Identification of protein superfamily from structurebased sequence motif

The structure-based sequence motif of the distant proteins in evolution, protein tyrosine phosphatases (PTP) Ⅰ and Ⅱ superfamilies, as an example, has been defined by the structural comparison, structure-based sequence alignment and analyses on substitution patterns of residues in common sequence conserved regions. And the phosphatases Ⅰ and Ⅱ can be correctly identified together by the structure-based PTP sequence motif from SWISS-PROT and TrEBML databases. The results show that the correct rates of identification are over 98%. This is the first time to identify PTP Ⅰ and Ⅱ together by this motif.     

胰岛素样生长因子结合蛋白7的研究进展

胰岛素样生长因子结合蛋白（IGFBP7）是胰岛素样生长因子结合蛋白超家族（IGFBPs)中一名新成员。与其他结合蛋白一样，它能与胰岛素样生长因子（IGFs)相结合，携带、转运IGF，延长IGF的半衰期，调控IGF的生物活性；更为重要的是，IGFBP7具有许多不依赖于IGF的生物作用，可参与多种类型的组织细胞的生长、发育、分化衰老与癌变等病理生理学过程。     

Effects of truncated mutants of the ε subunit of chloroplast ATP synthase on the fast phase of millisecond delayed light emission of chloroplast and its ATP synthesis ability

The ε subunit of the chloroplast ATP synthase and the truncated ε mutants which lack some amino acid residues from the N-terminus or C-terminus were overexpressed in E. coil When the ε subunit or the truncated ε proteins was added to the spinach chloroplast suspension, both the intensity of the fast phase of millisecond delayed light emission (ms-DLE) and the cyclic and noncyclic photophosphorylation activity of chloroplast were enhanced. With an increase in the number of residues deleted from the N-terminus, the enhancement effect of the N-terminal truncated proteins decreased gradually. For the C-terminal truncated proteins, the enhancement effect increased gradually with an increase in the number of residues deleted from the C-terminus. Besides, the ATP synthesis activity of ε-deficient membrane reconstituted with the ε subunit or the truncated ε proteins was compared. The ATP synthesis activity of reconstituted membrane with the N-terminal truncated proteins decreased gradually as the number of residues deleted from the N-terminus increased. For the C-terminal truncated proteins, the ATP synthesis activity of reconstituted membrane increased gradually with an increase in the number of residues deleted from the C-terminus, but was still lower than that of the wild type ε protein. These results suggested that: (a) the N-terminal domain of the ε subunit of the chloroplast ATP synthase could affect the ATP synthesis activity of ATP synthase by regulating the efficiency of blocking proton leakage of ε subunit; and (b) the C-terminal domain of the ε subunit of the chloroplast ATP synthase had a subtle function in modulating the ATP synthesis ability of ATP synthase.     

Enzymes and receptors in the leukotriene cascade

Leukotrienes are a family of paracrine hormones derived from the oxidative metabolism of arachidonic acid. These lipid mediators are recognized as important signal molecules in a variety of inflammatory and allergic conditions affecting the skin, joints, gastrointestinal and respiratory systems, in particular asthma. Such conditions are typified by local pain, tissue edema, hyperemia and functional losses. In the tissues, immunocompetent cells accumulate at the site of injury which contribute to tissue damage and perpetuation of the disease process. Leukotrienes can elicit most, if not all, of these signs and symptoms. Thus, leukotriene B₄ is one of the most powerful chemotactic agents known to date and participates in the recruitment of leukocytes. The cysteinyl leukotrienes, on the other hand, contract smooth muscles, particularly in the peripheral airways and microcirculation. Recently, drugs which block the formation and action of leukotrienes have been introduced as novel antiasthmatic medications. This chapter reviews the biochemistry, molecular biology and cell biology of the key enzymes and cognate receptors in the leukotriene cascade.     

Arginase expression in peritoneal macrophages and increase in circulating polyamine levels in mice infected with Schistosoma mansoni

We investigated the nitric oxide (NO) synthase and arginase pathways in resident peritoneal macrophages of mice infected with the tropical parasite Schistosoma mansoni. The two enzymes may have opposite effects, insofar as NO may be involved in the killing of the parasite whereas arginase may stimulate parasite growth via polyamine synthesis. We determined the effects of the infection on the expression and activity of the two enzymes in macrophages, before and after cytokine activation. Cells from infected mice expressed the hepatic type I arginase, whereas in control cells, the enzyme was expressed only after cytokine activation, as were NO synthase II and type II arginase in both groups of cells. Moreover, we found that in infected mice, arginase expression in macrophages was associated with a ten fold increase in the concentration of circulating ornithine-derived polyamines. This may be of pathological importance, since parasitic helminths are though to be dependent on their hosts for the uptake and interconversion of polyamines. Received 13 March 2001; received after revision 4 May 2001; accepted 7 June 2001     

NKC-9酸性树脂非均相催化合成查耳酮

NKC-9酸性树脂催化芳醛与苯乙酮的Claisen-Schmidt缩合合成了五种查耳酮，收率81％～92％．考察了催化剂的用量和溶剂对收率的影响．该方法产率高、操作简便．产物结构经IR、NMR数据确认．     

无溶剂条件下2-（3-氧代-1，3-二芳基丙基）丙二腈的合成

无溶剂条件下由查尔酮、丙二腈研磨一步法方便地合成2-（3-氧代-1，3-二芳基丙基）丙二腈．该反应环境友好，操作简单，并且通过IR，^1HNMR及元素分析确定了产物的结构．     

3′,5′-烃基查尔酮的合成进展

异戊烯基和香叶基结构单元普遍存在于黄酮类、查尔酮类等天然产物。异戊烯基和香叶基结构的查尔酮具有抗癌、抗氧化活性等生理活性而备受青睐。国内外报道了许多异戊烯基和香叶基结构的查尔酮合成方法。本文从苯乙酮或查尔酮为原料基础的两个研究方向进行总结,综述了近年来关于3′,5′位为异戊烯基或香叶基的查尔酮的合成方法,为更多3′,5′位为异戊烯基或香叶基的查尔酮的合成新方法被研发提供参考。