Fumio Ibuki

Chemical reactivity of the nucleic acid bases. I. Antioxidative ability of the nucleic acids and their related substances on the oxidation of unsaturated fatty acids

Abstract The nucleic acids und their related substances exhibit antioxidative effects on the oxidation of linoleic acid by air. Especially adenine, guanosine, xanthine, hypoxanthine, uric acid, uracil, orotic acid, and ribonucleic acid were as effective antioxidants as α-tocopherol, nordihydroguaiaretic acid, and butylhydroxyanisole. Nucleic acids and their related substances may be used as antioxidants for lipids.

Decreased Antioxidative Activity of Maize Zein in Response to Deamidation Rate

Ten samples with different deamidation rates were prepared from commercially available maize zein by heat treating with 0.05 n HCl in 70% ethanol, and were examined for their antioxidative activity in simply mixed protein-fatty acid (10:1) model systems at moderate humidity. A regression line with a correlation coefficient of r = - 0.946 was obtained, when the linoleate/palmitate ratio on day 3 was plotted against the percentage of deamidation.

Interactions of κ-Casein Components with αs1-and β-Caseins

κ-Casein components having various carbohydrate contents were prepared by diethylaminoethyl-cellulose chromatography and the interactions of each κ-casein component both with αs1-casein and with β-casein were examined by Sepharose 4B gel chromatography, ultra-centrifugal experiments and viscosity measurements. Each κ-casein component could form complex with αs1- and β-casein in the absence and presence of CaCl2. Molecular weight of complexes of unfractionated κ-casein both with αs1-casein and with κ-casein were about 70 × 104 at 37°C in the absence of CaCl2, while those of complexes of each κ-casein component with αs1 and β-casein were about 50 × 104. Stokes radii of complexes increased with increasing calcium ion. While sedimentation coefficient at 37°C of complex with β-casein had almost the same value, those of complexes with αs1-casein decreased with increase of carbohydrate content of κ-casein components. Intrinsic viscosity of complex of κ-casein component having much carbohydrate was almost the sam...