植物胞外钙调素与拮抗剂W7-Agarose结合作用的荧光光谱法研究

W 7-agarose是常用的细胞外CaM功能的拮抗剂,本实验采用荧光光谱法研究了水溶液中钙调素拮抗剂W 7-agarose与植物胞外钙调素的相互结合反应。W 7-agarose是一种将W 7-共价连接到颗粒型agarose(琼脂糖)的粒子。W 7-agarose颗粒较大且容易沉淀,静置5m in后,溶液中的荧光强度完全由游离的CaM产生。在溶液中加入W 7-agarose后,溶液中一部分CaM与其结合后沉降至荧光比色皿底部,导致溶液中CaM的荧光强度下降。由此可以确定溶液中游离CaM的浓度。根据公式lg{[Q]t(F0-F)/F0}=nlg{[Q]tF/F0} lgnK[B]t,从而计算出配位体系的结合常数和配比。研究表明:二者以摩尔比1∶1结合,其平衡常数为4.9×105。由此进一步计算了W 7-agarose对胞外钙调素的拮抗率,在拮抗剂W 7-agarose浓度达到15~20μmol/L时,拮抗率可达到90%以上,与文献报道的生物学体内实验结果一致,从分子水平上解释了W 7-agarose与CaM的结合作用。     

Design,Synthesis, and Cytotoxic Activity of Novel Natural Arylsulfonamide-Inspired Molecules

Primary arylsulfonamide functional groups feature prominently in diverse pharmaceuticals. However, natural arylsulfonamides are relatively infrequent. In this work, two novel arylsulfonamide natural products were first synthesized, and then a series of novel molecules derived from natural arylsulfonamides were designed and synthesized, and their in vitro cytotoxic activities against A875, HepG2, and MARC145 cell lines were systematically evaluated. The results indicate that some of these arylsulfonamide derivatives exhibit significantly good cytotoxic activity against the tested cell lines compared with the control 5-fluorouracil (5-FU), such as compounds 10l, 10p, 10q, and 10r. In particular, the potential molecule 10q, containing a carbazole moiety, exhibited the highest inhibitory activity against all tested cell lines, with IC₅₀ values of 4.19 ± 0.78, 3.55 ± 0.63, and 2.95 ± 0.78 μg/mL, respectively. This will offer the potential to discover novel drug-like compounds from the sparsely populated area of natural products that can lead to effective anticancer agents.     

The effect of Lycium barbarum polysaccharide on alcohol-induced oxidative stress in rats

The aim of this study was to investigate the effects of Lycium barbarum polysaccharide (LBP) on alcohol-induced liver damage in rats. A total of 36 rats were divided into control, ethanol and ethanol + LBP groups. Rats in the ethanol group were fed 7 g ethanol/kg body weight by gastric infusion, three times a day, for 30 consecutive days, while rats in the control group received the same volume of physiological saline instead of ethanol, and rats in ethanol + LBP group were fed both ethanol (7 g/kg body weight) and LBP (300 mg/kg body weight/day). Alcoholic liver injury was examined by serum ALT and AST activities, alcoholic fatty liver was assessed by lipid levels, and oxidative stress was evaluated by SOD, CAT, GSH-Px, GSH and MDA assays. In the ethanol group, a significant elevation of enzymes and lipid in serum, increased MDA level and depletion of SOD, CAT, GSH-Px and GSH in liver were observed. LBP administration significantly ameliorated liver injury, prevented the progression of alcohol-induced fatty liver, and improved the antioxidant functions when compared with the ethanol group. Histopathological examination of rat liver revealed that LBP administration protected liver cells from the damage induced by ethanol. The results suggest that LBP is a promising agent to protect the liver from hepatotoxicity and fatty liver induced by ethanol intake.     

Synthesis and Antifungal Activity of Substituted 2‐Aryl Benzimidazoles Derivatives

Benzimidazole fungicides were among the early systemic fungicides developed and used for controlling a wide variety of plant diseases. During the course of our screening process for active compounds, two 2‐aryl benzimidazoles derivatives bearing sulfoxide group ( 6b and 6c ) have been demonstrated to exhibit good inhibition activity against high‐resistant isolate of Botrytis cinerea compared with carbendazim, and the inhibition rates are up to 46.67% and 51.11% at the concentration of 10 μg/mL, which might be considered as the active framework for the discovery of novel fungicide to high‐resistant isolate of B. cinerea.     

