Yoichi Mikami
Tokyo Laboratory
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Featured researches published by Yoichi Mikami.
Applied and Environmental Microbiology | 2003
Nobuyuki Horinouchi; Jun Ogawa; Takafumi Sakai; Takako Kawano; Seiichiro Matsumoto; Mie Sasaki; Yoichi Mikami; Sakayu Shimizu
ABSTRACT The gene encoding a deoxyriboaldolase (DERA) was cloned from the chromosomal DNA of Klebsiella pneumoniae B-4-4. This gene contains an open reading frame consisting of 780 nucleotides encoding 259 amino acid residues. The predicted amino acid sequence exhibited 94.6% homology with the sequence of DERA from Escherichia coli. The DERA of K. pneumoniae was expressed in recombinant E. coli cells, and the specific activity of the enzyme in the cell extract was as high as 2.5 U/mg, which was threefold higher than the specific activity in the K. pneumoniae cell extract. One of the E. coli transformants, 10B5/pTS8, which had a defect in alkaline phosphatase activity, was a good catalyst for 2-deoxyribose 5-phosphate (DR5P) synthesis from glyceraldehyde 3-phosphate and acetaldehyde. The E. coli cells produced DR5P from glucose and acetaldehyde in the presence of ATP. Under the optimal conditions, 100 mM DR5P was produced from 900 mM glucose, 200 mM acetaldehyde, and 100 mM ATP by the E. coli cells. The DR5P produced was further transformed to 2′-deoxyribonucleoside through coupling the enzymatic reactions of phosphopentomutase and nucleoside phosphorylase. These results indicated that production of 2′-deoxyribonucleoside from glucose, acetaldehyde, and a nucleobase is possible with the addition of a suitable energy source, such as ATP.
Bioscience, Biotechnology, and Biochemistry | 2003
Jun Ogawa; Kyota Saito; Takafumi Sakai; Nobuyuki Horinouchi; Takako Kawano; Seiichiro Matsumoto; Mie Sasaki; Yoichi Mikami; Sakayu Shimizu
2-Deoxyribose 5-phosphate was produced from acetaldehyde and dihydroxyacetone phosphate via D-glyceraldehyde 3-phosphate by Klebsiella pneumoniae B-4-4 through deoxyriboaldolase- and triosephosphate isomerase-catalyzing reactions. Under the optimum conditions, 98.7 mM 2-deoxyribose 5-phosphate was produced from 200 mM acetaldehyde and 117 mM dihydroxyacetone phosphate in 2 h with a molar yield of 84%. The 2-deoxyriobse 5-phosphate produced was directly transformed to 2′-deoxyribonucleoside by phosphopentomutase- and nucleoside phosphorylase-catalyzing reactions.
Bioscience, Biotechnology, and Biochemistry | 1993
Michiko Aoki; Motomu Tan; Atsushi Fukushima; Tadaharu Hieda; Susumu Kubo; Michiyo Takabayashi; Kuniaki Ono; Yoichi Mikami
Inhibitors of plant virus infection with systemic effects were found in the culture filtrates of Basidiomycetes such as Fomes fomentarius and Schizophyllum commune. These inhibitors were widely distributed in Agaricales and Polyporales. The inhibitors designated as BAS (Basidiomycete Antiviral Substance) were highly active against the mechanical transmission of tobacco mosaic virus (TMV). No toxic effect was observed on the host plants. BAS-F, a polysaccharide produced by F. fomentarius, almost completely inhibited infection, when BAS-F at 2 μg/ml was applied to the same surface of leaves of Xanthi-nc tobacco 24 h before TMV inoculation to the upper surface of the leaves, and 500/0 inhibition was shown when BAS-F at 10 μg/ml was applied to the under surface of leaves. BAS-F also induced systemic resistance to the non-treated leaves when it was applied to only one leaf of the plant. BAS-F also had similar effects against the infection of TMV on bell pepper and tomato plants.
Bioscience, Biotechnology, and Biochemistry | 2006
Nobuyuki Horinouchi; Jun Ogawa; Takako Kawano; Takafumi Sakai; Kyota Saito; Seiichiro Matsumoto; Mie Sasaki; Yoichi Mikami; Sakayu Shimizu
2-Deoxyribose 5-phosphate production through coupling of the alcoholic fermentation system of baker’s yeast and deoxyriboaldolase-expressing Escherichia coli was investigated. In this process, baker’s yeast generates fructose 1,6-diphosphate from glucose and inorganic phosphate, and then the E. coli convert the fructose 1,6-diphosphate into 2-deoxyribose 5-phosphate via D-glyceraldehyde 3-phosphate. Under the optimized conditions with toluene-treated yeast cells, 356 mM (121 g/l) fructose 1,6-diphosphate was produced from 1,111 mM glucose and 750 mM potassium phosphate buffer (pH 6.4) with a catalytic amount of AMP, and the reaction supernatant containing the fructose 1,6-diphosphate was used directly as substrate for 2-deoxyribose 5-phosphate production with the E. coli cells. With 178 mM enzymatically prepared fructose 1,6-diphosphate and 400 mM acetaldehyde as substrates, 246 mM (52.6 g/l) 2-deoxyribose 5-phosphate was produced. The molar yield of 2-deoxyribose 5-phosphate as to glucose through the total two step reaction was 22.1%. The 2-deoxyribose 5-phosphate produced was converted to 2-deoxyribose with a molar yield of 85% through endogenous or exogenous phosphatase activity.
Bioscience, Biotechnology, and Biochemistry | 1992
Nobuaki Hori; Kyouko Uehara; Yoichi Mikami
5-Methyluridine (5MU) was synthesized efficiently from adenosine, thymine, and phosphate by a combination of adenosine deaminase (ADA), purine nucleoside phosphorylase (PUNP), pyrimidine nucleoside phosphorylase (PYNP), and xanthine oxidase (XOD). Adenosine was converted into inosine first by ADA. 5MU and hypoxanthine were synthesized from inosine and thymine by PUNP and PYNP. The hypoxanthine formed was converted into urate via xanthine by XOD. After inosine was completely consumed, an equilibrium state, in which 5MU, thymine, ribose-1-phosphate, and phosphate were involved, was achieved. At the equilibrium state, the maximum yield of 5MU was obtained. The yield of 5MU was 74%, when the initial concentrations of adenosine, thymine, and phosphate were 5 mM each. On the other hand, in the absence of ADA or XOD the yield of 5MU was 1.8%. Several kinds of nucleosides were also synthesized with high yield by the same method.
Applied Microbiology and Biotechnology | 2006
Nobuyuki Horinouchi; Jun Ogawa; Takako Kawano; Takafumi Sakai; Kyota Saito; Seiichiro Matsumoto; Mie Sasaki; Yoichi Mikami; Sakayu Shimizu
Biotechnology Letters | 2006
Nobuyuki Horinouchi; Jun Ogawa; Takako Kawano; Takafumi Sakai; Kyota Saito; Seiichiro Matsumoto; Mie Sasaki; Yoichi Mikami; Sakayu Shimizu
Archive | 1998
Ayumi Hasegawa; Seiichiro Matsumoto; Yoichi Mikami; Yonosuke Sunaga; Shinjhi Yoshinaka
Archive | 1987
Koji Hayade; Nobuaki Hori; Masao Karube; Yoichi Mikami; Takeshi Yanagimoto
New Biotechnology | 2009
Nobuyuki Horinouchi; Takako Kawano; Takafumi Sakai; Seiichiro Matsumoto; Mie Sasaki; Yoichi Mikami; Jun Ogawa; Sakayu Shimizu