The metabolism in man of intravenously injected iodine-labelled trascobalamin I not saturated with cobalamin.
Transcobalamin I not saturated with cobalamin was purified. After iodine-labelling, a fraction of approximately 0.6 retained its cobalamin-binding capacity. Iodinated protein was used for turnover studies in three healthy subjects. The plasma curves obtained were identical to those of iodinated transcobalamin I saturated with cyanocobalamin. The cobalamin-binding capacity of the iodinated protein was determined on microcolumns containing insolubilized cobalamin. The binding capacity decreased rapidly, only 50% of the initial unsaturated cobalamin-binding capacity remaining after 0.2 to 0.3 days. It is concluded that the turnover of transcobalamin I not saturated with cobalamin does not differ from the turnover of transcobalamin I saturated with cyanocobalamin, and that transcobalamin I saturated with cobalamin in vivo is metabolized at the same rate as is transcobalamin I saturated with cyanocobalamin in vitro.
D000328:Adult; D001798:Blood Proteins / Q000097:blood*; D003404:Creatinine / Q000097:blood; D005260:Female; D006451:Hemoglobin, Sickle / Q000378:metabolism; D006801:Humans; D007467:Iodoproteins / Q000097:blood / Q000302:isolation & purification; D008297:Male; D010953:Plasma Volume; D014155:Transcobalamins / Q000097:blood* / Q000302:isolation & purification; D014805:Vitamin B 12
D001798:Blood Proteins; D006451:Hemoglobin, Sickle; D007467:Iodoproteins; D014155:Transcobalamins; D003404:Creatinine; D014805:Vitamin B 12