Pfizer Handbook of Microbial Metabolites 



340 



The biosynthesis of gramicidin S has been studied. ^^ The 

 conclusions were: (a) The five amino acids of the cyclic de- 

 capeptide pass through a number of intermediates before or 

 during incorporation, (b) Final formation of gramicidin S is a 

 simple reaction not requiring free amino acids which occurs 

 readily in cell-free suspensions, (c) Three peptides were iso- 

 lated containing fragments of the amino acid sequences of the 

 antibiotic. These may or may not have been intermediates. 



It is possible to extract intracellular peptides with suitable 

 solvents. This has been done with mammalian pituitary tis- 

 gyg 16. 17 ^fjj plant seeds^^ and with yeast^" and bacteria.-"' ^^ In 

 all cases cited care was taken to obviate contamination by frag- 

 ments of proteolysis. There is some indication that yields are 

 higher from rapidly growing bacteria than from resting cells. 



The intracellular peptides of the torula yeast studied were 

 found to be predominantly acidic with glutamic acid the princi- 

 pal amino acid. About 40 peptides were purified in adequate 

 quantity to permit hydrolysis and identification of constituent 

 amino acids. These are tabulated below (x indicates an un- 

 identified ninhydrin-positive substance ) : 



TABLE II 

 Some Intracellular Peptides of Torula Yeast 



15 J. M. Barry and Elizabeth Ishihara, Nature 181 1274 (1958). 



I*' T. Winnick, R. E. Winnick, R. Acher and C. Fromageot, Biochim. 

 et Biophys. Acta 18 488 (1955). 



" L. K. Ramachandran and T. Winnick, ibid. 23 533 (1957). 



1^ H. Borriss and G. Schneider, Naturwissenschaften 42 103 

 (1955). 



"F. Turba and H. Esser, Biochem. Z. 327 93 (1956). 



2° G. E. Connell and R. W. Watson, Biochim. et Biophys. Acta 24 

 226 (1957). 



21 R. B. Roberts, P. H. Abelson, D. C. Cowie, E. T. Bolton and R. J. 

 Britten, "Studies of Biosynthesis in E. coli," Carnegie Institute, Wash- 

 ington, D. €., 1955. 



