Moritsugu Hamada

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.