ABSTRACT
In 1926 Whipple et al. (1) described the successful treatment of dogs with an experimental form of anemia by feeding them with large amounts of raw liver. In the same year Minot and Murphy (2) showed that this treatment was equally effective in patients with pernicious anemia. However, it took another 20 years of research to isolate and identify the active substance: vitamin B12, or cyanocobalamin. The red-colored material was isolated from liver in crystalline form almost simultaneously by Folkers and coworkers (3) in the United States and by Smith in Great Britain (4). Its corrinoid structure was defined by chemical analy-sis (5) and by x-ray crystallography (6) in 1956. Once it was recognized that the biologically active forms of vitamin B12 were highly photosensitive, Barker et al. (7-9) were able to isolate coenzyme B12 (adenosylcobalamin) from Clostridium tetanomorphum and from liver. A second biologically active form of vitamin B12 was detected in extracts from human plasma by Lindstrand and Stahlberg and proved to be identical with already synthetically prepared methylcobalamin (10, 11). From the very beginning, chromatographic techniques have enabled re-searchers to separate and isolate specific cobalamin compounds from natural substances and preparative mixtures. These techniques keep on contributing to the expansion of our detailed knowledge of cobalamin biosynthesis in micro-organisms and the reaction mechanisms in cobalamin-dependent metabolic path-ways.
