375 



Polypeptides and Related Compounds 



Commercial polymyxin is essentially polymyxin B sul- 

 fate, a white powder, m.p. 228-232° (dec.), Whr' -45° 

 (c 0.1). The empirical formula of the free base is 

 CseH.tc.gsOjsNie. 



G. C. Ainsworth, A. M. Brown and G. Brownlee, Nature 160 

 263 (1947). (Isolation) 



George Brownlee, Ann. N. Y. Acad. Sci. 51 875 (1949). 

 (Polymyxin A) 



P. H. Bell, J. F. Bone, J. P. English, C. E. Fellows, K. S. 

 Howard, M. M. Rogers, R. G. Shepherd and R. Winterbottom, 

 ibid. 51 897 (1949). (Degradations, identification of amino 

 acids) 



Tudor S. G. Jones, ibid. 51 909 (1949). (Separations, deg- 

 radations, identification of amino acids) 



J. R. Catch, Tudor S. G. Jones and S. Wilkinson, ibid. 51 

 917 (1949). 



P. P. Regna, I. A. Solomons, B. K. Forscher and A. E. 

 Timreck, /. Clin. Invest. 28 1022 (1949). (Purification of B) 



Werner Hausmann and Lyman C. Craig, J. Am. Chem. Soc. 

 76 4892 (1954). (Resolution of B into two parts) 



Werner Hausmann, ibid. 78 3663 (1956). (Proposal of de- 

 tailed cyclic structures) 



Gerard Biserte and Michel Dautrevaux, Bull. soc. chim. biol. 

 39 795 (1957). (Structure) 



Gramicidins. 



A mixture of polypeptides produced by Bacillus brevis 

 and originally called tyrothricin was separated into two 

 groups, the tyrocidines (about 80 "^r ) and the gramicidins 

 (about 20%). Each of these groups has been fraction- 

 ated further into pure polypeptides. 



The original gramicidin consisted of a mixture of three 

 closely related neutral polypeptides. It was assigned an 

 average empirical formula of C]4SjH2io02(iN3o, colorless 

 platelets, m.p. 228-231°, [aW +3°. 



D-Leucine 



L-Trypotophon. 



l-Alanine 



DL- Valine 



Glycine 



Phenylalanine. 

 Tyrosine 



