373 Polype ptides and Related Compounds 



U. Sumiki and K. Miyao, /. Agr. Chem. Soc. Japan 26 27 

 (1952). 



Idem., Bull. Agr. Chem. Soc. (Japan) 19 86 (1955). 

 Kohei Miyao, ibid. 24 23 (1960). 



779 Polypeptin (formerly called circulin, but not identical with the 

 polypeptide now known as circuHn), C^gHooOiaN,.., color- 

 less crystals, m.p. 176°, [a],,-" (Sulfate) -93.3° (c 3.0 in 

 70% isopropyl alcohol). 



A basic polypeptide, containing: three a,y-diaminobu- 

 tyric acids, one L-threonine, one D-vaHne, one L-isoleucine, 

 two L-leucines and one D-phenylalanine. 



Bacillus krzemieniewski, a B. circulans mucoid variant 



Stacey F. Howell, /. Biol. Chem. 186 863 (1950). 



Werner Hausmann and Lyman C. Craig, ibid. 198 405 

 (1952). 



Polymyxins: 



'80 Polymyxin A (Aerosporin) 



'81 Polymyxin Bi 



'82 Polymyxin B, 



'83 Polymyxin C 



'84 Polymyxin D 



'85 Polymyxin E 



A complex of related polypeptides produced by Bacillus 

 polymyxa. Initially five components, A, B, C, D and E 

 were separated. Then B was resolved into two compo- 

 nents Bi and B^, differing only in the fatty acid moiety. 

 All polymyxins contain L-a, y-diaminobutyric acid and 

 L-threonine. All but B^ apparently contain d-6-methyloc- 

 tanoic acid, and it contains a C-8 acid instead. Poly- 

 myxin A has been reported to contain D-leucine but no 

 phenylalanine. It is also known as aerosporin because it 

 is produced by Bacillus aerosporus. Polymyxin C con- 

 tains phenylalanine but no leucine. Polymyxin D con- 

 tains leucine but no phenylalanine, and it also has been 

 reported to contain D-serine. Polymyxin E has the same 

 quahtative composition as A, but is distinct. 



Two alternative structures have been suggested for 

 polymyxin Bj as the result of degradative studies. These 

 structures are shown here, the amino acids being abbrevi- 

 ated in the following manner: 



