Baker H, Frank O, Khalil F, DeAngelis B, Hutner S H
J Am Coll Nutr. 1986;5(5):467-75. doi: 10.1080/07315724.1986.10720150.
Metabolically active B12 analogs and inactive B12 analogs were measured in plasma, red blood cells (RBC), and pooled pernicious anemia serum. B12 values by Lactobacillus leichmannii, Escherichia coli, Euglena gracilis, and radioisotope dilution method (RIDA) as assays for total B12 (active analogs + inactive analogs) were compared to Ochromonas malhamensis values as index of only metabolically active B12. B12 values above those with O malhamensis distinguished inactive analogs from active B12. Inactive analogs contribute 85, 97, 135, and 163% above active B12 activity in normal plasma when E gracilis, L leichmannii, RIDA, and E coli, respectively, were used for B12 analysis. RIDA B12 determinations for active B12 in plasma showed that 44% of the B12 measured was still due to inactive analogs when compared to O malhamensis B12 activity. Inactive B12 analogs contributed 21, 151, and 224% above O malhamensis active B12 in RBC when E gracilis, L leichmannii, and E coli, respectively, were used.
在血浆、红细胞（RBC）和合并的恶性贫血血清中测量了代谢活性维生素B12类似物和无活性维生素B12类似物。将用赖氏乳杆菌、大肠杆菌、纤细裸藻和放射性同位素稀释法（RIDA）测定的总维生素B12（活性类似物+无活性类似物）的维生素B12值与作为仅代谢活性维生素B12指标的马尔哈姆赭球藻值进行比较。高于马尔哈姆赭球藻测定值的维生素B12值区分了无活性类似物和活性维生素B12。当分别使用纤细裸藻、赖氏乳杆菌、RIDA和大肠杆菌进行维生素B12分析时，正常血浆中无活性类似物在活性维生素B12活性之上的贡献分别为85%、97%、135%和163%。血浆中活性维生素B12的RIDA测定表明，与马尔哈姆赭球藻维生素B12活性相比，所测维生素B12中44%仍归因于无活性类似物。当分别使用纤细裸藻、赖氏乳杆菌和大肠杆菌时，红细胞中无活性维生素B12类似物在马尔哈姆赭球藻活性维生素B12之上的贡献分别为21%、151%和224%。
