The structures of the amphiphilic peptide antibiotics herbicolin A and B were determined by application of physical methods, chemical degradation, and partial syntheses. Herbicolin Herbicolins A and B were isolated from a bacterial strain A 11 1, identical with Erwinia herbicola, in a screening program for antifungal agents. Both antibiotics are highly active against yeasts and filamentous fungi but not active against bacteria 'a2).The herbicolins show minimal inhibition concentrations (MIC) of 0.2-0.6 pg/ml in serial dilution tests against Trichophyton rubrum, Epidermophylon ,floccosum, and Microsporum canis3'. Herbicolin A inhibits the growth of the sterol-requiring Mycoplasma, Ureaplasma,

No abstract

The sequence of the potential-dependent membrane pore-forming polypeptide antibiotic suzukacillin A was determined by a combination of trifluoroacetolytic cleavage, preparative isolation of fragments, and analysis by gas chromatography -mass spectrometry, fielddesorption and fast-atom bombardment mass spectrometry. Suzukacillin A is a microhetero- Suzukacillin A is a peptide antibiotic produced by the fungus Trichoderrna viride1-3) which imparts potential dependent ion-conducting pore formation in lipid bilayer membranes4). These membrane-modifying properties are of particular interest because of their close resemblance to those of alamethicin and analogues which have been explained by the flip-flop gating model5). For further information we refer to recently published articles6-lo).Sequencing by using GC-MS of trifluoroacetyfated peptide methyl esters from a partial hydrolysate revealed a preliminary sequence ll). However, the problem of amino acid exchange in certain positions of the sequence could not be solved at that time. Therefore we report in the following full details of the sequencing of suzukacillin A 0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1985

Suzukacillin A is a potential-dependent membrane pore-forming polypeptide antibiotic exhibiting similar properties as alamethicin in biophysical1.2) and biological3-6) experiments. The essential a-helical part of these polypeptides with its high dipole moment is responsible for potential-dependent pore formation in black lipid membranes as described by the flip-flop gating model7). On the other hand the polarity and size of the C-and N-termini determine specific characteristics such as medium pore size and stability of pore statesa.9). Thus the exact knowledge of structure/activity relations contributes considerably to a better understanding of the ionconduction properties of these linear amphiphilic polypeptides.A preliminary sequence based solely on GC-MS studies of partial fragments was published 1976 by our groups'). As alamethicin'O.'') and trichotoxin A40'2-'4) the eicosapeptide suzukacillin A belongs to the longest peptide antibiotics known and shows a characteristic natural microheterogeneity in its amino acid composition. Because of several ambiguities in the former instrumental sequencing') it was necessary to isolate and 0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1985

Pseudomonas fluorescens, Proteus vulgaris, and Serratia marcescens, members of the microflora of soil and waste water, attacked methionine in the presence of glucose. The sulfur of methionine was released as methane thiol, dimethyl sulfide and dim ethyl disulfide. The volatile sulfur com pounds were qualitatively and quantitatively investigated by gas chromatography. Dimethyl disulfide was formed of methane thiol by various bacteria to a different extent. Growing in the presence of oxygen, S. marcescens oxidized most of the m ethane thiol to dim ethyl disulfide. In the presence of glucose. P. fluorescens dissimilated m ethionine with production of m ethane thiol and dimethyl disulfide. The dissimilation was stimulated with decreasing glucose concentration