DBC-偶氮羧共振光散射法测定蛋白质

基于蛋白质对DBC-偶氮羧光散射增强的效应,拟定了一种测定蛋白质的新方法.在pH 4.1的Britton -Robinson(B-R)缓冲溶液中,蛋白质与DBC-偶氮羧结合,产生强烈的共振光散射.在362 nm处,共振光散射强度较大,且光散射强度与加入的蛋白质浓度在一定范围内呈线性关系,其中牛血清白蛋白(BSA)在0.05～7 mg·L-1、人血清白蛋白(HSA)在0.05～8 mg·L-1、溶菌酶(Lyso) 在0.05～7 mg·L-1.该法用于人血清总蛋白含量的测定,结果令人满意.     

用TBF测定人血清白蛋白的分光光度法

用分光光度法研究了四溴萤光黄二钠盐 (TBF)与人血清白蛋白 (HAS)在吐温 -60存在时的结合反应 ;在最佳反应条件下 ,以试剂空白为参比 ,TBF -HAS复合物的最大吸收波长在 5 45nm ,HSA的浓度在 0 .5～ 4.0mg/L范围内符合比耳定律 ,表观摩尔吸光系数ε=6.0 5× 1 0 6 L·moL- 1·cm- 1,Sandell灵敏度S =0 .0 1 1 2ug·cm- 2 。方法用于人血清中蛋白质总量的测定 ,与经典的考马斯亮蓝G— 2 5 0方法结果一致。     

氯磺酚M与血清蛋白质相互作用的光度研究及分析应用

用于测定稀土等无机离子的显色剂氯磺酚M(chlorosulfophenol M),在pH 4.23的Britton-Robinson(B-R)缓冲介质中,能与生物活性物质血清蛋白质形成有色复合物,λmax为615nm,比试剂本身红移约63nm,表观摩尔吸光系数ε为4.34×105L.mol-1.cm-1,测定蛋白质的线性范围为0~100mg/L(牛血清白蛋白,BSA)。应用于临床中人血清样品总蛋白质的测定,结果与经典方法一致,而且操作简便、线性范围宽,重现性好,基本无干扰。     

理性设计提高β-葡萄糖醛酸苷酶的热稳定性

采用同源序列比对策略和脯氨酸效应的设计策略,以同源建模的三维结构为基础,结合定点突变技术,对重组产紫青霉β-葡萄糖醛酸苷酶(PGUS-E)进行理性设计,获得了2个热稳定性明显提高的突变体PGUS-E I130V和PGUS-E G280P,再将突变位点进行组合获得突变体PGUS-E I130V+G280P。相比PGUS-E,PGUS-E I130V、PGUS-E G280P和PGUS-E I130V+G280P在60℃下的半衰期T1/2分别比原始酶的23 min提高3.5倍,5倍和5.5倍,达到82 min,117 min和128min。突变体的动力学参数Kcat/Km值分别为1.534×107 mol-1·L·min-1,1.368×107mol-1·L·min-1和1.283×107 mol-1·L·min-1,与原始酶(1.316×107 mol-1·L·min-1)接近,对底物的亲和力基本不变。结果表明在蛋白质构象不稳定的区段中引入脯氨酸,以及在相应位置引入嗜热菌的氨基酸,均可提高蛋白质热稳定性。     

紫外光度法研究邻香草醛缩苯丙氨酸席夫碱与牛血清白蛋白的相互作用

采用紫外分光光度法研究了自制邻香草醛缩苯丙氨酸席夫碱试剂与牛血清白蛋白(BSA)的相互作用.确定最佳条件如下:支持电解质NaCl的浓度为0.15 mol·L-1、反应时间为55 min、席夫碱用量为3.0 mL、室温.在此条件下,席夫碱和牛血清白蛋白相互作用形成稳定的复合物,最大吸收波长为286.5 nm(与邻香草醛缩苯丙氨酸席夫碱试剂的最大吸收波长293 nm比较,紫移了6.5 nm)、结合比为30∶1、摩尔吸光系数为3.15×104 L·mol-1·cm-1,BSA浓度在0.01675～1.1136 g·L-1之间与吸光度具有良好的线性关系.考察了16种共存物质对分析测试的影响.据此测定绿豆芽中蛋白质含量,结果令人满意.     

