COORDINATIVE BINDING OF DIVALENT CATIONS WITH LIGANDS RELATED TO BACTERIAL SPORES - EQUILIBRIUM STUDIES
COORDINATIVE BINDING OF DIVALENT CATIONS WITH LIGANDS RELATED TO BACTERIAL SPORES - EQUILIBRIUM STUDIES
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DOI：
10.1016/s0006-3495(71)86229-x
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发表时间：
1971-01-01
影响因子：
3.4
通讯作者：
GRECZ, N
中科院分区：
文献类型：
--
作者：
CHUNG, L;RAJAN, KS;GRECZ, N
人们一再假设，细菌孢子的高耐热性是由于孢子内部的生物聚合物通过由配体与二价金属离子的配位配合物组成的保护水泥的固体沉积而稳定。在温度和离子强度（t = 25.0°C; μ = 1.0 KNO3）条件下，通过电位平衡测量，本文给出了一些与孢子有关的配体的金属结合特性的数据，这些数据与作者先前报道的相同，以便通过使用可比数据促进相关性。本研究研究的配体包括2,6-吡啶二羧酸（DPA）、α， α -二氨基苯甲酸、d -谷氨酸和d -丙氨酸，它们与金属离子的比例为1:1，已知它们在孢子的耐热性中起作用。测定了这些孢子配体与Ca（II）、Mg（II）、Cu（II）、Ni（II）、Zn（II）、Co（II）、Mn（II）等金属离子螯合物的稳定性常数。总的来说，DPA的金属螯合物表现出最大的稳定性。在综合考虑稳定性数据、已知配体构型和金属离子配位要求的基础上，提出了指示孢子配体与金属离子配位结合的可能结构。除Ca（II）外，其余金属螯合物在pH 7 ~ 8.5范围内均发生固相水解和分离。Ca（II）螯合物相对较高的水解稳定性和DPA对金属离子的高亲和力似乎具有生物学意义，因为这两种孢子成分更广泛地与细菌孢子的耐热性相关。
It has been repeatedly postulated that the high heat resistance of bacterial spores is due to stabilization of biopolymers in the spore interior by a solid deposit of protective cement consisting of coordination complexes of ligands with divalent metal ions. This report presents data on metal-binding characteristics of some of the ligands related to spores as determined by means of potentiometric equilibrium measurements under conditions of temperature and ionic strength (t = 25.0°C; μ = 1.0 KNO3) identical with those reported earlier by the authors in order to facilitate correlation by using comparable data. The spore ligands investigated in this study included 2,6-pyridinedicarboxylic acid (DPA), α,ɛ-diaminopimelic acid, D-glutamic acid, and D-alanine in a ratio of 1:1 with metal ions which are known to play a role in heat resistance of spores. Stability constants of the chelates of these spore ligands with metal ions such as Ca(II), Mg(II), Cu(II), Ni(II), Zn(II), Co(II), and Mn(II) have been determined. In general the metal chelates of DPA exhibited the greatest stability. On the basis of a consideration of the stability data together with the known configurations of the ligand and the coordination requirements of the metal ions, possible structures indicating the coordinate binding of the spore ligands with the metal ions are presented. All the metal chelates except those of Ca(II) were found to undergo hydrolysis and separation of solid phase in the pH range 7–8.5. The relatively greater hydrolytic stability of Ca(II) chelates and the high affinity of DPA for metal ions appear to be of biological significance insofar as these two spore components are more widely associated with the heat resistance of bacterial spores.