黑曲霉胞外葡萄糖淀粉酶的纯化及特性

黑曲霉（Ａｓｐｅｒｇｉｌｌｕｓｎｉｇｅｒ７２８）的粗酶液，经硫酸铵沉淀，ＳｅｐｈａｄｅｘＧ－２５柱凝胶过滤脱盐，ＤＥＡＥ－Ｔｏｙｏｐｅａｒｌ离子交换柱层析和ＳｅｐｈａｃｒｙＳ－１００凝胶层析纯化，经ＰＡＧＥ鉴定为一条带ＳＤＳ凝胶电泳测定分子量为７００００．金属离子Ｆｅ３＋对该酶有一定的抑制作用，该酶的等电点为３．７，最适ｐＨ为４，最适温度为６０℃．Ｅ２８０１％为１５．７２，Ｋｍ值为０．１１２×１０－３ｍ．     

重组人甲状旁腺激素(1-34)在大肠杆菌中的表达与纯化

将化学合成的rhPTH(1-34)基因用PCR扩增后,克隆至表达载体pET-35b( ),使rhPTH(1—34)融合于纤维素结合结构域(CBDdos)的羧基端,并得到高效表达．融合蛋白经纤维素树脂亲和层析纯化后,经Factor Xa裂解释放出rhPTH(1-34),再通过纤维素树脂亲和层析、C4反向高效液相色谱纯化得到rhPTH(1-34)纯品．每升培养液可获取3mg高纯度的rhPTH(1-34)．经质谱测定,所得样品的分子量为4117．0Da,与rhPTH(1—34)理论分子量一致．     

Isolation,purification and characterization of a new organphosphorus hydrolase OPHC2

A bacterium with the capability of degrading organphosphorus, identified as Pseudomonas pseudoaicaligenes, is isolated from OP-treated soil. The organphosphorus hydrolase OPHC2 from this bacterium has been purified and characterized. OPHC2 has optimum activity for the reaction at 65℃ and pH 9.0 with methyl parathion as a substrate, it also shows good thermal and pH stability. Most metal ions and chemicals have no effect on the activity of OPHC2. The analyses of nucleotide sequence encoding OPHC2 and amino acid sequence of OPHC2 show that there are lower homologies with those of organphosphorus hydrolase reported in GenBank.     

Structure and morphogenesis of bacteriophage T4

Bacteriophage T4 is one of the most complex viruses. More than 40 different proteins form the mature virion, which consists of a protein shell encapsidating a 172-kbp double-stranded genomic DNA, a tail, and fibers, attached to the distal end of the tail. The fibers and the tail carry the host cell recognition sensors and are required for attachment of the phage to the cell surface. The tail also serves as a channel for delivery of the phage DNA from the head into the host cell cytoplasm. The tail is attached to the unique portal vertex of the head through which the phage DNA is packaged during head assembly. Similar to other phages, and also herpes viruses, the unique vertex is occupied by a dodecameric portal protein, which is involved in DNA packaging.Received 18 February 2003; received after revision 16 April 2003; accepted 9 May 2003     

干燥激光净化能量密度阈值研究

论述了干燥激光净化的物理机制，应用力学平衡条件求出干燥激光净化时粒子逸出表面的脱附力以及单脉冲情况下干燥激光净化的辐照能量密度阈值，讨论了能量密度阈值随温度的变化规律．结果表明：干燥激光净化的能量密度阈值随温度升高而减小．     

芦荟超氧化物歧化酶的纯化与部分性质

芦荟粗提取液经丙酮沉淀、热处理、DEAE-琼脂糖柱层析和Sephacryl S-200凝胶过滤纯化后得到3种电泳纯的SOD组分,即SOD-Ⅰ、SOD-Ⅱ、SOD-Ⅲ.分子量分别为46000D,35000D,40000D;亚基分子量分别为23000D,17000D,20 000D,说明芦荟SOD三种组分均为二具体,其等电点分别为8.90,7.60,7.35。抑制剂敏感性实验和元素分析结果表明3种芦荟SOD组分均为Fe-SOD.     

超滤分离纯化麦胚蛋白酶解物的研究

采用超滤法从麦胚蛋白酶解物中初步分离纯化抗氧化活性肽,考察了操作压力、操作温度及料液浓度等工艺参数对超滤过程中膜通量的影响,并对超滤前后麦胚蛋白酶解物的相对分子质量分布、氨基酸组成及抗氧化活性进行了比较.结果表明:采用截留相对分子质量3000的聚砜膜对麦胚蛋白酶解物进行超滤分离的最适工艺条件为操作压力0.30 MPa、操作温度20 ℃、麦胚蛋白酶解物浓度35 g/L;超滤有效地除去了料液中相对分子质量较大的组分,麦胚蛋白酶解物中相对分子质量1 000～500及500～130的组分分别为23.81%、48.63%,其抗氧化活性得到提高,清除O2-·的IC50由超滤前的1.64 mg·mL-1降至超滤后的1.29 mg·mL-1.图5,表3,参13.     

芦荟超氧化物歧化酶(SOD)的分离纯化研究

采用硫酸铵分级沉淀、Sephadex G-100凝胶层析和DEAE-52柱层析,分离纯化了芦荟(A.vera L.)超氧化物歧化酶,纯化倍数为56倍,回收率为54%,比活力为643(U/mgpro),酶的最适pH值为8.2,最适温度在40~55℃,KCN和H2O2能抑制酶活性。实验表明:芦荟中的SOD属Cu、Zn-SOD。     

濒危植物桫椤过氧化物酶的分离纯化与性质

将齿叶黑桫椤叶片提取液经硫酸铵盐析、透析、DEAE-琼脂糖凝胶柱层析和Sephacryl S-200凝胶柱层析分离得到纯化的POD,其纯化倍数为26.29,回收率为27.04%;通过SDS-PAGE法测得POD的分子量为43000D;通过IEF-PAGE法测得POD的等电点为4.55;齿叶黑桫椤POD最适pH在4左右;最适温度在45℃左右;Km值在最适温度45℃、最适pH4的条件下为0.07 mol/L。     

高等水生植物的分布对富营养化水体的影响

选取4个不同样地,研究了水生植物的分布与富营养化水体中总氮（TN）、总磷（TP）、叶绿素a（Chla）及几种重金属含量的关系.结果表明,水体中总氮含量、总磷含量、叶绿素a含量、重金属总含量大小顺序依次为：高等水生植物生物量大的样地〈高等水生植物生物量小的样地〈没有高等水生植物的样地,说明高等水生植物可显著提高水体透明度,净化富营养化水体.