Polymyxin chemical structure

Fig. 3.9 Chemical structures of colistin, polymyxin, rifaximin, rifamycin SV, novobiocin, and tiamulin.

Figure 14.10 Poiymyxin, chemical structures (a) Polymyxin E (colistin) (b) Polymyxin B (Polymyxin B R=FI is polymyxin B1, R=CFl3 is polymyxin B2).

Suzuki T, Hayashi K, Fujikawa K, Tsukamoto K (1965) The chemical structure of polymyxin E the identities of polymyxin El with colistin A and polymyxin E2 with colistin. J Biol Chem 57 226-227... 

Suzuki, T., K. Hayashi, K. Fujikawa, and K. Tsukamoto The chemical structure of polymyxin E The identities of polymyxin E with colistin A and of polymyxin Eg with colistin B. J. Biochem. (Japan) 57, 226 (1965). 

Chemically, colistin is a polypeptide, reported by Suzuki (1 al.. whose major component is colistin A. They pro-pt sed the structure shown below for colistin A. which differs hnm polymyxin B only by the substitution of n-leucine for isphcnylalanine as one of the amino acid fragments in the. jclic portion of the structure. Wilkinson and Lowe have c lTToboraied the structure and have shown that colistin A is iihiiiul with polymyxin Ej. 

Brevin, Brevolin and Edein, three peptide antibiotics with structures yet unknown, are not in clinical use Table 1.4). Tyrothricin consists of a whole group of chemically and biologically closely related individuals, a feature known for the polymyxins, the bacitracins and other peptide-type antibiotics. The tyrothricin group is interesting not only because of its clinical application, but also from a historical viewpoint. Tyrothricin was the second antibiotic found, 10 years after the discovery of penicillin, in a direct search for antibiotic substances. As the first antibiotic of strictly peptide nature, it... 

The polymyxins—The members of the polymyxin group have very similar chemical and physical properties. They are all cyclic basic polypeptides containing characteristic constituents such as a,y-diaminobutyric acid, i,-threonine and a fatty acid. They differ by the presence or absence of the additional amino acids D-leucine, L-leucine, L-isoleucine, n-phenylalanine, D-valine and D-serine, as well as by the nature of the fatty acid Table 1.11). Their molecular weights are aU in the region of 1,200. Although several structural features had been established very early - the exact... 

---