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https://hdl.handle.net/2440/123303
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Type: | Journal article |
Title: | Dimeric and trimeric homo- and heteroleptic hydroxamic acid macrocycles formed using mixed-ligand Fe(III)-based metal-templated synthesis |
Author: | Sresutharsan, A. Tieu, W. Richardson-Sanchez, T. Soe, C.Z. Codd, R. |
Citation: | Journal of Inorganic Biochemistry, 2017; 177:344-351 |
Publisher: | Elsevier |
Issue Date: | 2017 |
ISSN: | 0162-0134 1873-3344 |
Statement of Responsibility: | Athavan Sresutharsan, William Tieu, Tomas Richardson-Sanchez, Cho Zin Soe, Rachel Codd |
Abstract: | Macrocyclic hydroxamic acids coordinate Fe(III) with high affinity as part of siderophore-mediated bacterial iron acquisition. Trimeric hydroxamic acid macrocycles, such as desferrioxamine E (DFOE), are prevalent in nature, with fewer dimeric macrocycles identified, including putrebactin (pbH2), avaroferrin (avH2), bisucaberin (bsH2) and alcaligin (alH2). This work used metal-templated synthesis (MTS) to pre-assemble complexes between one equivalent of Fe(III) and two equivalents of 4-((4-aminobutyl)(hydroxy)amino)-4-oxobutanoic acid (BBH) or 4-((5-aminopentyl)(hydroxy)amino)-4-oxobutanoic acid (PBH). Following peptide coupling, the respective Fe(III) complexes of pbH2 or bsH2 were formed, which analysed by LC-MS under acidic pH as [Fe(pb)]+ ([M]+, m/zobs 426.1) or [Fe(bs)]+ ([M]+, m/zobs 454.2). The mixed-ligand 1:1:1 Fe(III):BBH:PBH system furnished [Fe(pb)]+ and [Fe(bs)]+, together with chimeric [Fe(av)]+ ([M]+, m/zobs 440.2). The deviation from the expected 1:2:1 distribution of [Fe(pb)]+:[Fe(av)]+:[Fe(bs)]+ to 1:3.2:1.6 suggested the MTS-mediated formation of dimeric macrocycles could be influenced by steric effects in the pre-complex and/or cavity size, as governed by the monomer. 21-Membered avH2 defined the lower boundary of the optimal architecture. Mixed-ligand MTS between Fe(III):PBH-d4:ret-PBH at 1:1.5:1.5, where ret-PBH=3-(6-amino-N-hydroxyhexanamido)propanoic acid, gave four Fe(III)-loaded trimeric hydroxamic acid macrocycles in a distribution of 1.0:3.0:2.9:1.1 that closely matched the expected distribution 1:3:3:1 for a system without any kinetic and/or thermodynamic bias. Apo-macrocycles pbH2, avH2 and bsH2 were produced upon incubation with diethylenetriaminepentaacetic acid (DTPA) and co-eluted with a biosynthetic mixture of the native macrocycles. The work has demonstrated the utility of single- and mixed-ligand MTS for producing a variety of homo- and heteroleptic dimeric hydroxamic acid macrocycles as Fe(III) complexes and free ligands. |
Keywords: | Hydroxamic Acids Macrocycles Metal-templated synthesis Siderophores Iron(III) |
Description: | Available online 01 August 2017 |
Rights: | © 2017 Elsevier Inc. All rights reserved. |
DOI: | 10.1016/j.jinorgbio.2017.07.033 |
Grant ID: | http://purl.org/au-research/grants/arc/DP140100092 |
Published version: | http://dx.doi.org/10.1016/j.jinorgbio.2017.07.033 |
Appears in Collections: | Aurora harvest 4 Molecular and Biomedical Science publications |
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