【摘要】 采用交换吸附脱色及柱层析新技术,成功地从烟叶中分离和纯化了一种烟草过氧化物酶同工酶(TOPI),并对其进行了一系列光谱特性研究。基质辅助激光解吸电离飞行时间质谱(WALDI-TOF-MS)测得TOPI分子量为21888.5,等电点pI为3.5;氨基酸组成分析表明TOPI为一含血红素的酸性蛋白酶。光谱学分析揭示,在402nm处有一典型的Soret带,在498和636nm处有特征吸收峰(α,β带),酸度和变性剂对TOPI在紫外可见区的特征吸收峰均产生一定的影响,TOPI的荧光光谱测定结果说明TOPⅠ分子中含有Trp残基和Tyr残基以及其自身的独特的光谱学特性。更多还原

【Abstract】 Tobacco peroxidase (TOP I ) has been purified by ammonium sulfate fractionation and column chromatography, involving ion exchange on DE-52 cellulose, gelfiltration on Sephadex G-75 and ion exchange on DEAE-sephadex A-50. The specific activity of peroxidase purified was 4 826 U/mg . It has been demonstrated by SDS-PAGE as a single band. Its molecular weight (matrix assisted laser desorption/ionization time of flight mass spectra) and isoelectric point (pI) have been determined to be 21 888.5 and 3.5 respectively. The native enzyme is one of a haemachrome-containing acidic protein and has its soret maximum at 402 nm and aand β bands at 636 nm and 498 nm, respectively. Its characteristic absorption spectra and fluorescence spectra changed in different pH and denat-urant. It has its own characteristic absorption spectra and fluorescence spectra.更多还原