Increased nucleophile reactivity of amino acid beta-naphthylamides in alpha-chymotrypsin-catalyzed peptide synthesis

Alpha-chymotrypsin-catalyzed acyl transfer from Boc-L-MetONp, Ac-L-TyrOEt, Bz-L-TyrOMe, Mal-L-PheOMe to the C-protected amino acids (L-AlaNH2, L-LeuNH2, L-ArgOMe and beta-naphthylamides of L-Arg, L-Leu, L-Ala and L-Glu) has been studied. Modification of the carboxylic groups with beta-naphthylamide was shown to increase the reactivity of nucleophiles in these reactions by a factor of more than 100 in comparison with amides and esters of the same amino acids. This effect can be accounted for by the effective formation of the nucleophile-acylenzyme complex due to hydrophobic interactions of the beta-naphthylamide moiety with the corresponding subsite of alpha-chymotrypsin. The reaction kinetics follows the scheme involving hydrolysis of the nucleophile-acylenzyme intermediate. The contribution of this pathway depends on the structures of both the acyl-group donor and the added nucleophile. The competitive inhibition by amino acid beta-naphthylamides is also observed. The results obtained show that modification of the COOH-group of added nucleophiles by beta-naphthylamide strongly affects the reactivity of these compounds in the alpha-chymotrypsin-catalyzed peptide synthesis.     

一种快速鉴定转基因植物纯合体的新方法

植物转化中鉴定转基因植物的整合性是一个很重要的步骤,常规方法是对独立分离的转基因T1代植株产生的T2代进行转基因分离比率研究,以检测T1代的转基因整合状态,不仅费时费力,而且浪费了T1代资源。本介绍一种应用双重定量实时PCR技术鉴定转基因植物纯合子的新方法：以T1代植物DNA为模板,根据转基因后代的Ct表型值鉴定其转基因整合状态,Ct值接近2的为转基因纯合型,Ct值接近1的为转基因杂合型。用这种方法,可以同时对数十个T1代转基因幼苗的整合状态进行快速鉴定,准确率为100％。     

光学分子影像技术及其在药物研发领域的应用

光学分子影像技术是一种发展迅速的生物医学影像技术,能够利用生物发光技术或荧光蛋白等,对生物体内特定的生物过程进行无创的定性或定量研究。应用该技术可以对药物进行筛选,选取具有潜在治疗效果的药物进行后续研究,而终止对可能无效药物的研究,同时可以评价药物对肿瘤的代谢、增殖、血管形成、凋亡和组织乏氧等方面的影响。本文主要介绍光学分子影像技术及其在药物研发,尤其是抗肿瘤药物研发领域的应用。     

Bleomycin in the Reticuloses

Bleomycin alone was used in the treatment of 54 patients with Hodgkin''s disease in its later stages, 17 with generalized lymphosarcoma, 22 with reticulum cell sarcoma, and 7 with mycosis fungoides. The patients had had radiotherapy and full courses of conventional chemotherapy. Bleomycin was given in doses of 30 mg weekly to an average total dosage of 200 mg, though up to 800 mg could be given because of its marrow-sparing properties. Sixteen (29%) of the patients with Hodgkin''s disease remitted, most of them achieving only a partial remission, and similar results were obtained in the other three reticuloses. Bleomycin would seem to have some beneficial action in the late stages of Hodgkin''s disease, though it is less effective than some drug regimens recently introduced. Nevertheless it may be useful when there is diminished bone marrow reserve. It would be a suitable drug to use in combination therapy of these four reticuloses.     

乌头及其同属近缘种的SSR指纹图谱研究

乌头(Aconitum carmichaeli Debx.)为中国重要的药用植物,种质资源丰富,同属近缘种繁多。该研究采用SSR分子标记技术对采自17个种群的51份乌头样本和13个同属近缘种的65份样本进行扩增和聚丙烯酰胺凝胶电泳检测,分析了乌头及其同属近缘种的遗传多样性、遗传分化和系统发育关系,筛选出稳定性好、多态性高的SSR引物构建乌头及其近缘种的指纹图谱。结果表明:(1)11对乌头微卫星引物均表现出高的多态性,共检测出109个复等位基因,平均每个位点9.91。(2)乌头在物种水平上遗传多样性丰富(A=3.090 9,I=0.889 7,h=0.540 2),种群间的遗传分化显著(Gst=0.277 4);乌头属14种植物表现出了较高的遗传多样性(A=9.909 1,I=1.526 2,h=0.690 5),物种间遗传分化显著(Fst=0.437),基因流微弱(Nm=0.451 8)。(3)聚类分析表明,同一种群的乌头样本首先聚在一起各自形成小支,17个小支聚为一支;13个乌头近缘种材料中,相同物种的样本分别聚为一支;乌头属14个物种聚为5个大支,与形态分类结果一致。(4)利用基因型丰富、多态性高的6对SSR引物(Tchin03、Tchin04Tchin20、Tchin26、Tchin29、Tchin32)可有效区分14种乌头属植物,并以此建立了乌头种质资源和近缘种的DNA指纹图谱。该研究为乌头的种质资源鉴定及混伪品鉴定提供了重要的技术支撑。     

Cisplatin: nephrotoxic action in vertebrates and its prevention

1. The kidney of frog and black sculpin appeared to be much less sensitive to the toxic action of CP in comparison with rat and pigeon. 2. The impairment of renal function after CP administration resulted in increased serum urea in rat, uric acid in pigeon and magnesium in black sculpin. 3. Kidney swelling is important feature of CP nephrotoxicity in rat and pigeon but not in frog and fish. 4. Pretreatment with choline chloride, PAH, furosemide and ethacrynic acid reduced the nephrotoxic action of CP in rat but did not prevent the accumulation of platinum in renal tissue which appeared to be a function of the dose injected to investigated animals.     

Well-defined linear Au<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> (<Emphasis Type="Italic">n</Emphasis> = 2–4) chains encapsulated in SWCNTs: a DFT study

One-dimensional (1D) gold nanostructures have been extensively studied due to their potential applications in nanoelectronic devices. Using first-principles calculations, composites consisting of a well-defined linear Au _n (n?=?2–4) chain encapsulated in a (9,0) single-walled carbon nanotube (SWCNT) were studied. The translational energy barrier of a single Au atom in a (9,0) SWCNT was found to be 0.03 eV. This low barrier guaranteed the formation of Au _n @ (9,0) SWCNT (n?=?1–4) composites. Bond lengths, differential charge densities, and electronic band structures of the composites were studied. The average Au–Au bond lengths in the composites were found to be almost the same as those in the corresponding free-standing linear Au _n . The average bond length increased as the number of Au atoms increased. Charge transfer in all of these composites was slight, although a few valence electrons were transferred from the (9,0) SWCNT and the Au chains to intercalations. The conductivities of the encapsulated linear Au _n (n?=?2–4) chains were enhanced to some extent by encapsulating them in the SWCNT.     

Behavioral modification in choice process of Drosophila

Because of its clear genetic and developmental background, diversity of behavioral paradigms and neuroanatomy of the brain, Drosophila has become an important animal model for studying genetic, molecular and cellular bases of learning and memory[1]. Extensive research has explored the visual operant conditioning of Drosophila and related molecular bases[2—8]; recently, researchers began to address cognition-like functions and involved neural substrates[9—11]. In these studies, behavioral ana…