The amino acid sequence in bacitracin A

The Chemistry of Proteins and Peptides

“…The struc ture suggested by much painstaking work, mainly of two laboratories, con tains one peptide linkage with the E-amino group of lysine, and another in volving the ,),-carboxyl of aspartic acid. There also is evidence for an-SH group, "masked" through closure of a thiazoline ring between a cysteine and an adjacent isoleucine residue, a ring which strongly affects the reactivity of the amino group, and enables it to form a bond with a phenylalanine residue [Weisinger, Hausmann & Craig (183, 184, 242); Lockhart & Abra ham (243)]. The nature of this bond is almost beyond conjecture.…”

The N-terminal and sulphur-containing residues of bacitracin A

“…The present paper describes attempts to obtain more precise information about this structure by using reagents for the free amino groups of peptides and by further study of the products of hydrogenolysis with Raney nickel. Some of the results have already been reported in outline (Lockhart et al 1954;Lockhart & Abraham, 1954b). Other interesting evidence about this part of the molecule has been mentioned by Hausmann, Weisiger & Craig (1955b), who have concluded that a thiazole derivative is formed when bacitracin A is converted into bacitracin F by oxidation in air.…”

“…Lys. All these peptides have been found to be particularly resistant to further hydrolysis (Hausmann et al 1955b;Lockhart & Abraham, 1954b). It would therefore be understandable if the yield of isoleucine were less than theoretical.…”

“…The latter is presumably adjacent to the potential cysteine residue, since Lockhart & Abraham (1954b) reported that isoleucine residues in two other positions in the molecule remained intact in the deaminated product.…”

Synthesis of antibiotics by enzymes from altered growth conditions by Bacillus licheniformis

“…1), the major component, is highly active as an antibiotic, whereas bacitracin F is inactive. Bacitracin B appear to have the same structure as A with replacement of ring isoleucine by valine [3]. The structure of other bacitracins is not known, but D and E yield also valine and C yields glycine as well [2].…”