茚三酮与赖氨酸荧光反应的研究

茚三酮与赖氨酸的显色反应已广泛用于各种样品的测定,但高灵敏的氨基酸荧光测定法的研究还很不够。尽管茚三酮与某些氨基酸的荧光反应已有报道,但反应条件苛刻,反应时间长达60～120min,对赖氨酸的专一测定法尚未见报道^[1~3]。     

Kinetic Studies on the Product Inhibition of Enzymatic Lignocellulose Hydrolysis

In order to understand the product inhibition of enzymatic lignocellulose hydrolysis, the enzymatic hydrolysis of pretreated rice straw was carried out over an enzyme loading range of 2 to 30 FPU/g substrate, and the inhibition of enzymatic hydrolysis was analyzed kinetically based on the reducing sugars produced. It was shown that glucose, xylose, and arabinose were the main reducing sugar components contained in the hydrolysate. The mass ratio of glucose, xylose, and arabinose to the total reducing sugars was almost constant at 52.0?%, 29.7?% and 18.8?%, respectively, in the enzyme loading range. The reducing sugars exerted competitive inhibitory interferences to the enzymatic hydrolysis. Glucose, xylose, and arabinose had a dissociation constant of 1.24, 0.54 and 0.33?g/l, respectively. The inhibitory interferences by reducing sugars were superimposed on the enzymatic hydrolysis. The enzymatic hydrolysis could be improved by the removal of the produced reducing sugars from hydrolysate.     

复合钙硅固硫剂的固硫反应动力学研究

用机械混合法、沉淀法及溶胶-凝胶法制备了Ca-Si系列复合固硫剂,并用热分析法分别研究其固硫性能和固硫过程,用等效粒子模型对固硫反应的动力学过程进行表征,计算了各固硫反应的动力学参数.研究结果表明,氧化钙固硫动力学参数活化能与指前因子之间存在着耦合现象,即反应活化能E_a下降时,指前因子k₀相应下降,反之,活化能增加时,指前因子相应增加.用不同方法制备的Ca-Si复合固硫剂的固硫性能和固硫过程有明显差别,但其固硫率都高于纯CaCO₃,其中溶胶-凝胶法效果最好;Ca-Si系列复合固硫剂对固硫反应的影响表现为在反应初期(即化学反应控制阶段),其反应速率较纯CaCO₃的低;而到反应后期(即产物层扩散控制阶段),其反应速率显著增加,固硫反应温度越高,这种影响越明显,与固硫转化率的实验结果非常吻合.     

超声波辅助Urea-Free试剂结合热变性快速酶解蛋白质

建立了一个超声功率-超声时间的安全区域,在此范围内进行超声波辅助酶解时,能避免超声波随机断裂蛋白质;在此安全区域内采用响应面法获得最佳超声功率和超声时间.建立了超声波辅助Urea-Free试剂结合热变性快速酶解蛋白质的方法,将蛋白质依次进行10 min超声波浴辅助Urea-Free还原烷基化反应、90 ℃热变性15 min, 超声波辅助胰蛋白酶酶解15 s.应用此快速酶解方法鉴定3种典型标准蛋白质(牛血清白蛋白、细胞色素C和肌红蛋白),在25 min内达到与传统整夜酶解方法相同的鉴定结果,并获得更高的序列覆盖率.     

Colorimetric Determination of Polyamidoamine Dendrimers and their Derivates using a Simple and Rapid Ninhydrin Assay

Abstract

A simple, accurate and rapid colorimetric method using ninhydrin reagent was developed for the determination of polyamidoamine (PAMAM) dendrimers (G4, G5, and G6) and their derivates in aqueous medium. This method was based on the interaction of the primary amino group of PAMAM dendrimers with ninhydrin reagent to form a blue‐colored product with λ_max at 570 nm. Beer's law was obeyed in the concentration range of 25–200 µg/ml of all the three investigated PAMAM dendrimers. The effects of experimental parameters such as reagent concentration and reaction time were studied to optimize the colorimetric method. Accuracy and precision of the colorimetric method were assessed by statistical analysis. Acetylated G5 PAMAM dendrimers with various acetylated rates were simultaneously measured by the described ninhydrin assay and NMR studies and the data obtained by the two methods approximately accorded with each other. Results showed that the suggested procedures were suitable for the determination of PAMAM dendrimers and their derivates in aqueous solutions with satisfactory accuracy and precision.     

