Countercurrent distribution gramicidins

Gramicidin A (a pentadecapeptite from Bacillus brevis) [11029-61-1]. Purified by countercurrent distribution from C6H6-CHCI3, MeOH-H20 (15 15 23 7) with 5000 tubes. Fractions were examined by UV (280nm) of small aliquots. Separation from Gramicidin C and other material occurred after 999 transfers. [Gross and Witkop Biochemistry 4 2495 1965] Bauer et al. Biochemistry 11 3266 1 972]. Purified finally by... 

Partial" Purification of Commercial Gramicidin hy Countercurrent Distribution and Cleavage by N-Bromoacetamide... 

Fig.l. Countercurrent distribution of gramicidin, showing at least four components to be present. 

More recently we have taken up the study of the purity of crystalline gramicidin by the method of countercurrent distribution (9). It did not prove to be a single substance, as is shown by the distribution pattern in Figure 1. At least four gramicidins are revealed by this pattern, one... 

In 1939 Dubos reported the isolation of the antibiotic tyrothricin from culture filtrates of strains of Bacillus brevis > < He and his co-workers soon succeeded in separating tyrothricin with organic solvents into two crystalline compounds, the neutral gramicidin and the basic tyrocidine (formerly called graminic acid and gramidinic acid). Tyrothricin is thus a term for the partially purified antibiotic obtained from the culture fluids of Bacillus brevis. It contains on the average a mixture of 20 per cent gramicidin and 80 per cent tyrocidine. Besides these, at least three further polypeptides have been found by countercurrent distribution of tyrothricin. 

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