Chemistry on Peptides Induced in Plants Treated with Cadmium Ion

在经镉离子处理的裂殖酵母中发现了镉蛋白。它们的结构特征是含有γ-谷氨酰-半胱氨酸结构，并已通过微量化学反应和酶促反应确定。其中之一是钙蛋白酶的荧光DACM衍生物的HPLC分析。另一个是它们的4-乙烯基吡啶衍生物在255 nm处具有特定紫外吸收的HPLC分析。虽然后者的灵敏度并不比前者更好，但后者的方法适合于分析钙蛋白酶的分子种类，因为衍生物形成反应提供了对应于相应钙蛋白酶的单一产物，并且因为衍生物在分析过程中足够稳定。前一种方法灵敏度高，适合于痕量钙蛋白酶的检测。采用前一种方法测定钙离子浓度， ...更多信息 在Cd ^++处理的水稻根中，诱导了ns。结果表明，未处理根中主要的SH肽是谷胱甘肽（GSH），Cd ^++处理后，在GSH含量显著下降的同时，又诱导了钙调素的合成。一个有趣的特异性羧肽酶（CP酶）的结构分析中发现的应用于此目的。这是CP酶不切割γ-Glu-Cys键而切割Cys-Gly和Cys-Glu键的特异性。在高底物浓度条件下用CPase Y处理GSH。酶促反应主要得到6种产物。其中2个为cadystin（gamma EC）_2G和（gamma EC）_3G。其它产物为（γ EC）、（γ EC）_2、（γ EC）_3和（γ EC）_2的二次产物。结果表明，在高底物浓度条件下，CPase Y代谢GSH的主要途径是还原型谷胱甘肽，并建立了一种一步合成钙调素的方法。少

Cadystins had been found in a fission yeast treated with cadmium ion. Their structures are characteristic to contain gamma-glutamyl-cysteine moiety and had been determined by means of micro-chemical reactions and enzymic reactions.During the present research, two methods to analyze cadystins specifically were established. One of them is HPLC analysis of fluorescent DACM derivatives of cadystins. The other one is HPLC analysis of their 4-vinylpyridine derivatives bearing specific UV absorbance at 255 nm. Although the sensitivity of the latter is not better than the former, the latter method was suitable to analyze the molecular species of cadystins because the derivate formation reaction afforded a single product corresponding to the respective cadystins and because the derivatives are stable enough during the analysis. The former method is suitable to detect trace amount of cadystins,because it is more highly sensitive than the latter. The former method was applied to determine cadysti … More ns induced in the root of rice plant treated with Cd^<++>. The results suggested that glutathione (GSH) is the major SH peptide in non-treated root, and that cadystins were newly induced accompanied by dramatic decrease of GSH, by treatment with Cd^<++>.Next, the enzymic synthesis of cadystins was examined. An interesting specificity of carboxypeptidase (CPase) found in the structure analysis was applied for this purpose. That is the specificity that CPase does not cleave gamma-Glu-Cys bond and that it cleaves Cys-Gly and Cys-Glu linkage. GSH was treated with CPase Y under a high substrate concentration condition. The enzymic reaction afforded major 6 products. Two of them were cadystin (gamma EC)_2G and (gamma EC)_3G. The other products were (gamma EC), (gamma EC)_2, (gamma EC)_3, and dehydrate product of (gamma EC)_2. The results suggested the major metabolic pathway of GSH by CPase Y under high substrate concentration condition and a method to synthesize cadystins in a simgle step was established. Less