Chapter 4 

 BIOTIN 



Page 



I. Nomenclature and Formula 526 



II. Chemistry 527 



A. Isolation 527 



B. Chemical and Physical Properties 531 



C. Constitution 532 



1. Functional Groups 532 



2. The Nature of the Sulfur in Blot in 533 



3. The Side Chain in the Biotin Molecule 535 



4. The Size of the Urea Ring 537 



5. Desthiobiotin 539 



6. The Structure of Biotin 541 



7. a- and (8-Biotins 542 



D. Synthesis of Biotin 544 



E. Synthesis of Biotin Analogs 549 



1. Desthiobiotin 549 



2. Oxybiotin 551 



F. Complex Biotin Compounds 553 



1. Biocytin 553 



2. Other Forms of Bound Biotin 555 



3. Avidiu 555 



G. Specificity 558 



1. Biotin 558 



2. Desthiobiotin 562 



3. Unspecific Stimulatory Precursors and Substitutes 564 



III. Industrial Preparation 572 



IV. Biochemical Systems 575 



A. Enzymes and CoenzjTiies 575 



B. Mechanism of Action 575 



1. Biotin in Aspartic Acid Synthesis 576 



2. Biotin in Carbon Dioxide Fixation and Decarboxylation . . . 577 



3. Biotin in Deamination 582 



4. Biotin in Other Enzjine Systems 584 



5. Summary 585 



V. Specificity of Action 586 



VI. Biogenesis 587 



VII. Estimation 588 



A. Bioassay Using Higher Animals 589 



1. Rat Method 589 



2. Chick Method 593 



B. Microbiological Estimation 593 



VIII. Standardization of Activity 595 



IX. Occurrence in Food 595 



X. Effects of Deficiency 600 



A. Rats and Mice 600 



525 



