Rhizobium meliloti, rhizobactin

Rhizobactin (40) is the siderophore of Rhizobium meliloti 328). It contains one ot-hydroxycarboxylic acid and two ot-amino acid units as probable binding sites for Fe ". Acid hydrolysis yields inter alia L-malic acid. The stereochemistry of the other two chiral centers is not known. 

Rhizobactin 1021 (Fig. 15, 56) (for rhizobactin, see diaminoalkane-based siderophores, Sect. 3.1) from Rhizobium meliloti (281), contains an acetyl and an ( )-decenoyl group. Its Fe " complex in aqueous solution is A-configured and forms an equilibrium between a monomeric and a dimeric form that can be separated by chromatography. A synthesis is described (404). 

Persmark M, Pittman P, Buyer JS, Schwyn B, Gill PR Jr, Neilands JB (1993) Isolation and Structure of Rhizobactin 1021, a Siderophore from the Alfalfa Symbiont Rhizobium meliloti 1021. J Am Chem Soc 115 3950... 

Smith MJ, Shoolery JN, Schwyn B, Holden I, Neilands JB (1985) Rhizobactin, a Structurally Novel Siderophore from Rhizobium meliloti. J Am Chem Soc 107 1739... 

Another excellent example of the application of NMR techniques in the structure determination of natural products is the structural resolution of rhizobactin, a siderophore isolated from Rhizobium meliloti (354). The proton homonuclear 2D-correlated spectrum revealed the four separate coupled units, whereas the heteronuclear 2D-correlated spectrum established the assignments (Fig. 2.43). Together, these spectra revealed that rhizobactin is composed of one unit each of ethylene diamine, alanine, lysine, and L-malic acid. The sequencing of... 

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