Departamento de Química Física e E. Q. I, Facultad de Ciencias, Universidad de La Coruña, La Coruña, Spain.
Metallomics. 2011 May 1;3(5):521-8. doi: 10.1039/c0mt00071j. Epub 2011 Apr 15.
The bacterial fish pathogen Vibrio anguillarum serotype O2 strain RV22 produces the mono catecholate siderophore Vanchrobactin (Vb) under conditions of iron deficiency. Vb contains two potential bidentate coordination sites: catecholate and salicylate groups. The iron(III) coordination properties of Vb is investigated in aqueous solutions using spectrophotometric and potentiometric methods. The stepwise equilibrium constants (log K) for successive addition of Vb dianion to a ferric ion are 19.9; 13.3, and 9.5, respectively, for an overall association constant of 42.7. Based on the previous results, we estimated the equilibrium concentration of free iron(III) under physiological conditions for pH 7.4 solution containing 10(-6) M total iron and 10(-5) M total Vb as pFe = 20 (=-log[Fe(3+)]). The Vb model compounds catechol (Cat) and 2,4-dihydroxy-N-(2-hydroxyethyl)benzamide (Dhb) have also been examined, and the obtained results show that the interaction of the whole system of Vb that contains the ferric-chelating groups of both Dhb and Cat, is synergically greater than the separate parts; i.e. Vb is the best chelating agent either in acid or basic media. In summary, bacteria employing Vb-mediated iron transport thus are able to compete effectively for iron with other microorganisms within which they live.
鱼类病原菌鳗弧菌 O2 血清型 RV22 在缺铁条件下产生单儿茶酚载体铁载体 Vanchrobactin (Vb)。Vb 含有两个潜在的双齿配位位点：儿茶酚和水杨酸基团。本文使用分光光度法和电位法研究了 Vb 在水溶液中的铁（III）配位性质。Vb 二价阴离子连续与铁（III）离子加成的分步平衡常数（log K）分别为 19.9、13.3 和 9.5，总缔合常数为 42.7。基于先前的结果，我们估计了在 pH 7.4 的生理条件下，含有 10(-6) M 总铁和 10(-5) M 总 Vb 的溶液中游离铁（III）的平衡浓度为 pFe = 20（=-log[Fe(3+)]）。还研究了 Vb 的模型化合物儿茶酚 (Cat) 和 2,4-二羟基-N-(2-羟乙基)苯甲酰胺 (Dhb)，得到的结果表明，含有 Dhb 和 Cat 的铁螯合基团的整个 Vb 系统的相互作用协同作用大于单独部分；即 Vb 是在酸性或碱性介质中最好的螯合剂。总之，能够通过 Vb 介导的铁运输的细菌因此能够有效地与它们生活的其他微生物竞争铁。