Borate complexes of benzohydroxamic acid and some of its derivatives

Ultraviolet spectrophotometric measurements in dilute aqueous solution give pK(a) values of 8.78, 8.27, 8.96 and 8.68, respectively, for benzohydroxamic, N-phenylbenzohydroxamic, p-methoxybenzohydroxamic and N-methyl-p-methoxybenzohydroxamic acids. The acids carrying no substituent on nitrogen form 1:1 complexes with boric acid according to the general equation RCONHOH + H(3)BO(3) --> (1:1 complex)(-) + H(+). Equilibrium constants (log K) were found to be -5.70 for benzohydroxamic acid and -5.8 for p-methoxybenzohydroxamic acid. The complexes behave as very weak monoprotic acids and decompose at high pH to yield borate ions and the corresponding hydroxamate ions. The N-substituted hydroxamic acids showed no reaction with boric acid under the same conditions.     

The discretized flow on domains of attraction: a structural stability result

It is well known that, for stepsize sufficiently small, compactattractors of ordinary differential equations persist underdiscretization. The present paper describes the structure ofthe discrete-time dynamical system obtained via discretizationon A(M_h)\M_h where M_h is the approximate attractor and A(M_h)is its domain of attraction. The existence of a smooth embeddinginto a continuous-time parallelizable flow is proved. The constructioncan be used to define sections for discretizations and can beinterpreted as a justification of the method of modified equations.     

A Sparse Structured Shrinkage Estimator for Nonparametric Varying-Coefficient Model with an Application in Genomics

Many problems in genomics are related to variable selection where high-dimensional genomic data are treated as covariates. Such genomic covariates often have certain structures and can be represented as vertices of an undirected graph. Biological processes also vary as functions depending upon some biological state, such as time. High-dimensional variable selection where covariates are graph-structured and underlying model is nonparametric presents an important but largely unaddressed statistical challenge. Motivated by the problem of regression-based motif discovery, we consider the problem of variable selection for high-dimensional nonparametric varying-coefficient models and introduce a sparse structured shrinkage (SSS) estimator based on basis function expansions and a novel smoothed penalty function. We present an efficient algorithm for computing the SSS estimator. Results on model selection consistency and estimation bounds are derived. Moreover, finite-sample performances are studied via simulations, and the effects of high-dimensionality and structural information of the covariates are especially highlighted. We apply our method to motif finding problem using a yeast cell-cycle gene expression dataset and word counts in genes' promoter sequences. Our results demonstrate that the proposed method can result in better variable selection and prediction for high-dimensional regression when the underlying model is nonparametric and covariates are structured. Supplemental materials for the article are available online.     

植物钙调素与Ce3+离子结合反应的荧光光谱法研究

水合Ce^3＋离子发射强荧光,而用Ce^3＋滴定植物钙调素（CaM）时,Ce^3＋离子荧光被完全淬灭,据此建立了测定Ce^3＋离子与植物钙调素结合位点数及逐级结合常数的方法。实验表明,Ce^3＋离子与植物钙调素的荧光激发光谱及发射光谱形状与光谱强度都有显著差别,前者的荧光强度远大于后者,故CaM存在时可以测定游离Ce^3＋的浓度。Ce^3＋离子荧光淬灭法测定结果说明,在0.5 mol·L^-1KCl溶液中,CaM有4个Ce^3＋离子结合位点。进一步通过Ce^3＋滴定植物钙调素的实验,并结合Excel规划求解法,计算出Ce^3＋与CaM的结合常数,K1=4.17×10^7,K2=1.26×10^7,K3=1.89×10^6,K4=2.04×10^6。     

脂肪酶催化Michael加成反应合成苄丙酮香豆素抗凝血剂及其衍生物

以含水有机溶剂作为反应介质,以爪哇毛霉的天野脂肪酶M作为生物催化剂,利用4-羟基香豆素和α,β-不饱和酮的Michael加成反应,经一步催化合成了抗凝血剂苄丙酮香豆素及其衍生物;考察了反应条件对产物收率的影响.结果表明,该合成路线反应条件温和,产物收率高,有一定的实际应用意义.