586 



BIOTIN 



the following- set of reactions, which should be amenable to experimental 

 verification.-^ 



O 



±2H 



±211 



HO H 



\ / 



HN NH 



I I 



HC CH 



I I 



H2C. XH(CH5)4COOH 



S 



V. Specificity of Action 



PAUL GYOROY 



Although there is probably only one form of biotin, a lai-<>,-e nvnnber of 

 analogs or isomers are known with some biological activity for animals 

 and especially for microorganisms. They were discussed and tabulated in 

 the section dealing with the chemical specificity of l)iotin and its analogs 

 (p. 558ff). Oleic acid, pimelic acid, and similar compounds, although chem- 

 ically not related to biotin, may spare biotin in some lowei' foi'ms of life. 



The best way of producing V)iotin deficiency in animals is the addition 

 of avidin to the diet. Avidin binds biotin in the intestinal traci andby pre- 

 venting the absorption of biotin causes a progressi\'e deficiency state. This 

 deficiency state may be averted or cured by the addition of biotin in ex- 

 cess to the diet or by the parenteral administration of bioiin or its biologi- 

 cally active analogs. 



Microorganisms possess a definite configurational specificity with re- 

 gard to biotin activity in addition to responding differently to various 

 analogs of biotin and its precursors. Tn general the (^/c.r//'o-rotatory form 

 of biotin and its analogs is the l)iologically acti\'e steroisomei". f.cuconosfoc 

 dextranicum elai is uniciue in that dl forms of oxyl)i()lin and dcsthiobiotin 

 are equal to r/-biotin in allowing maximum growth in aspartate-free fructose 

 medium. In the absence of an v demonstrable time lag it mav be assumed^ 



' V. Whiteside-Carlson, W. K. Slarncs, C. L. Hosiiiio, and \V. \V. Carlson, I'roc. 

 Soc. Exijll. Hi„l. M,<l. 77, :511 (1!)51). 



