论文部分内容阅读
纯化与鉴定了Ｂ淋巴细胞中一种新的分子量为２１ｋＤ的钙结合蛋白（ＣａＢＰ２１）。兔阑尾淋巴细胞匀浆经热变性，Ｐｈｅｎｙｌ－Ｓｅｐｈａｒｏｓｅ与ＤＥＡＥ－Ｓｅｐｈａｒｏｓｅ柱层析，自每１ｋｇ细胞沉积物中获得ＳＤＳ－ＰＡＧＥ均一的ＣａＢＰ２１５．３ｍｇ。ＨＣｌ水解后的酸性氨基酸（Ａｓｐ＋Ｇｌｕ）含量为２６％。如同大多数钙结合蛋白一样，Ｎ末端封闭阻止其进行Ｅｄｍａｎ降解。ＣａＢＰ２１中疏水性氨基酸（计Ｇｌｙ，不计Ｔｒｐ）约占４６％，碱性氨基酸１０％，酸性氨基酸与极性氨基酸约４４％。ＣａＢＰ２１有较高的Ｓｅｒ、Ｔｙｒ含量。肽谱分析等确证ＣａＢＰ２１为２个相同或相似亚基二聚体。以ＡｒｓｅｎａｚｏⅢ作Ｃａ２＋结合分析表明每分子ＣａＢＰ２１可结合４分子Ｃａ２＋，对Ｃａ２＋的结合常数约为１０－５ｍｏｌ／Ｌ。各种性质表明ＣａＢＰ２１是一种不同于其他已知钙结合蛋白的新钙结合蛋白。
A new calcium binding protein (CaBP21) with a molecular weight of 21 kD was purified and identified from B lymphocytes. Rabbit appendix lymphocyte homogenate was subjected to thermal denaturation, Phenyl-Sepharose and DEAE-Sepharose column chromatography to obtain 15.3 mg of uniform CaBP2 from SDS-PAGE per 1 kg of cell sediment. The content of acidic amino acid (Asp + Glu) after HCl hydrolysis was 26%. Like most calcium-binding proteins, N-terminal blocking prevents Edman degradation. About 46% of the hydrophobic amino acids in CaBP21 (Gly, excluding Trp), 10% of basic amino acids, acid amino acids and polar amino acids about 44%. CaBP21 has a higher Ser, Tyr content. Peptide analysis confirms that CaBP21 is a dimer of two identical or similar subunits. Arsenazo Ⅲ for Ca2 + binding analysis showed that each molecule of CaBP21 can bind 4 molecules of Ca2 +, the binding constant of Ca2 + is about 10-5mol / L. Various properties indicate that CaBP21 is a new calcium-binding protein that is distinct from other known calcium-binding proteins.