【摘要】 小麦黄化胚芽鞘经苯基琼脂糖亲和层析提取和纯化,其细胞壁CaM在有钙和缺钙时SDS电泳呈现不同的迁移率;依赖Ca²⁺与苯基疏水结合;在紫外吸收光谱上具有五个特征峰;对PDE的激活剂量反应曲线和从非活性状态向活性状态转变时所需的Ca²⁺浓度均和胞内CaM相同,说明细胞壁CaM和胞内CaM具有相同的基本理化特性。采用CaM琼脂糖亲和层析,发现在小麦细胞壁中存在CaM结合蛋白,其中以分子量为40.7 kD的 CaM结合多肽为主。细胞壁CaM结合蛋白不具有过氧化物酶、ATP酶或酸性磷酸酯酶的活性。更多还原

【Abstract】 Our previous study demonstrated that CaM（calmodulin） exists in wheat cell wall by usingPDE assay and ELISA. However, the Ca²⁺concentration in plant cell wall is much higherthan that required for the regulation of CaMactivity （～1μmol/L）, and also no evidencechows that there is a mechanism regulating Ca²⁺level in plant cell wall. The purpose of the pre-sent study is to characterize the biochemicalproperties of plant cell wall CaM,and to searchfor CaM-binding proteins in plant cell wallwhich might participate in some cell wall phy-siological processes. The results of this study areas follows: 1. Cell wall CaM was purified from wheatetiolated coleoptiles by DEAE-cellulose andphenyl-Sepharose affinity chromatography. 2. Wheat cell wall CaM binds hydropho-bically to the phenyl group in a Ca²⁺-dependentmanner. It shows different mobility on SDS-polyacrylamide gels in the presence or absenceof Ca²⁺, and 5 specific peaks on UV absorbancespectrum. The dose-response curve for the acti-vation of PDE and the Ca²⁺ concentration re-quired for converting the inactive state to theactive one are the same both in cell wall CaMand in intracellular CaM. The results provideunequviocal proof that the wheat cell wall CaMshares the same biochemical properties as thatof the intracellular CaM. 3. It was found by CaM-Sepharose chro-matography that there exist several CaM-binding proteins in wheat cell wall, of which theone having a molecular weight of 40700 is pos-sibly the main CaM-binding polypeptide. Noactivity of enzymes such as peroxidase, ATPaseor acid phosphatase was detected in this prepara-tion.更多还原