血清ビタミンB_<12>に関する研究 : (II)人血清中のビタミンB_<12>結合性蛋白質の性状

概要

論文の詳細を見る
The dissociation of the bound form of vitamin B_<12> in the human serum at 100℃ occurred earlier in acetate buffer of pH 4.6 than in phosphate buffers of pH 7.4 and 6.8. The dissociation in acetate buffer was accerelated by adding a small amount of cyanide. Heat stability of the bound form of serum vitamin B_<12> was examined by heating for 30 minutes at various temperatures in phosphate buffer of pH 6.8. Release of the vitamin occurred as follows : 0% at 60℃, 20% at 70℃, 50% at 80℃, 85% at 90℃ and 100% at 100℃. The bound form of serum vitamin B_<12> was almost completely dissociated by the trypsin digestion for 2 hours and three fourths of the bound form were dissociated by the pepsin digestion for 2 hours. Only when the serum was treated with periodate, the vitamin B_<12>-binding ability of α-globulin fraction was lost. Periodate is a potent oxidizing agent which oxidizes many substances including compounds such as glycols and sugars which have alcohol groups on adjacent carbons. From these facts it seems probable that the vitamin B_<12>-binding protein, α-globulin fraction of the serum has a glycoprotein (or mucoprotein) nature.
日本ビタミン学会の論文