Yukio Nagata

The Isolation and Characterization of a Cadmium and Zinc-binding Protein from Tetrahymena pyriformis

A cadmium and zinc-binding protein similar to metallothionein has been isolated from Tetrahymena pyriformis exposed to cadmium chloride. This protein contained 32.4% half-cystine, 23.7% acidic amino acids and 10.1% lysine. The amino acid composition was similar to that of copper-thionein of yeast. The metal-binding protein of Tetrahymena pyriformis contained 3.7 g atom cadmium, 0.7 g atom zinc, and O.l g atom copper per mol, and shpwed the spectral characteristics of cadmium-thionein, i.e., a broad shoulder at 250 nm and low residual absorption at 280 nm. The molecular weight of this protein was determined to be 11,000 by gel filtration in 6 M guanidine hydrochloride, although it moved like a protein with a molecular weight of 30,000 on ordinary gel filtration.

Biochemical Studies on the Corticium centrifugum

The fundamental studies on the metabolism of organic acid by Corticium centrifugum have been made, and the following results were obtained. 1) It was identified with mixed melting point and paper chromatography that the organic acid produced by this fungus was only oxalic acid. 2) Thiamine was the growth promoting substance of this fungus, although the relation-ship between added thiamine and accumulated oxalic acid was not proportional. 3) The maximal accumulation of oxalic acid was obtained after one weeks incubation, thereafter, oxalic acid was decomposed by the autolysis of this fungus. 4) The initial pH was optimum at either the neutral or the weakly acidic side; this fungus was resistant to acid and fragile to alkali. Optimal sugar concentration to the formation of oxalic acid by the fungus was apporoximately 5 per cent (sucrose), and relation between growth of the fungus and accumulation of oxalic acid was not proportional, in the case of a variety of sugars being used as the source of C. 5) Peptone as nitrogen source was more effective to maximal accumulation of oxalic acid by this fungus, and potassium nitrate, ammonium phosphate and ammonium sulfate yielded a lower maximal accumulation, in the decreasing order. 6) The effects of inhibitors to growth and oxalic acid formation were examined using fungus matter: The growth of this fungus was completely inhibited by 10-3M of sodium azide, and considerable accumulation of oxalic acid in the culture media was found by the addition of 10-3M monoiodo acetate, whereas thiourea and urethane were not effective.

Studion on the Carbohydrate from the Bulb of Lycoris radiata HERBERT

The mucilage is isolated from cold water extract of the bulb of Lycoris radiata HERBERT by adding the Fehlings solution. And it is confirmed that this mucilage is a glucomannan consisted of one part of glucose and four parts of mannose.