We examined the antioxidant activities of various tocopherols (Toc) and their models under as nearly physiological conditions as possible, using egg lecithin liposomes as models of biomembranes. Toc can be exert the antioxidative effects without being oxidized when sufficient Toc to inhibit lipid peroxidation completely were incorporated in the liposome membranes, but when less quantities of Toc were incorporated, they were decomposed with increase in lipid peroxide formation. Cholesterol did not act as an antioxidant, even when incorporated in large amount into the liposome membranes, but it increased the antioxidative efficiency of α-Toc. The activities of Toc on ascorbic acid-Fe^<2+>-induced lipid peroxidation increased in order α-Toc>β-Toc>γ-Toc>δ-Toc>tocol, in agreement with their known order of biological vitamin E potencies. α-Toc model, in which the isoprenoid chain of α-Toc replaced by propionic acid, showed less activity. One molecule each of α-, β-, γ-, δ-Toc and tocol were calculated to be able to protect 220, 120, 100, 30 and 20 molecules, respectively, of polyunsaturated fatty acids. The ratio of α-Toc to polyunsaturated fatty acid moieties corresponds to that of membranes in highly oxygenated tissues such as heart and lung. The possible mechanism of the high efficient inhibitory effects of the Toc on ascorbic acid-Fe^<2+>-induced lipid peroxidation in liposome membranes is discussed.

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D欠乏,並びに正常ニワトリ大腿骨からBGPを分離・精製して,Dのこのタンパク質の性状に及ぼす影響について検討した.この結果,アミノ酸組成,Ca^<2+>結合能,ヒドロキシアパタイト結晶化遅延作用において,D欠乏と正常ニワトリのBGPの差異は観察されなかった.しかしながら,骨のBGP含量はD欠乏により約56%に低下していた. 本論文作成中にニワトリ大腿骨中のBGP含有量に対するDの影響に関する論文がLianら^<22)>によって報告された.

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Nicotinamide deamidase (EC 3.5.1.19) was partially purified from hog liver acetone powder and properties of this enzyme were investigated. Molecular weight of this enzyme was estimated as 180,000 daltons. The enzyme was stable at pH between 6 and 8. The optimum pH of the enzyme reaction was found at 6.8. The K_m value was 0.126 M. This enzyme reaction was inhibited by p-chloromercuribenzoate, Fe^<3+>, Hg^<2+>, Al^<3+> and Co^<2+>. NAD, NADH and N^1_methylnicotinamide were also inhibitory. This enzyme reaction was found to be irreversible. These properties were compared with those of enzymes found in various species, and a possible function of the enzyme in NAD biosynthesis and metabolism was discussed.

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