蛋白质中三联氨基酸数与二级结构数的模型研究

蛋白质的一级结构或序列与二级结构的关系在蛋白质结构研究中是很重要的,通过建立模型的方法来研究这种关系.在文献中已有的模型(蛋白质一级结构中的二联氨基酸与蛋白质二级结构的模型)的基础上,建立了蛋白质一级结构中的三联氨基酸个数与蛋白质二级结构个数模型.该模型能够较准确地反映蛋白质的一级结构或序列与蛋白质的二级结构的关系,比较适合应用于氨基酸序列长度变化较大的建模数据,同二联氨基酸与二级结构模型比较,由于三联氨基酸含有更多氨基酸之间的耦合信息,该模型的拟合精度更高.由于蛋白质一级结构中的三联氨基酸的种类数很大(为4200),用以建模的变量数就很大,同时从DSSP数据库得到的样本量也很大(为11600),用以建模的数据量很大.研究结果表明,PLS变量筛选法是一种建立大数据模型有效的方法,可有效地处理变量数为4200,样本数为11600这样大数据量的建模问题.

氨基酸三联体方法评价11例心脏移植供受体匹配情况的结果分析

目的 介绍氨基酸三联体方法在评价心脏移植供受体 HL A- I类抗原配合程度中的应用 ,分析其与交叉反应组评价方法之间的结果差异 .方法 分别用上述两种方法对 11例心脏移植供受体的 HL A抗原配合情况进行评价 ,并对两种评价结果进行分析 .结果 1应用 HL A抗原交叉反应组方法分析 11例心脏移植供受体 ,其 HL A抗原配合的优劣顺序为 :例 1=例 3=例 5 =例 6 >例 7=例 9=例 11>例 2 =例 8>例 4 >例 10 ,例 1、例 3、例 5、例 6供受体配合最好 ;2应用氨基酸三联体方法分析上述 11例心脏移植供受体 ,其 HL A抗原配合的优劣顺序为 :例 3>例 5 >例 2 >例 8>例 11>例 7>例 4 >例 6 >例 9>例 10 >例 1,例 3供受体配合最好 ,例 1最差 .结论 氨基酸三联体方法从分子水平提供了多个分析参数供参考 ,能更精确地比较供受体 HL A- I抗原间的差异 ,可能更有利于供受体的筛选和评价 .

纯手性的三联吡啶氨基酸—汞(II)配合物的合成与表征

手性超分子组装是复合手性多功能材料的有效途径,是超分子化学研究的前沿领域.以纯手性三联吡啶氨基酸配体S-2(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)benzylamino)propanoic acid(Htpy)和碘化汞在水热条件下反应,合成一个新的纯手性配合物[Hg2(Htpy)2(I)4]·2H2O(1),并通过单晶X-射线衍射测试、红外光谱和元素分析对该化合物进行结构表征.在该化合物中,两个晶体学上独立的手性的单核配合物结构单元共结晶于同一晶体中.这两个手性的单核配合物结构单元各自通过配体Htpy的氨基酸基团间的氢键作用组装形成手性相反的一维螺旋链结构.

DISTRIBUTIONS OF TRIPLET CODONS IN MESSENGER RNA SECONDARY STRUCTURES

Analysis of the secondary structures of mRNAs which encode mature peptides shows that the location of each codon in mRNA secondary structure has a trend, which appears to be in agreement with the conformational property of the corresponding amino acid to some extent. Most of the codons that encode hydrophobic amino acids are located in stable stem regions of mRNA secondary structures, and vice versa, most of the codons that encode hydrophilic amino acids are located in flexible loop regions. This result supports the recent conclusion that there may be the information transfer between the three dimensional structures of mRNA and the encoded protein.

Effect of fragile histidine triad gene transduction on proliferation and apoptosis of human hepatocellular carcinoma cells

AIM:To evaluate the inhibitory effects of human fragile histidine triad(FHIT) gene on cell proliferation and apoptosis in human hepatocellular carcinoma line Hep3B in vitro. METHODS:A recombinant pcDNA3.1(+) /FHIT including the functional region of FHIT gene was constructed and transferred into human hepatocellular carcinoma cells in vitro. mRNA and protein expression of the FHIT gene in the transfected cells was detected by RT-PCR and Western blot,respectively. The effect of FHIT on proliferation was detected by MTT assay. Changes in cell cycle and apoptosis were assayed by flow cytometry. Five mice received subcutaneous transplantation of Hep3B-FHIT;5 mice received subcutaneous transplantation of normal Hep3B and Hep3B-C as controls. The body weight of nude mice and tumor growth were measured. RESULTS:RT-PCR and Western blot analysis showed that the expression level of FHIT-mRNA and FHIT protein was higher in Hep3B cells after infection withpcDNA3.1(+) /FHIT. The growth of Hep3B cells treated with pcDNA3.1(+) /FHIT was significantly inhibited. The pcDNA3.1(+) /FHIT-transfected Hep3B cells showed a significantly higher cell rate at G0-G1 phase and increased apoptosis in comparison with controls(P < 0.05) . The growth of transplanted tumor was inhibited markedly by FHIT. Tumors arising from the Hep3B-FHIT cells occurred much later than those arising from the Hep3B and Hep3B-C cells. The growth of Hep3B-FHIT cells was slow and the tumor volume was low. CONCLUSION:Transduction of FHIT gene inhibits the growth of human hepatocellular carcinoma cells and induces cell apoptosis in vivo and in vitro.