Abstract
1. The pH optima for the incorporation of 14C-labelled amino acids into gramicidin S by an 11000g cell-free extract from Bacillus brevis have been determined. The pH optima for leucine, proline, phenylalanine, ornithine and valine were 7·5–7·7, 7·5–7·7, 7·7–7·9, 7·7–7·9 and 8·0–8·2 respectively. Hence the greatest difference in pH optima existed between leucine and valine, where it was 0·5pH unit. 2. The 11000g cell-free extract incorporated into gramicidin S only the l-isomers of valine, proline and ornithine. However, both isomers of leucine are utilized and the experiments indicate that a leucine racemase exists in the 11000g cell-free extract. With phenylalanine the l-isomer is utilized much more effectively than the d-isomer. This is noteworthy since it is the d-isomer that occurs in gramicidin S. The experiments indicate that conversion of the l-isomer into the d-form takes place at a stage beyond that of the free amino acid.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- BERG T. L., FROHOLM L. O., LALAND S. G. THE BIOSYNTHESIS OF GRAMICIDIN S IN A CELL-FREE SYSTEM. Biochem J. 1965 Jul;96:43–52. doi: 10.1042/bj0960043. [DOI] [PMC free article] [PubMed] [Google Scholar]
- EIKHOM T. S., JONSEN J., LALAND S., REFSVIK T. STUDIES ON THE BIOSYNTHESIS OF GRAMICIDIN S IN WHOLE CELLS OF BACILLUS BREVIS. Biochim Biophys Acta. 1964 Apr 27;80:648–654. doi: 10.1016/0926-6550(64)90309-3. [DOI] [PubMed] [Google Scholar]
- KATZ E., WISE M., WEISSBACH H. ACTINOMYCIN BIOSYNTHESIS. DIFFERENTIAL EFFECT OF CHLORAMPHENICOL ON PROTEIN AND PEPTIDE ANTIBIOTIC SYNTHESIS. J Biol Chem. 1965 Jul;240:3071–3078. [PubMed] [Google Scholar]
- Spaeren U., Froholm L. O., Laland S. G. Further studies on the biosynthesis of gramicidin S and proteins in a cell-free system from Bacillus brevis. Biochem J. 1967 Feb;102(2):586–592. doi: 10.1042/bj1020586. [DOI] [PMC free article] [PubMed] [Google Scholar]