海藻中类金属硫蛋白的分离表征及对Zn,Cu的诱导响应

以海带为试验载体,利用葡聚糖凝胶柱,建立了海藻中类金属硫蛋白(MT-like)的分离、提取纯化技术;采用紫外分光光度法比对类金属硫蛋白与兔肝Zn-MTs的紫外吸收,并用凝胶电泳法对其分子量范围进行表征,同时利用质谱法精确测定其分子量;并在ZnCl2,CuCl2,ZnCl2+CuCl2不同条件下胁迫培养藻体,考察了海带对重金属的富集能力,探索藻体中MT-like对Zn及Cu元素的诱导响应。结果显示,MT-like与兔肝Zn-MTs在294 nm处有相似的紫外吸收峰,在SDS-PAGE凝胶电泳图上显像类似,分子量范围相近,经电喷雾离子源质谱测定该蛋白质的分子量约为6.5 ku。另外,海带对重金属的富集能力较强,对Zn元素的富集能力明显高于Cu元素;Zn2+对藻体MT-like的产生有促进作用,而MT-like随着Cu2+诱导时间的增长先增加后降低,且Cu2+对Zn2+诱导存在拮抗效应。     

Resistance of Cu(Aβ4–16) to Copper Capture by Metallothionein‐3 Supports a Function for the Aβ4–42 Peptide as a Synaptic CuII Scavenger

Aβ4‐42 is a major species of Aβ peptide in the brains of both healthy individuals and those affected by Alzheimer's disease. It has recently been demonstrated to bind Cu^II with an affinity approximately 3000 times higher than the commonly studied Aβ1‐42 and Aβ1‐40 peptides, which are implicated in the pathogenesis of Alzheimer's disease. Metallothionein‐3, a protein considered to orchestrate copper and zinc metabolism in the brain and provide antioxidant protection, was shown to extract Cu^II from Aβ1‐40 when acting in its native Zn₇MT‐3 form. This reaction is assumed to underlie the neuroprotective effect of Zn₇MT‐3 against Aβ toxicity. In this work, we used the truncated model peptides Aβ1‐16 and Aβ4‐16 to demonstrate that the high‐affinity Cu^II complex of Aβ4‐16 is resistant to Zn₇MT‐3 reactivity. This indicates that the analogous complex of the full‐length peptide Cu(Aβ4‐42) will not yield copper to MT‐3 in the brain, thus supporting the concept of a physiological role for Aβ4‐42 as a Cu^II scavenger in the synaptic cleft.     

Metallothionein Induction by Cd(II) and Zn(II)

Blood may contain high proportion of the toxic and essential metals.Blood is responsiblefor the transport of ion of such metals.The organs such as the kidney,liver and placentaare exposed to a large proportion of the metals which enter the blood and may b…     

Qualitative characterization of biomolecular zinc complexes by collisionally induced dissociation

Nanospray and collisionally induced dissociation (CID) on a quadrupole/time-of-flight mass spectrometer were used to examine the complexes formed between the zinc ion binding protein metallothionein and a series of peptides related to glutathione. The objective of the study was to determine if CID could be used to distinguish complexes that are stabilized by co-chelation of a zinc ion from non-covalent complexes that were formed in some other way. Differences in the collision energy required for dissociation and, more importantly, differences in the distribution of zinc ions between the pairs of dissociation products suggest that mass spectrometry can provide qualitative information about the bimolecular chelation of metal ions. The potential application to zinc chelates is particularly important, since biological chelates do not provide signals directly detectable by NMR, M?ssbauer or other spectroscopies. The observations reported here also allowed a molecular mechanism to be proposed to explain the differences observed by others in the physiological interactions of reduced and oxidized glutathione with metallothionein.     

三种金属硫蛋白聚合物静电效应的研究

考察了三种金属硫蛋白(大鼠金属硫蛋白亚型II,兔肝金属硫蛋白亚型I和兔肝金属硫蛋白亚型II)的单体、二聚体和三聚体在pH为5.6-8.5和10.6两种缓冲条件下的静电势分布。其中大鼠金属硫蛋白亚型II的结构直接来自于晶体数据,兔肝金属硫蛋白亚型I和II的结构则通过同源蛋白模型搭建。三种金属硫蛋白的静电势通过有限差分方法求解Poisson-Boltzmann方程得到。对于三种金属硫蛋白的二聚体,pH为5.6-8.5时,单体和单体之间的静电势分布具有明显的互补性;但pH≥10.6时,这种互补性会大大削弱。对于三种金属硫蛋白的三聚体,单体和二聚体之间主要表现为静电排斥,而且pH在10.6下的静电排斥力明显强于pH为5.6-8.5时的静电排斥。     

鼠脑GIF的提取及其与脱锌碳酸酐酶的供锌动力学研究

本文从大鼠脑组织中提取了GIF ,并研究了它与　apo CA之间的锌转移反应 ,计算出不同温度下　GIF的供锌速率 ,并进一步求出了供锌过程的热力学常数。