title: Transplacental transport in the rabbit of vitamin B12 bound to human transcobalamin I, II and III.
abstract: Transcobalamins I, II and III (TCI, TCII, TCIII) were purified from human serum, saturated with 57Co-vitamin B12 (57Co-B12), and injected into pregnant rabbits. Whole body retention of the 57Co-B12 averaged 91% and was similar for each of the three vitamin B12 binders. A maximum of 62% of the injected 57Co-B12 was found in fetal tissues when the vitamin was injected bound to TCII, but only 6--7% when bound to TCI or TCIII. Thus TCII is responsible for the delivery of vitamin B12 to the fetus.
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism*; D005260:Female; D005333:Fetus / Q000378:metabolism; D006801:Humans; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011485:Protein Binding; D011817:Rabbits; D013997:Time Factors; D014155:Transcobalamins / Q000378:metabolism*; D014805:Vitamin B 12 / Q000378:metabolism*
chemical_list: D001798:Blood Proteins; D014155:Transcobalamins; D014805:Vitamin B 12