Heat-Labile, Avidin-Uncombinable, Species-Specific and Other Vitamers of Biotin

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Abstract
Compounds that act to overcome a given vit. deficiency (in one or another organism, animal or plant) may be termed vitamers (vitameric). Normal urines of man, dog, horse rat, mouse, cow and sheep contain high yeast growth biotin activity (approximately 0.04, 0.08, 0.1, 0.3, 0.5. 0.5 and 1.0 mg. biotin per liter), 20 to 80% of which is in a form unaffected by avidin. This avidin-uncombinable biotin vitamer, called miotin, also occurs in practically all tissues and food-stuffs, is active for yeast but not for Rhizobium trifolii (nor rat or mouse, probably), and is converted by autoclaying at physiological pH''s to another vitamer. tiotin, that is stable to further autoclaving and is also avidin-uncombinable. Neither miotin nor tiotin are the avidin-uncombinable diaminocarboxylic acid derived from biotin (DAC, urea ring opened), for only the latter was converted to avidin-combinable form by phosgene, although all three were by yeast. The CO2 pressure requirement for growth of yeast with DAC is much greater than with biotin, miotin or tiotin, and maximum DAC activity at limiting DAC concentrations requires greater than 0.03% atm. CO2. Biotin and its vitamers may act as a coenzyme of CO2 transplant, either in CO2 utilization or CO2 production. A table of properties of eight known biotin vitamers is provided with respect to species activity (higher animals, lower plants), autoclaving stability (neutral and acid pH''s), avidin combina-bility, and interconvertibility by yeast or phosgene.