NEW PYOVERDIN TYPE SIDEROPHORES FROM PSEUDOMONAS-FLUORESCENS

The structure of four new pyoverdins (Pf 12-I A, -I B und II B) isolated from the culture medium of Pseudomonas fluorescens 12 was elucidated by combination of spectroscopic methods and degradation reactions. The pyoverdins comprise (1S)-5-amino-2,3-dihydro-8,9-dihydroxy-1H-pyrimido[1,2-a]quinoline-1-carboxylic acid whose amino group carries a 3-carboxypropanoyl- (I A), succinamoyl- (II A), 4-carboxy-4-oxobutanoyl- (I B) or L-4-amino-4-carboxybutanoyl-residue (II B) and whose carboxyl group is bound amidically to the N-terminus of D-Ser-L-Lys-Gly-L-(N5-CHO-N5-OH)Orn-D-Ser-L-Ser-Gly-L-L activated ys-D-(N5-CHO-N5-OH)Orn-L-Glu-L-Ser. According to the short-hand-nomenclature suggested in [2, 3] the pyoverdins may be described as pyoverdin-Q-sKGO'sSGK*o'ES*-SUC (IA), pyoverdin-Q-sKGO'sSGK*o'ES*-SUCA (IIA), pyoverdin-Q-sKGO'sSGK*o'ES*-KGL (I B) and pyoverdin-Q-sKGO'sSGK*o'ES*-GLU (II B). The pyoverdins described here possess the most complex structure encountered so far as their peptide part comprises eleven amino acids and the cyclo-tetrapeptide substructure. In addition, they are of special interest as for the first time glutamic acid could be identified as a chromophore side chain which is the key compound for the citric acid cycle to which belong all dicarboxylic acids found so far in pyoverdins.