Mitsui Toatsu Chemicals, Incorporated

Mitsui Chemicals, Inc.

Mitsu Chemicals, Inc.

Nobuhiro Fukuhara

Setsuo Yoshino

Yoshiyuki Nakajima

Satori Sone

Nobuyoshi Makiguchi

Maki Suzuki

Kaoru Yamamoto

Toshihiro Oikawa

Yasuko Matsuba

Daisuke Ura

Toshio Matsumoto

Hitoki Miyake

Masami Osabe

Mitsuo Koito

Tooru Miyahara

Tadashi Hashimukai

Tomoyuki Se

Kazuhiro Fukuta

Makoto Yanaka

Amino acid sequence of L-phenylalanine ammonia-lyase

A purified N-t-butoxycarbonylphenylalanine ester preparation having an enhanced optical activity can be obtained by bringing an N-t-butoxycarbonylphenylalanine ester preparation containing an optically active compound into contact with an aliphatic hydrocarbon, extracting the optically active compound with the aliphatic hydrocarbon, and recovering the optically active compound from the resulting extract.

Process for preparing N-t-butoxycarbonylphenylalanine ester

Optically active chroman-3-acetic acids and optically active chroman-3-acetic acid esters can be obtained by treating a mixture of (3R)- and (3S)-chroman-3-acetic esters of formula (I)

Esterase and methods for the production of optically active chroman compounds

Optically active chroman-3-acetic acids and optically active chroman-3-acetic acid esters can be obtained by treating a mixture of (3R)- and (3S)-chroman-3-acetic esters of formula (I) ##STR1## [wherein R.sub.1 is a straight or branched alkyl group having 1-5 carbon atoms and R.sub.2 is a hydrogen atom or substituted or unsubstituted amino group]

Esterase and methods for the production of optically active chroman

S-phenyl-L-cysteine can be produced in a high yield by reacting thiophenol and L-serine under the action of tryptophan synthase at a pH in a range of from 9.0 to 10.5. Purification of S-phenyl-L-cysteine obtained by this enzyme reaction can be effectively achieved by adjusting the pH of a crystal-containing reaction mixture to a strongly acidic level of 1.5 or lower to dissolve crystals of S-phenyl-L-cysteine, adding activated carbon to the pH-adjusted mixture, maintaining the resultant mixture at a temperature of from 20.degree. to 60.degree. C. under aeration with an oxygen-containing gas, subjecting the thus-obtained mixture to filtration, raising the pH of the resulting filtrate back to a range of from 2.5 to 6.0 to precipitate crystals of S-phenyl-L-cysteine and then recovering the thus-precipitated crystals.

Production process of S-phenyl-L-cysteine

The invention relates to a process for preparing L-serine from glycine and formaldehyde in the presence of cells of a microorganism or a cell-treated product having a serine hydroxymethyl transferase activity by an enzymatic method.

Process for the preparation of L-serine by an enzymatic method

Escherichia coil carrying a hybrid plasmid having been constructed by inserting a desired foreign gene into an expression vector so as to permitting expression of said desired foreign gene therein was cultured at a temperature 40.degree. C. or over so that the expression of said desired foreign gene was suppressed. This E. coil (i.e., transformant) was cultured at 40.degree. C. or over in a first process to suppress the expression of the foreign gene and to support sufficient cell growth and thereafter below 40.degree. C. in a second process to release the suppression of the expression so as to permit effective production of the foreign gene product, which resulted in high concentration of the foreign gene product in the final culture.

Method of regulating expression of a foreign gene by controlling culture

L-Phenylalanine is isolated in pure form from an aqueous solution thereof containing cinnamic acid by subjecting the aqueous solution to toluene extraction to extract cinnamic acid therefrom; separating the toluene phase; and then concentrating the aqueous phase, until crystals of L-phenylalanine form therein, while concurrently separating the crystalline L-phenylalanine from the liquid aqueous phase.

Method for purifying L-phenylalanine

Escherichia coli carrying a hybrid plasmid having been constructed by inserting a desired foreign gene into an expression vector so as to permitting expression of said desired foreign gene therein was cultured in a medium containing a sugar component utilizable by the E. coli as a carbon source at a concentration of 0.3% or more so that the expression of said desired foreign gene was suppressed. This E. coli (i.e., transformant) was cultured in the medium in which the sugar concentration was maintained at 0.3% or more in a first process so as to supress the suppression of the foreign gene and to support sufficient cell growth and thereafter at less than 0.3% in a second process to release the suppression of the expression so as to permit effective production of the foreign gene product, which resulted in high concentration of the foreign gene product in the final culture.

Method of regulating expression of a foreign gene by controlling the

Escherichia coli carrying a hybrid plasmid having been constructed by inserting a desired foreign gene into an expression vector so as to permitting expression of said desired foreign gene therein was cultured at a temperature 40.degree. C. or over so that the expression of said desired foreign gene was suppressed. This E. coli (i.e., transformant) was cultured at 40.degree. C. or over in a first process to suppress the expression of the foreign gene and to support sufficient cell growth and thereafter below 40.degree. C. in a second process to release the suppression of the expression so as to permit effective production of the foreign gene product, which resulted in high concentration of the foreign gene product in the final culture.

A recombinant plasmid for the expression of phenylalanine ammonia-lyase (PAL) is constructed by incorporating therein a combined promoter comprising (a) the fusion promoter (the tac promoter) composed of the trp promoter minus 35 region and the lac UV-5 promoter minus 10 region and (b) the P.sub.L promoter of the lambda phage, the tac promoter and the P.sub.L promoter being connected so as to have the same directional property. This recombinant plasmid permits more efficient expression of in Escherichia coli.

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Fukuoka, Japan

Nobuhiro Fukuhara