Unsaturated and cobalamin saturated transcobalamin I and II in normal human plasma

Abstract

Insolubilized antibody against human transcobalamin I has been used as a specific and precise tool for the separation of transcobalamin I (and III) from transcobalamin II. Range and mean (in parentheses) for the unsaturated binding capacity for twenty samples are 40–190 (90) pmol/l and 220–1170 (560) pmol/l for transcobalamin I (and III) and transcobalamin II, respectively. The similar figures for the cobalamin saturated transcobalamins are 200-549 (320) pmol/l and 75–472 (160) pmol/l. On analyses of the cobalamins attached to each of the transcobalamins, it is shown that methylcobalamin accounts for most of the cobalamins attached to transcobalamin I whereas transcobalamin II carries most of the 5′-deoxyadenosylcobalamin.

Key Words:

• 5′-deoxyadenosylcobalamin
• methylcobalamin
• transcobalamin I
• transcobalamin II
• unsaturated binding capacity