对甲基二溴偶氮胂的合成及其与稀土显色反应的研究

本文报道了对甲基二溴偶氮胂的合成,该显色剂在酸性介质中与稀土元素产生高灵敏度显色反应,大多数常见元素不干扰,所拟分析方法已成功地应用于小麦和铝合金中稀土总量的测定     

计算机图象识别辅助菌种筛选及对甾体激素微生物酶反应的研究

将分形理论和计算机图象纹理分析技术移植到微生物发酵研究中，对菌落和菌丝本形态的定量描述了探讨，并利用菌种的分维特征作为筛选高产菌株的直观指标，有效地提高了菌种筛选工作的效率与准确度，探讨了沃氏底物霉菌转化的工艺过程，并以生物全息观念与分形理论为依托，在分形尺度上对生物体形态及其发育过程进行了描述，建立起菌体生长的形态动力学模型，并与生长（浓度）动力学模型相结合，设计出可判别理论最佳投料点的酶活描述     

具有cGPX活力的含硒抗体酶的酶学及动力学性质研究

通过单克隆抗体制备技术得到三株特异结合半抗原4(GSH-S-DNP二苄酯)的单克隆抗体HB4,HB5和HB7.抗体经两步化学诱变得到具有细胞谷胱甘肽过氧化物酶(cGPX)活性的含硒抗体酶mHB4,mHB5和mHB7,活力分别为170,1867,32U/μmol.其中mHB5的活力是天然兔肝cGPX的0.32倍,m4A4的1.51倍.等离子体-质谱(ICP/MS)测得每分子含硒抗体酶分子中大约存在2个硒原子.mHB5的最适pH为8.6～8.8.在pH值范围为7.0和37℃条件下,mHB5催化GSH和H₂O₂或t-ROOH反应的二级速率常数为:_k+1(H₂O₂)9.71×10⁶L/(mol·min),_k+1(t-ROOH)5.99×10⁵L/(mol·min).mHB5使非酶催化反应速率提高了9.8×10⁶和3.7×10⁵倍.     

钒(Ⅴ)—噻唑偶氮类试剂极谱催化波的研究

Ⅴ(Ⅴ)-DMTAM-DPG三元配合物在甲酸-甲酸钠-NaBrO_3中于-0.3V(vs.SCE)能产生一灵敏的吸附动力催化波。本文对此进行了研究。用于矿样中钒的测定,效果较好。     

新型若丹宁试剂应用于催化荧光法测定痕量铁的研究

1引言目前测定铁的方法主要有分光光度法、原子吸收法等。催化荧光法测定痕量铁的报道不多,且灵敏度一般较低。若丹宁类试剂多用于分光法测定贵金属,但灵敏度较低。近些年来该类试剂逐渐应用于荧光法测定金属离子,具有很高的灵敏度和好的选择性。实验合成了新型试剂3-(2′-甲氧     

Study of the Alkyl Chain Length on Laccase Stability and Enzymatic Kinetic with Imidazolium Ionic Liquids

The activity and stability of laccase and their kinetic mechanisms in water soluble ionic liquids (ILs): 1-butyl-3-methyl imidazolium chloride [C₄mim][Cl], 1-octyl-3-methyl imidazolium chloride [C₈mim][Cl], and 1-decyl-3-methyl imidazolium chloride [C₁₀mim][Cl] were investigated. The results show that an IL concentration up to 10% is satisfactory for initial laccase activity at pH 9.0. The laccase stability was well maintained in [C₄mim][Cl] IL when compared to the control. The inactivation of laccase increases with the length of the alkyl chain in the IL: [C₁₀mim][Cl] > [C₈mim][Cl] > [C₄mim][Cl]. The kinetic studies in the presence of ABTS as substrate allowed calculating the Michaelis–Menten parameters. Among the ILs, [C₄mim][Cl] was the suitable choice attending to laccase activity and stability. Alkyl chains in the ions of ILs have a deactivating effect on laccase, which increases strongly with the length of the alkyl chain.     

一类新偶氮试剂的研究——Ⅳ.试剂2-(8′-羟基喹啉-5′-磺基-7′-偶氮)-变色酸催化荧光法测定铈(Ⅲ)

根据铈(Ⅲ)对试剂2-(8′-羟基喹啉-5′-磺基-7′-偶氮)-变色酸(HQSAC)分解反应的催化作用,提出了铈(Ⅲ)的荧光催化动力学分析新方法,本法具有灵敏度高,选择性较好等特点。铈(Ⅲ)含量在0～15.0μ8/25ml呈良好线性关系,检出限为0.9ng/ml。本法已用于合成样的分析,效果良好。对该反应机制进行了初步探讨,确定了反应动力学方程,进行了反应速率和活化能的测定。     

Fluorimetric Assay for Serum Albumin Based on Its Enzymatic Activity

ABSTRACT

Serum albumins are known to catalyze the hydrolysis of aryl esters. Both human and bovine albumins are active against Naphthol AS acetate, resulting in a fluorescence excited at 320 nm and monitored at 500 nm. HSA was more active than BSA. At pH 8.0 the reaction is activated by cetyltrimethylammonium bromide. Other esterases in serum require either calcium or a higher pH for activity. The assay is conducted with albumin diluted to about 10^?7 M or less, thus dissociating many potentially interfering ligands. Palmitic acid did not interfere. The interference by bilirubin is minimized by using highly dilute albumin. The present method gives results with serum which correlate well with the widely used Bromcresol Green method. Limit of detection for HSA is 14 picomoles.     

