Kano Y, Sakamoto S, Hida K, Suda K, Takaku F
Blood. 1982 Apr;59(4):832-7.
The activities of 5-methyltetrahydrofolate (5-CH3THF) related enzymes and DNA polymerase alpha were determined in bone marrow cells obtained from patients with vitamin B12 deficient megaloblastic anemia and compared with those from healthy volunteers and patients with hemolytic anemia. 5-CH3THF homocysteine methyltransferase activity was significantly lower than that in the control subjects. 5,10-methylenetetrahydrofolate reductase activity was only slightly elevated to that in the control subjects. DNA polymerase alpha activity was significantly higher than that in the control. High deoxyuridine suppression test values in vitamin B12 deficient bone marrow cells were improved by tetrahydrofolate, but not by 5-CH3THF. These data indicate that, even though the reverse reaction catalyzed by 5,10-methylenetetrahydrofolate reductase may be operative in vitamin B12 deficiency, it is not sufficient to correct the disturbance in folate metabolism in vitamin B12 deficiency. Increased DNA polymerase alpha activity may be due to compensation for disarranged DNA synthesis.
测定了维生素B12缺乏的巨幼细胞贫血患者骨髓细胞中5-甲基四氢叶酸（5-CH3THF）相关酶和DNA聚合酶α的活性，并与健康志愿者和溶血性贫血患者的骨髓细胞进行了比较。5-CH3THF同型半胱氨酸甲基转移酶活性显著低于对照组。5,10-亚甲基四氢叶酸还原酶活性仅略高于对照组。DNA聚合酶α活性显著高于对照组。维生素B12缺乏的骨髓细胞中高脱氧尿苷抑制试验值可被四氢叶酸改善，但不能被5-CH3THF改善。这些数据表明，尽管5,10-亚甲基四氢叶酸还原酶催化的逆反应在维生素B12缺乏时可能起作用，但不足以纠正维生素B12缺乏时叶酸代谢的紊乱。DNA聚合酶α活性增加可能是对紊乱的DNA合成的一种补偿。
