Studies on Free and Serum Protein‐bound Vitamin B₁₂ by the Use of Sephadex G 25 and High Voltage Electrophoresis¹

Serum Protein Binding of Vitamin B1212

“…They also made calculations which show that the total binding capacity of normal serum for vitamin B12 is approximately 2.5 ng./ml., a very small fraction of the total seromuciod of approximately 600 ng./ml. Column chromatographic and high voltage electrophoresis studies by Lindstrand et al (1963), using undialysed CoS7 labeled vitamin BI2, suggested that the radioactivity present in the gamma fraction represented free radioactive vitamin B12, while the radioactivity present with the beta and alpha globulins represented protein-bound vitamin BIZ added in vitro. Occasional inconsistent peaks were seen elsewhere, while the use of a large excess of vitamin B12 was found to produce binding of only a small amount of the added vitamin BIZ.…”