88 KARL FOLKERS 



TABLE XIX 



Relationship of the Growth Factor (Strepogenin) Required by Certain 

 Hemolytic Streptococci to Growth Phenomena of Other Bacteria 



Growth factor (Pollack and Lindner, 1943) for L. casei. Source: Peptone 

 Growth factor (Smith, 1943) for strains of 5. lactis. Source: Peptone, yeast 

 Growth factors for L. arabinosus, diphtheria bacillus and propionic acid 

 bacteria (1943). 



Relative Potencies of Strepogenin Concentrates for Bacteria 

 (Sprince and Woolley, 1944) 



Fraction prepared by Recovery activity (%) 



strep. X40 L. casei S. lactis 



It appeared that the chemical nature of strepogenin is that of an 

 amphoteric peptide-like compound, or it is that of a proper combina- 

 tion of amino acids. 



In an effort to learn whether strepogenin was of importance in animal 

 nutrition, Woolley tested the growth response of mice to certain diets. 



TABLE XX 



The Occurrence of Strepogenin in Purified Proteins 



Wright and Skeggs (1944) : Casein > strepogenin-like activity 



Chemical nature of strepogenin : amphoteric peptide-like compound or 



proper combination of amino acids 



Relative strepogenin contents of proteinaceous materials (after trypsin 

 digestion for 20 hours), Sprince and Woolley (1945) 



Material 

 Liver fraction L 

 Crystalline insulin 

 Crystalline trypsinogen 

 Crystalline chymotrypsin 

 Crystalline tobacco mosaic virus, etc. 



Relative strepogenin content 

 I 

 40 



30 

 16 



6 



