ABSTRACT
As a novel fungal type Ⅲ polyketide synthase, CsyB from Aspergillus oryzae can sequentially accept one molecular short chain fatty acyl CoA as start unit, one molecular malonyl-CoA and one molecular acetoacetyl-CoA as extend unit to produce the short chain csypyrone B1-3. On the basis of crystal structure of CsyB, a fatty acyl CoA binding tunnel of a length of about 16 Å is located in its active center that is proposed to accept diversified start units. In order to examine the substrate diversity of CsyB, CsyB gene was introduced and expressed in Escherichia coli that contained a number of precursors of long chain fatty acyl CoA in vivo. The results of HPLC revealed that a series of long chain csypyrone derivatives were detected in the recombinant strain in comparison with the control strain. These new csypyrone compounds were preliminarily analyzed by UV-visible spectroscopy and LC-HRMS. Three hydroxylated csypyrones were intensively determined by 1D and 2D NMR experiments, especially the position of the hydroxyl group in these compounds. These results demonstrate that CsyB exhibits a broad substrate specificity, which not only can accept the long chain saturated or unsaturated fatty acyl CoA as substrate, but also accept hydroxylated long chain fatty acyl CoA.
ABSTRACT
Objective To observe the expression of HER-2 and TOPO-Ⅱα in ovarian epithelial cancer,analyze the correlation between their expression and provide theoretical basis for clinical diagnosis,prognosis and treatment. Methods Expression levels of HER-2 and TOPO- Ⅱα in 10 normal ovarian tissues,20 benign tumors and 58 cases of ovarian epithelial cancers were detected by immunohistochemical method, and their correlations with pathological features were analyzed. Results The positive expression rate of HER-2 in normal ovarian and benign tumor tissues were significantly lower than ovarian epithelial cancers respectively ( 10. 0% , 15.0% VS 46. 6% ;P ＜ 0. 05 ). The positive expression rate of TOPO- Ⅱα in ovarian epithelial cancers was significantly higher than normal and benign epithelial ovarian tumor tissue (53.4% vs 10. 0%, and 15.0%,Ps ＜ 0. 05 ), but we did not find significant difference in the comparison between normal and benign epithelial ovarian tumor tissue ( Ps ＞ 0. 05 ). The expression of HER-2 and TOPO- Ⅱα were significantly correlated with clinical stages, histological differentiation of tumor cells (Ps ＜ 0. 05 ) ,but there were no correlations between the age or histological type. In ovarian cancer tissues, a positive correlation between the expression of HER-2 and TOPO- Ⅱα was observed ( r = 0. 324, P ＜ 0. 05 ) . Conclusion The overexpression of HER-2 and TOPO- Ⅱαplay an important role in ovarian carcinogenesis and development. The expression of HER-2 is positively correlated with TOPO- Ⅱα in ovarian epithelial cancers. Coexpression of the two moleculars may be involved in the development and progression of ovarian epithelial cancer, which should be further studied.