381 Polypeptides and Related Compounds 



Bacillus brevis 



T. P. King and L. C. Craig. /. Am. Chcm. Soc. 77 6627 

 (1955). (Final structure) 



Actinomycins. 



The nomenclature of the actinomycins is confused be- 

 cause they occur in difficulty separable complex mixtures, 

 several different research groups have investigated them, 

 and, even when pure, one substance cannot be compared 

 with another by techniques as simple as a mixed melting 

 point. This problem has been discussed by Brockmann 

 in a review of the actinomycins. 



L. Zechmeister (editor), "Fortschritte der Chemie organis- 

 cher NaturstofFe" XVIII, Hans Brockmann, The actinomycins. 

 Springer Verlag, Vienna, 1960. 



At first actinomycins A, B and C were isolated, but later 

 these were found to be mixtures. As such complexes 

 were resolved by paper chromatography, Arabic numeral 

 subscripts were attached to the capital Roman letter in 

 order of appearance on the developed chromatogram, the 

 origin on the paper being zero (e.g., Ci, Co, C3). When 

 some of the separated actinomycins were resolved even 

 further, a further subdivision in nomenclature was re- 

 quired; so a lower case Roman letter was attached to give, 

 ^■9-, Coj, which appeared between Co and C3. When the 

 Xo complex at the origin was resolved, a slightly different 

 system was used, Greek letters being attached to the 

 Arabic numeral subscript, e.g., Xo^ was less polar than X,,;,. 



Few series are complete because often names have been 

 eliminated due to duplication, further resolution, etc. 

 Thus, a complex designated I was resolved into Ii and L, 

 but these later were shown to be the same as Cj and C2 

 and the I names eliminated. 



Still this method of nomenclature does have a ration- 

 ale, although it may not be readily apparent, and it is used 

 in Germany and in Switzerland. 



Other groups continue to refer to various complexes as 

 A, B or D types. These consist essentially of various ratios 

 of actinomycin Xo and its reduction product, actinomycin 

 Ci, actinomycin D being nearly pure Cj. 



The E and F series arose when it was discovered that 

 addition of certain amino acids to the medium in large 

 amounts caused displacement of certain other amino 

 acids in the peptide side-chains, thus creating new "bio- 

 synthetic" actinomycins. 



