blockers can be prepared in optically active form by conventional crystallization procedures, by asymmetric chiral synthesis and by using stereoselective enzymes.
102 citations
TL;DR: In this paper, a review of biological and synthetic preparations of chiral chiral C3 syntons and their applications in organic synthesis is presented. And several of their synthetic applications are also introduced.
Abstract: Epichlorohydrin, 3-chloro-1,2-propanediol and glycidol are versatile chiral C3 syntons in organic synthesis. For the production of these, more efficient and more practical methods are required and many studies have been reported. In this review, biological and synthetic preparations of their synthons and microbial dehalogenation of halohydrins connected with the biological methods are described. Several of their synthetic applications are also introduced.
99 citations
TL;DR: In this article, a new method for the preparation of macrocyclic lactones from ω-hydroxyacid methyl esters is described, which utilizes intramolecular transesterification catalyzed by lipase in organic solvents.
96 citations
TL;DR: The enzyme was shown to be sensitive to very high concentrations of the products formed during the reaction it catalyses, and lysine residues thought to be responsible for this phenomenon were replaced through site-directed mutagenesis.
Abstract: We have screened a new enzyme for the resolution of R, S-naproxen enantiomers. The enzyme is free of lipase activity, and possesses a very high sterospecificity on S-naproxen [2-(6-methoxy-2-naphthyl)-propionic acid] esters and esters of related drugs. The primary structure of the enzyme, determined from the nucleotide sequence, shows limited homology with the catalytic site of lipases. The gene coding for the steroselective carboxylesterase has been cloned and expressed in Bacillus subtilis. Using a multicopy vector and an additional strong promoter an efficient production process was developed. The enzyme was shown to be sensitive to very high concentrations of the products formed during the reaction it catalyses. To increase the resistance of the enzyme, lysine residues thought to be responsible for this phenomnon were replaced through site-directed mutagenesis. Enzymes with improved stability were obtained. An explanation is given in terms of a model in which a reaction of the acid moiety of naproxen with free lysine NH2 groups is a major cause of inactivation.
91 citations