ISSN:
1572-8773
Keywords:
azoverdin
;
Azomonas macrocytogenes
;
15N NMR
;
siderophore
;
iron transport
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Two major azoverdins were isolated from the cultures of Azomonas macrocytogenes ATCC 12334 grown in irondeficient medium. Their structures have been established using fast atom bombardment-mass spectroscopy, homonuclear and heteronuclear two-dimensional 15N, 13C and 1H NMR, and circular dichroism techniques. These siderophores are chromopeptides possessing at the N-terminal end of their peptide chain the chromophore derived from 2,3-diamino-6,7-dihydroxyquinoline common to pyoverdins. The linear peptide chain (l)-Hse-(d)-AcOHOrn-(d)-Ser-(l)-AcOHOrn-(d)-Hse-(l)-CTHPMD has at its C-terminal end a new natural amino acid which is the result of the condensation of 1 mol of homoserine and 1 mol of 2,4-diaminobutyric acid forming a cyclic amidine belonging to the tetrahydropyrimidine family: 2-homoseryl-4-carboxyl-3,4,5,6-tetrahydropyrimidine. The azoverdins differ only by a substitutent bound to the nitrogen on C-3 of the chromophore: azoverdin, the most abundant one, possesses a succinamide moiety, whereas azoverdin A bears a succinic acid moiety. 15N-labelled azoverdin afforded readily, after the complete assignment of the 15N spectrum of the siderophore, a sequence determination of the peptidic part of the molecule and gave evidence for the presence of two tetrahydropyrimidine groups on the molecule: one on the chromophore and the second at the C-terminal end of the siderophore.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00144615
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