Acta Scientiarum Naturalium Universitatis Pekinensis

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Studies on Calcium Binding Proteins in Brassica Campestris Pollen

DONG Aiwu, ZHAO Tao, LI Xiaodong, ZHANG Tingfang   

  1. College of Life Sciences, Peking University, Beijing, 100871
  • Received:1998-04-27 Online:1999-07-20 Published:1999-07-20



  1. 北京大学生命科学学院,北京,100871

Abstract: Both Calmodulin(CaM) and a Neo-Calcium Binding Protein(NCBP) were purified from Brassica campestris pollen by phenyl-Sepharose CL-4B hydrophobic chromatography and DEAE-F.F. ion exchange chromatography. Two proteins were shown to be homogeneous by SDS-PAGE, PAGE and IEF. Molecular weights and pI points of pollen CaM and NCBP are 18.8 and 16.3 kD, 3.6 and 4.2 respectively. Pollen CaM can activate bovine heart cyclic nucleotide phosphodiesterase, pollen NCBP is not notable. Pollen CaM shows Calcium ion effect in both SDS-PAGE and PAGE, while NCBP only does in PAGE. The amino acid composition of pollen CaM and NCBP is different, both contain more acidic amino acids and a Cys, but lack Trp. Both of their N-terminus are blocked and C-terminus of pollen CaM is -Met-Ala-Lys-COOH. Their peptide maps in HPLC and CD spectrums are different. The Cys of pollen CaM was modified by DTNB and the PDE activity by CaM activation is marked descent. From above we can conclude that pollen NCBP is a new Calcium Binding Protein different from pollen CaM.

Key words: calmodulin, neo-calcium binding protein, brassica campestris pollen, pollen

摘要: 以油菜花粉(Brassica campestris)为材料纯化了钙调素(CaM),并得到一种新钙结合蛋白(NCBP)。经SDS-PAGE、PAGE和等电聚焦电泳(IEF)鉴定,这两种蛋白质均表现均一。CaM分子量为18.8kD, NCBP为16.3kD,等电点分别为3.6和4.2。研究证明花粉CaM具有与其他来源CaM所特有的性质,对环核苷酸磷酸二酯酶(简称PDE)有明显的激活作用,而花粉NCBP不明显。花粉CaM在PAGE和SDS-PAGE中电泳行为有Ca2+效应,而NCBP仅表现在PAGE中。经氨基酸组成分析表明两种蛋白质氨基酸组成不同,但均含有较多的酸性氨基酸,不含Trp, 含1个Cys。CaM和NCBP N-端均为封闭,CaM C-端为-Met-Ala-Lys-COOH。两种蛋白质具有不同的肽谱和CD谱。用DTNB修饰花粉CaM Cys残基,则激活PDE的能力明显下降。

关键词: 钙调素, 新钙结合蛋白, 油菜花粉, 花粉

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