双纳米和皮科莫尔 Zn(II) 结合性质的金属氨酸
1Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, Galveston, Texas 77555, USA.
Journal of the American Chemical Society
|August 19, 2007
概括
金属氨酸与不同亲和度的离子结合,调节细胞中的可用性. 胺蛋白 (thionein) 控制的释放,影响醇的反应性和生物过程.
科学领域:
- 生物化学 生物化学
- 金属蛋白化学 金属蛋白化学
- 细胞恒常 细胞恒常
背景情况:
- 人类金属氨酸含有7个Zn(II) 离子,在其Zn(3) S(9) 和Zn(4) S(11) 集群中的四酸盐协调环境中.
- 金属氨酸在细胞缓冲和排毒中发挥着至关重要的作用.
研究的目的:
- 为了研究Zn(II) 离子与氨酸 (apoprotein) 和金属氨酸的结合亲和力.
- 阐明金属氨酸和氨酸在调节细胞中自由的度和醇反应性的作用.
主要方法:
- 使用光合剂 (FluoZin-3和RhodZin-3) 分析Zn(II) 与氨酸的关联以及与金属氨酸的解离.
- 确定Zn(II) 的结合亲缘关系 (显而易见的log K) 和不同Zn(II) 的结合物种 (Zn(4) T到Zn(7) T) 的特征.
主要成果:
- 结合金属氨酸的Zn(II) 呈现至少三种类型的位点,其亲和度不同四个数量级.
- 四个Zn(II) 离子是紧密结合的 (log K ≈ 11.8),而一个是弱结合的 (log K ≈ 7.7),使金属氨酸能够作为捐赠体.
- 在细胞度上占主导的物种是Zn(5) T和Zn(6) T (log K ≈10). 氨酸调节自由Zn (II) 水平,影响醇氧化速率.
结论:
- 金属氨酸的独特的Zn(II) 结合亲缘关系使其能够作为一种强有力的化剂和捐赠剂.
- 氨酸与金属氨酸的比率极大地控制了自由Zn (pZn) 的水平,符合细胞的要求.
- 金属氨酸和氨酸的分子结构和氧化还原化学决定了Zn (II) 适用于重要生物过程的可用性.
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