Pfizer Handbook of Microbial Metabolites 120 



acid, quite evidently acetate-derived, in conjugation with one or 

 more sugar-like moieties. These sugars are uncommon ones, 

 and one of them is usually an amino-sugar, desosamine being 

 particularly prevalent so far. Several of the incompletely char- 

 acterized macrolides, especially those of the polyene type, have 

 been reported to contain no nitrogen, however. Among these 

 are lagosin, fungichromin, A-246, miamycin and filipin. One 

 macrolide, celesticetin,* contains sulfur. Lankamycin also con- 

 tains no nitrogen. 



Of all the macroHdes the biosynthesis of erythromycin has 

 been investigated most thoroughly. One of the questions to be 

 answered was whether the erythronolide moiety is derived from 

 acetate or from propionate. A labeling and degradation study 

 wdth C^*-containing precursors has shown that propionate or its 

 biological equivalent is the true precursor.^ Propionate-C-1 was 

 incorporated only into the "methylene" carbon atoms, while 

 propionate C-2 was incorporated largely into the tertiary carbon 

 atoms and not at all into the carbon-bound methyl groups. Ad- 

 ditional evidence against the acetate hypothesis was the fact 

 that C^Mabeled formate or C^*-methyl methionine did not label 

 the terminal three carbon atom subunit of erythronolide. 



A previous study* had shown that C"-l-labeled propionate 

 caused labehng of erythronolide, but not of the sugars desosa- 

 mine and cladinose. The reverse was true when the labeled 

 precursor was C'*-methyl methionine.^ 



Other evidence which has been published suggests or is con- 

 sistent with derivation of erythronolide from propionate." 



A notice has been pubhshed that a labehng study on the 

 biogenesis of erythromycin is in progress with the use of pro- 

 pionic acid-l-C"-H^' 



It remains to be seen whether or not some of the less highly 



^ John W. Corcoran, Toshi Kaneda and John C. Butte, /. Biol. 

 Chem. 235 pc29 (1960). 



* Z. Vanek, J. Majer, A. Babicky, J. Liebster, K. Veres and L. 

 Dolezilova, Abstr. IVth Intern. Congr. Biochem., Vienna, 1958; cf. 

 Angew. Chem. 71 40 (1959). 



^ Z. Vanek, J. Majer, J. Liebster, K. Veres and L. Dolezilova, 

 Symposium on Antibiotics, Prague, 1959. 



^ V. Musilek and V. Sevcik, Naturwissenschaften 45 86 215 (1958); 

 idem.. Symposium on Antibiotics, Prague, 1959. 



^ H. Grisebach, H. Achenbach and U. C. Grisebach, Naturwissen- 

 schaften 47 206 (1960). 



* See entry 923 for non-macrolide structure. 



