立体选择性脂肪酶的筛选及其在薄荷醇拆分中的应用

采用双平板透明圈方法,筛选得到1株能够选择性水解L-薄荷醇丙酸酯的微生物。通过16sDNA测序,鉴定为产碱假单胞菌Pseudomonas alcaligenes。该菌所产脂肪酶可水解4对薄荷醇丙酸酯,在35℃时绝对转化率达到50％时,表现出较高的对映体过量值（e.e.p〉99％）与非对映体过量值（d．e．p〉90％）。这一结果表明,产碱假单胞菌脂肪酶是具有工业应用前景的生物催化剂。     

Cloning and functional analysis by gene disruption of a novel gene involved in indigo production and fluoranthene metabolism in Pseudomonas alcaligenes PA-10

A novel indole dioxygenase (idoA) gene has been cloned from Pseudomonas alcaligenes PA-10, based on its ability to convert indole to indigo. The chromosomally encoded idoA gene exhibits no similarity to previously cloned naphthalene dioxygenases or to aromatic oxygenases from other species at the nucleotide level. Phylogenetic analysis indicates that the idoA gene product is most similar to an acyl-CoA dehydrogenase from Novosphingobium aromaticivorans. The enzyme encoded by the idoA gene is essential for the metabolism of fluoranthene, since a mutant in which the idoA gene has been disrupted looses the ability to degrade this compound. The idoA gene appears to be constitutively expressed in PA-10, but its expression is also subject to regulation following prior exposure to salicylate and to fluoranthene degradative intermediates.     

Chitin Coated Cellulose as an Adsorbent of Lysozyme-like Enzymes: Some Applications

Galactose oxidase was purified from the culture supernatant of Gibberella fujikuroi by ammonium sulfate precipitation, chromatographies on DEAE-cellulose and hydroxylapatite, and gel filtration on Bio-Gel P-100. The purified enzyme had a molecular weight of 90,000 and an isoelectric point of pH 3.7, and contained about one atom of copper and about one atom of iron per mol of the enzyme protein. The enzyme was markedly inactivated by a copper-chelating agent, diethyldithiocarbamate, and reducing agents. The apoenzyme preparing on treatment of the enzyme with diethyldithiocarbamate could be reactivated only by the addition of either Cu⁺ or Cu^{2 +}. These results indicate that copper is involved in galactose oxidase activity of G. fujikuroi.     

芳香烃龙胆酸降解途径蛋白质组学的研究

芳香烃是一类重要的环境污染物,微生物降解是其主要的处理方法。研究显示降解过程中产生保守型和诱导型的各一组同工酶。目前,仅有保守型的龙胆酸加双氧酶（GDOI）及其下游片段被克隆。产碱假单胞菌NCIB9867（P25X）的突变株-SNZ28 GDOI被打断,在龙胆酸诱导的情况下,该突变株仍能检测到龙胆酸加双氧酶活性。采用二维蛋白电泳分析突变株SNZ28在有和没有龙胆酸诱导条件下的蛋白质表达差异。电泳结果显示了两者存在有15个蛋白点的差异。通过MALDI-TOF和Q—TOF分析,其中的12个蛋白质点与数据库中已知多肽片段有同源性。其中,P4点与青枯菌（Ralstonia species）龙胆酸1,2加双氧酶同源。该结果在蛋白质组学上证实了GDOII的存在。     

Metabolic pathway of homophthalic acid in Pseudomonas alcaligenes

Abstract A microorganism capable of degrading homophthalic acid as a sole source was isolated from garden soil. The strain was identified as Pseudomonas alcaligenes . The organism degraded homphthalate by a pathway which involved phenylactate and p -hydroxyphenylacetate as intermediates. The intermediates have been identified by physico-chemical methods. A tentative pathway for the degradation of homophthalate is proposed based on isolation of intermediates, oxygen uptake studies and presence of enzymes involved in the degradation.