Direct Sensitive Spectrophotometric Determination of Glyphosate by Using Ninhydrin as a Chromogenic Reagent in Formulations and Environmental Water Samples

A simple, sensitive, and rapid spectrophotometric method for the assay of glyphosate (= N‐(phosphonomethyl)glycine) in various formulations (Roundup, Excel Mera 71) and environmental water samples is described. The method is based on the reaction of glyphosate with ninhydrin in presence of sodium molybdate in neutral aqueous medium at 100° to give a Ruhemann's purple product having the VIS absorption maximum at 570 nm (Scheme, Fig. 1). The product is stable for 10 h. Beer's law is obeyed in the concentration range of 0.1–3.5 μg ml^?1. The molar absorptivity and Sandell's sensitivity are 3.2816 ? 10⁴ l mol^?1 cm^?1 and 5.2 ng cm^?2, respectively (Table 1). The method is highly reproducible, as confirmed by the relative‐standard‐deviation (r.s.d.) values (1.70%; Table 2). Recovery studies establish that this method is accurate (Table 5) and can be successfully employed for the determination of glyphosate.     

Kinetic Studies on Interactions of Ferreous-porphyrins with Hydrogen Peroxide

In an alkali-methanol solution, both 1- and 2-naphthol can be converted into 2-hydroxy-l,4-naphtho-quinone (HNQ) with selectivity more than 95% by H2O2 over metalloporphyrin catalyst. The UV-Vis spectra indicate that a high valence oxygen-ferreous porphyrin intermediate has been produced by addition of an aqueous solution of H2O2 into the catalytic system. This intermediate formation rate is influenced by the concentrations of low valence ferrous porphyrin H2O2, and NaOH existing in the system. With the aid of the UVVis spectrum varieties, the rate equations and formation rate constants of the intermediate at different temperatures can be determined by changing the original concentration of each reactant. The formation activation energy of this intermediate was also determined by changing temperature.     

Microwave-Mediated Modification of Selected Limonoids with DMAB Reagent and Antibacterial Studies

N,N-Dimethylaniline.borane (DMAB) is a stable, multifaceted electrophilic boron agent that displays hydroboration of C = C as well as selective reduction of functional groups under reflux, microwave, and ultrasound conditions. Natural products contain a plethora of functional groups that govern the specific bioactivity. It will be interesting to correlate the change in a functional group with the concern for change in bioactivity. Current research emphasizes the influence of microwave irradiation on moderately reactive DMAB reagent towards the functional group modification of selected limonoid-phytochemicals of Meliaceae family viz. cedrelone, azadirone, nimbin, and azadiradione. DMAB conveniently reduces the ketone, epoxide group into alcohol, and does a hydroboration reaction on the C = C bond. It does not show interest to reduce the ester group irrespective of 30 min of MW irradiation. Except for these reducing properties, the reagent DMAB unveils chemo-selective nature in respect of different functional groups and utilizes in an asymmetric synthesis. The coalescence of amine.borane with microwave irradiation brings forth a commodious and prompt method for the selective reduction of functional groups. The bioactive efficacy of modified phytochemicals is further taken for the antimicrobial studies.     

Diazatruxenes from the Condensation Reaction of Indoles with Ninhydrin

The reaction of indoles with ninhydrin has been reported to provide only 1:1 condensation products (cf. A or 8 ) that show good antioxidant and anti‐inflammatory activity. In the present work, our synthetic challenge for the synthesis of innovative, highly substituted tetra‐indole indanes of type 1 via a 4:1 condensation reaction in acetic acid gave two unexpected new products, the diazatruxene derivatives 3 and 4 . The novel structures have been characterized by their analytical and spectral data including 1D‐ and 2D‐NMR. With 5‐chloroindole, only the known 1:1 reaction.     

白血病细胞酶联免疫酶催化银沉积于插指电极阵列电化学免疫分析新方法

建立了一种检测白血病细胞表面抗原的细胞酶联免疫电化学分析新方法. 该方法兼有细胞酶联免疫分析抗原、抗体结合的特异性和插指电极阵列酶催化银沉积电化学分析的灵敏性. 在聚苯乙烯微孔板中包被白血病细胞, 先后加入鼠抗人抗体及碱性磷酸酶(ALP)标记的马抗鼠抗体, ALP催化抗坏血酸磷酸酯(AAP)水解成抗坏血酸(AA), AA使银离子还原成银单质并沉积到插指电极阵列表面, 导致插指电极阵列上相邻两个梳齿导通. 通过对电导率的测定, 可实现对细胞表面抗原的高灵敏分析. 此分析方法灵敏度高(可检测出50个左右的HL-60细胞)、特异性好, 且可用于大量样品的分析, 为白血病等肿瘤疾病的早期诊断和免疫分型提供了新技术. 此外, 该方法也可用于细胞表面分子基因工程抗体活性的检测.