Glutathione peroxidase mimicry of diphenyl diselenide: Plausible contribution of proteins’ thiols

Organoseleniums are a class of compounds attracting attention across the globe owing to their Glutathione peroxidase(GPx)mimicry,which confers on them a strong antioxidant activity.Diphenyl diselenide(DPDS)is an Organoselenium whose GPx mimetic property has been suggested to rely on the oxidation of non-protein or protein thiols critical to the activities of some sulfhydryl enzymes.This study,therefore investigated the GPx mimic/antioxidant property of DPDS as well as the role of thiols of two key sulfhydryl enzymes,cerebral Na^(+)/K^(+)-ATPase(sodium pump)and hepatic delta-aminolevulinic acid dehydratase(δ-ALAD)in the GPx mimicry of DPDS.Albino Wistar rats were euthanized,and the liver and brain were removed and used to assay for the effect of DPDS on lipid peroxidation induced by two prooxidants[Fe2^(+)(10μM)and H2O2,(1 mM)]as well as the activities of the sulfhydryl enzymes.The results revealed that DPDS profoundly(P<0.05)counteracted Fe2^(+)and H2O2-induced lipid peroxidation in the rats’hepatic and cerebral tissues.Furthermore,the results of assay systems for lipid peroxidation and sodium pump revealed that DPDS inhibited Na^(+)/K^(+)-ATPase and lipid peroxidation in the brain tissue homogenates in the same reaction system.A similar result was obtained in the assay system for lipid peroxidation and hepaticδ-ALAD as DPDS simultaneously inhibited the enzyme’s activity and lipid peroxidation.This suggests that the GPx mimetic property of DPDS may be linked to the enzymes’loss of activity,which further validates the suggestions that the enzymes’inhibition,as well as the antioxidant action of DPDS,rely on the oxidation of critical thiols of the enzymes.However,the GPx mimicry of DPDS should be investigated in the presence of thiol-blocking or oxidizing agents in biological systems in order to further ascertain the role of protein thiols.

Fe(NO_3)_3·9H_2O/Fe(HSO_4)_3:An efficient reagent system for the oxidation of alcohols,thiols and sulfides in the absence of solvent

缺酸料液(NO3 ) 3 · 9 H2O/Fe (HSO4 ) 3 为白酒的氧化被用作一个有效试剂系统到他们的相应羰基化物。所有反应当溶剂不在时被执行在对高产率好。在一样的反应条件下面， thiols 和硫化物也分别地被变换成他们的相应二硫化物和 sulfoxides。

A Mechanism Study of a Novel Acid-Activatable Michael-Type Fluorescent Probe for Thiols

迈克尔增加通常作为 base-catalysed 反应被拿。然而，我们的综合的 2-(quinolin-2-ylmethylene ) malonic 酸(QMA ) 作为 Michael 类型 thiol 荧光灯探查在它的察觉到的反应是酸活跃的。在这工作，基于7-hydroxy-2-( quinolin-2-ylmethylene )上的理论上的计算和试验性的学习 malonic 酸，因为一个迈克尔领受人是 acid-activatable ，我们表明了那 QMA ，即，它在 pH 仅仅在答案工作< 7 ，并且更低答案的 pH 是，更高的反应 QMA 有。在碱的答案， malonate QMA [-2H+]2 不能与 RS 和 RSH 反应。相反， 2-(quinolin-2-ylmethylene ) malonic 酉旨(QME ) ， QMA 的酉旨，在它的察觉到的反应上揭示矛盾的 pH 效果，也就是说，它能在碱的答案然而并非在酸的答案察觉到 thiols，象正常 base-catalysed 迈克尔增加一样。从理论上的计算的激活热含量的价值在不同 pH 条件下面支持二根探针的上述察觉到的行为。在酸的答案， protonated QMA 向在它在中立、碱的答案的另外的电离状态上的 electrophilic 攻击是更高度反应的，能那么与低层的反应 RSH 反应。相反，在和 RSH (酸的解决方案) 的 QME 的相互作用有一个大精力障碍，并且有高度反应的 nucleophile RS 的 QME 的反应是低激活精力进程(在碱的解决方案) 。理论上的计算表明 QMA 的察觉到的反应经历 1,4 增加有中立 thiols (RSH ) 的过程，和为有 RS 的 QME 的察觉到的反应的一条 1,2 增加小径。因此， QMA 的察觉到的反应经由 1,2 增加是经由 1,4 增加，和正常 base-catalysed 迈克尔增加的 acid-catalysed 迈克尔增加。

Serum paraoxonase activity and protein thiols in patients with hyperlipidemia

Objective: In the present study we evaluated the paraoxonase activity and protein thiols level in south Indian population with newly diagnosed hyperlipidemia.Methods: The study was conducted on 55 newly diagnosed hyperlipidemic patients and 57 healthy controls.Serum paraoxonase activity and protein thiols were estimated by spectrophotometeric method and lipid profile by enzymatic kinetic assay method.Results: Serum paraoxonase activity,protein thiols and high density lipoprotein levels were low and total cholesterol,triglycerides and low density lipoprotein levels were high in patients with hyperlipidemia compared to healthy controls(P<0.01).Serum paraoxonase activity correlated positively with protein thiols and high density lipoprotein(P<0.01).Conclusion: Decreased paraoxonase activity and protein thiols were found in patients with hyperlipidemia.This may indicate the susceptibility of this population to accelerated atherogenesis and protein oxidation.