偶氮胂羧与蛋白质作用的光谱性质及其分析应用研究

研究表明,在pH 1.5的Clark-Lubs(C-L)缓冲介质中,偶氮胂羧与多种蛋白质在室温下能迅速结合生成蓝色复合物,λmax为612nm,线性范围(HSA)为0~100mg/L,表观摩尔吸光系数为2.67×105L.mol-1.cm-1。研究了光谱性质及反应机理,试验了影响因素,在确定的最佳实验条件下,建立了以CAA为光谱探针的光度法测定人血清蛋白质的新方法。测定人血清样品中蛋白质的含量,与经典的考马斯亮蓝G-250法(CBB G-250)结果一致。     

氯磺酚N-蛋白质-TX-100体系的吸收光谱及其分析应用

在pH 3.09～4.16的Britton-Robinson缓冲介质中,有机试剂氯磺酚N能与生物大分子蛋白质形成紫红色复合物,λmax=620 nm,比试剂本身红移75 nm,摩尔吸光系数2.01×105 L·mol-1·cm-1,蛋白质在0～140μg·mL-1范围内遵循比尔定律,Tritton X-100存在反应灵...     

单扫描极谱法快速测定蛋白质的研究

在pH 4.7的HAc-NaAc缓冲溶液中,邻二氮菲与蛋白质相互作用,使邻二氮菲在-0.99 V(vs.SCE)处的还原峰电流下降,电流降低值与所加的蛋白质(人血清白蛋白、牛血清白蛋白、溶菌酶)的量在一定范围内呈线性关系,线性范围分别为2.0~22 mg/L,2.0~20 mg/L和4.0~26 mg/L;检测限分别为1.0 mg/L,1.0 mg/L,2.0mg/L。运用该方法测定了人血清中白蛋白的含量,结果满意。     

锌(Ⅱ) - 2,2''-联吡啶络合吸附波法测定血清白蛋白

在pH值6.3的HAc-NaAc介质中,血清白蛋白使锌(Ⅱ) - 2,2′-联吡啶络合物在-1.20 V(vs.SCE)处的络合吸附波还原峰电流降低,峰电流降低值与加入的牛血清白蛋白(BSA)或人血清白蛋白(HSA)的浓度在一定范围内呈线性关系.BSA和HSA的线性范围分别为0.5～40.0 mg·L-1、0.5～50.0 mg·L-1,检出限均为0.2 mg·L-1.应用该法测定了人血清样品中总蛋白含量,结果令人满意.     

维多利亚蓝B可见分光光度法测定氨曲南

在碱性Tris-盐酸介质中,维多利亚蓝B与氨曲南反应生成蓝色的二元离子缔合物,光谱曲线上出现1个明显的正吸收峰和1个明显的负吸收峰,最大正吸收波长位于620 nm,最大负吸收波长位于424 nm,线性范围均为0.1～8.7 mg/L,表观摩尔吸光系数(κ)分别为5.57×10~4 L·mol~(-1)·cm~(-1)(620 nm)和1.92×10~4 L·mol~(-1)·cm~(-1)(424 nm),检出限为0.08 mg/L (620 nm)和0.10 mg/L(424 nm)。若用双波长可见分光光度法测定,其表观摩尔吸光系数可达7.49×10~4 L·mol~(-1)·cm~(-1),检出限为0.045 mg/L [(620+424) nm]。以正吸收法为例,测定了市售药物中氨曲南的含量,回收率为98.0%～98.6%,相对标准偏差(RSD)为2.1%～2.4%(n=6)。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.