PURIFICATION AND PRIMARY STRUCTURE OF SNAIL METALLOTHIONEIN - SIMILARITY OF THE N-TERMINAL SEQUENCE WITH HISTONES H4 AND H2A
PURIFICATION AND PRIMARY STRUCTURE OF SNAIL METALLOTHIONEIN - SIMILARITY OF THE N-TERMINAL SEQUENCE WITH HISTONES H4 AND H2A
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DOI：
10.1111/j.1432-1033.1993.tb18193.x
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发表时间：
1993-09-15
期刊：
影响因子：
--
通讯作者：
KAGI, JHR
中科院分区：
文献类型：
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作者：
DALLINGER, R;BERGER, B;KAGI, JHR
采用凝胶渗透、离子交换和反相高效液相色谱法从接触金属的罗马蜗牛（Helix pomatia）中纯化出镉结合金属硫蛋白。s甲基化蛋白用胰蛋白酶和内源性蛋白酶Asp-N、gluc和Arg-C消化。虽然大多数生成的肽可以通过Edman降解进行测序，但完整的蛋白质以及n端肽被证明是被阻断的。质谱分析表明，n端氨基酸为乙酰化丝氨酸残基。蜗牛金属硫蛋白含有66个氨基酸残基，其中18个为半胱氨酸残基，排列在7个Cys-Xaa-Cys基序中，被认为与镉的脱毒有关。计算得到该蛋白的分子量为6.62 kDa。蜗牛金属硫蛋白的初级结构与软体动物和脊椎动物金属硫蛋白有明确的关系，但与其他无脊椎动物金属硫蛋白的相似性较低。该分离蛋白的n端区域在目前确定的金属硫蛋白序列中是独特的，与组蛋白H2A和H4的n端序列高度相似，这可能对调节功能很重要。
A cadmium-binding metallothionein has been purified from metal-exposed Roman snails (Helix pomatia) using gel-permeation, ion-exchange and reverse-phase high-performance liquid chromatography. The S-methylated protein was digested with trypsin and the endoproteinases Asp-N, Glu-C and Arg-C. While most of the resulting peptides could be sequenced by Edman degradation, the intact protein, as well as the N-terminal peptide, proved to be blocked. Analysis by mass spectrometry showed that the N-terminal amino acid was an acetylated serine residue.Snail metallothionein, which is suggested to be involved in the detoxification of cadmium, contains 66 amino acid residues, 18 of which are cysteine residues arranged in seven Cys-Xaa-Cys motifs. The calculated molecular mass of the protein is 6.62 kDa. The primary structure of snail metallothionein reveals a clear relationship with molluscan and vertebrate metallothioneins, but lower similarity with metallothioneins of other invertebrate species. The N-terminal region of the isolated protein proved to be unique among the metallothionein sequences determined so far, showing high degrees of similarity with the N-terminal sequences of histones H2A and H4 which may be important for regulatory functions.