Norihisa Kai

A facile synthesis of naturally occurring binaphthoquinones: efficient oxidative dimerization of 4-alkoxy-1-naphthols using silver(II) oxide-40% nitric acid

Abstract Oxidation of 4-alkoxy-1-naphthols with AgO–40% HNO 3 occurred along with a dimerization to give the corresponding bi-1,4-naphthoquinones. The oxidative dimerization required one hydroxyl group and took place at its ortho position. This reaction was applicable to syntheses of naturally occurring binaphthoquinones, bivitamin K 3 and 3,3′-bijuglone.

A facile synthesis of 6,6′- and 5,5′-dihalogenoindigos

Abstract Our convenient synthetic method for Tyrian purple was applied to syntheses of 6,6′- and 5,5′- dihalogenoindigos. The dihalogenoindigos were easily obtained by three steps of reactions from the commercially available haloindoles. Iodination of the haloindoles, followed by acetoxylation with silver acetate in acetic acid, afforded 5- or 6-halo-3-acetoxyindoles, whose alkaline hydrolysis accompanying air oxidation gave the corresponding dihalogenoindigos. The first 1 H NMR spectrum of 6,6′-difluoroindigo was taken in dimethyl sulfoxide.

Characterization of Yellowfin Tuna (Thunnus albacares, Scombroidei) Tryptophan Hydroxylase

Tryptophan hydroxylase (EC 1.14, 16.4) was purified from yellowfin tuna liver and properties of this enzyme were compared with those of tryptophan hydroxylase from some other species (mouse mastocytoma and rat brain-stem). The molecular weight of the yellowfin tuna enzyme was estimated to be about 280,000 Da. This value is similar to that for the enzymes from mouse mastocytoma and rat brain-stem. On SDS-polyacrylamide gel electrophoresis analysis, yellowfin tuna enzyme was estimated to be about 96,000 Da. This value is different from that for the enzymes from mouse mastocytoma (53,000 Da) and rat brain-stem (59,000 Da) and suggests that yellowfin tuna enzyme may be a dimer of identical subunits of Mr 96,000 Da.

Purification and properties of aromatic L-amino acid decarboxylase from liver of skipjack tuna (Katsuwonus pelamis, Teleostei: Scombridae)

Abstract Aromatic l -amino acid decarboxylase (AADC; EC 4.1.1.28) was extracted from skipjack ( Katsuwonus pelamis ) liver with potassium phosphate buffer solution. This enzyme was purified by ammonium sulfate fractionation, sepharose CL-6B, QAE-Toyopearl 550C, DEAE-Toyopearl 650M, Bio-gel HT, and Toyopearl HW-55F chromatography. The molecular weight of the enzyme was estimated to be about 110,000 by gel filtration on Sepharose CL-6B. The enzyme was inhibited by Co 2+ , Cu 2+ and Zn 2+ ions, but activated by K + , Li + , Na + , Ba 2+ , and Mn 2+ ions.

Characterization of α-amylase from mandarin orange honey

Summary α-Amylase was purified from mandarin orange honey by DEAE-Toyopearl 650M, CM-Toyopearl 650M, and Toyopearl HW-55F column chromatographies, and characterized. The molecular weight of the purified enzyme was estimated to be about 58 kDa by Toyopearl HW-55F gel chromatography and SDS-PAGE, suggesting that the purified enzyme was a monomer. The purified enzyme exhibited optimum activity at pH 5.0 and at 50°C. Inactivation of the enzyme occurred when the pH was lower than 3.0 or higher than 9.0. The enzyme was activated by Co2+, Mn2+, but inhibited by Hg2+, Mg2+, and Fe3+. By TLC analysis, this enzyme was of the α-type that split the interior α-1,4-glycosidic bonds in a random manner. The relative rate of hydrolysis of the polymeric substrate decreased with decreasing percentage of α-1,4-linkages and with increasing percentage of α-1,6-linkages in substrate similar to the results from commercially available honey.

Characteristics of Rice Flour Breads Using Yeast Isolated from Pear Red Bartlett Fruits

To develop high qualities of rice flour breads, we tried to prepare breads using rice flours from major five non-glutinous rice cultivars on market shares of Japan and wild-type Saccharomyces cerevisiae strain YTPR1 isolated from pear Red Bartlett fruits. Apparent amylose contents of rice flours were measured about 12.1-19.9%. Damaged starch contents of these flours were about 22% regardless to the kinds of rice cultivars. Gluten was added about 20 wt.% based on rice flour, and breads were made in the same way. Any bread has caused caving. Next, the amount of water added in dough was regulated in consideration of moisture contents of rice flours. Except for Akitakomachi flour, breads largely expanded, although loaves volumes did not amount to that on bread made from bread flour and commercially available baker’s dried yeast. It was observed correlation between the amount of water and amylose contents of rice flours with R 2 = 0.703. It suggested that the amount of water added in dough might estimate from amylose contents of rice flours. Specific volumes of these loaves were low compared with that made from bread flour. However, by sensory analysis, breads made from Hinohikari and Haenuki flours had total points closest to that made from bread flour: it could produce high quality of breads using Hinohikari and Haenuki flours and yeast isolated from pear Red Bartlett fruits.