Noncobalamin vitamin B12 analogues in human red cells, liver, and brain.

Analogues of vitamin B12 which appear to be noncobalamin corrinoids appear to be present in human red cells, liver, and brain. Their sources, nature, and effects require study, particularly with reference to their positive and/or negative effects on vitamin B12 metabolism. In normal persons, they are concentrated in liver, with only small quantities in red cells and still smaller quantities in brain. Their concentrations in disease states will be of interest, particularly in persons with varying degrees of neurological damage associated with deficiencies in vitamin B12 or analogue metabolism.