Relationship between serum copper and protein thiols in hyperlipidemic patients

Objective:To measure serum copper and protein thiols along with lipid profile in hyperlipidemic patients and to establish the relationship between serum copper,protein thiols and lipid profile parameters.Methods: The study group consisted of 26 newly diagnosed hyperlipidemic patients not associated with any other systemic diseases and 26 age and sex matched healthy controls.Fasting lipid profile was done by enzymatic method using automated analyzer.Serum copper and protein thiols were measured spectrophotometrically.Results: Serum copper and protein-SH levels were significantly decreased in cases(P<0.01,P<0.01) compared to controls.Serum copper correlated positively with protein thiols(r=0.800,P<0.01) and negatively with LDL cholesterol(r=-0.351 P<0.05).Conclusion: Serum copper and protein thiols were decreased in hyperlipidemia and they correlated positively indicating protective role of copper in preventing homocysteinylation of protein and hence in preventing atherosclerosis.

Association of bilirubin and protein thiols in relation to copper and ceruloplasmin in hyperbilirubinemic patients

Objective:Bilirubin is a double edged sword in biological system,acting as a toxic molecule and cytoprotectant.Unconjugated bilirubin is proved to show antioxidant activity in vitro and in vivo.In the current work we tried to know the relationship between both conjugated and unconjugated bilirubin with copper and protein thiols in patients with hyperbilirubinemia.Methods:Study was conducted on 56 hyperbilirubinemic cases and 56 healthy controls.Serum copper,ceruloplasmin,protein thiols,total bilirubin,conjugated and unconjugated bilirubin,unconjugated bilirubin/albumin ratio,total protein,albumin,AST,ALT and ALP were estimated.Results:There was significant increase in serum copper,total bilirubin,conjugated and unconjugated bilirubin,unconjugated bilirubin/albumin ratio,AST,ALT,and ALP,and decrease in serum ceruloplasmin,protein thiols,total protein,and albumin in hyperbilirubinemic cases when compared to healthy controls.Conjugated bilirubin correlated positively with liver enzymes AST and ALP,and negatively with protein thiols,total protein and albumin.Unconjugated bilirubin correlated positively with ALT.Protein thiols correlated negatively with copper and positively with ceruloplasmin,and also correlated negatively with liver enzymes like AST,ALT and ALP,and positively with total protein and albumin.Conclusion:Combination of elevated levels of trace elements like copper and availability of reducing agent like bilirubin may prove deleterious by generating free radicals.

Synthesis and <i>in Vitro</i>Biological Activities of 4,5-Disubstituted 1,2,4-Triazole-3-Thiols

Purpose: The triazole nucleus is an important part of the therapeutically interesting drug candidate as antimicrobial, analgesic, anticancer, anticonvulsant and anti-inflammatory agents. Methods: Therefore, in this study, twelve 4,5-disubstituted-1,2,4-triazole-3-thiols were synthesized by the reaction of substituted isothiocyanates and hydrazides using the common method of base catalysed intramolecular dehydrative cyclization of substituted thiosemicarbazides 3(a-f) and 4(a-f). The structures of these compounds were characterized by means of FT-IR, 1H-NMR, and elemental analysis data. All these compounds were screened for antibacterial, antioxidant, antitumor and cytotoxic activities. Results: Among these compounds: 5c, 5f and 6f were found active against gram positive cocci, the compounds 5a, 5b, 5d, 6a and 6f showed 85% free radical scavenging effect at 3 ppm when tested for antioxidant activity, 75% tumors inhibition was recorded using 5c, 5d and 6a and brine shrimps lethality assay declared 5a, 5b and 6d was 129.62 μg/ml, 161.577 μg/ml and 81.56 μg/ml respectively. Conclusion: Compounds carrying significant bioactivity can be further studied using animal models to establish their safety profile prior to initiating clinical trials.

The superhydrophobic sponge decorated with Ni-Co double layered oxides with thiol modification for continuous oil/water separation

In this paper, the superhydrophobic polyurethane sponge(SS-PU) was facilely fabricated by etching with Jones reagent to bind the nanoparticles of Ni-Co double layered oxides(LDOs) on the surface, and following modification with n-dodecyl mercaptan(DDT). This method provides a new strategy to fabricate superhydrophobic PU sponge with a water contact angle of 157° for absorbing oil with low cost and in large scale. It exhibits the strong absorption capacity and highly selective characteristic for various kinds of oils which can be recycled by simple squeezing. Besides, the as-prepared sponge can deal with the floating and underwater oils, indicating its application value in handling oil spills and domestic oily wastewater. The good self-cleaning ability shows the potential to clear the pollutants due to the ultralow adhesion to water. Especially, the most important point is that the superhydrophobic sponge can continuously and effectively separate the oil/water mixture against the condition of turbulent disturbance by using our designed device system, which exhibit its good superhydrophobicity, strong stability.Furthermore, the SS-PU still maintained stable absorption performance after 150 cycle tests without losing capacity obviously, showing excellent durability in long-term operation and significant potential as an efficient absorbent in large-scale dispose of oily water.

Assessment of thiol/disulfide homeostasis for prognostic follow-up of cholangiocarcinoma patients

Background:Cholangiocarcinoma(CCA)is a cancer type that builds in the bile ducts that carry digestive fluid,bile.These ducts connect the liver to the gallbladder and the small intestine.The disease is often diagnosed at an advanced stage,resulting in a low 5-year survival rate.This study aims to evaluate the concentrations of serum thiol/disulfide in CCA patients and healthy volunteers and investigate the association between oxidative activity and clinical and pathological characteristics in CCA patients.By examining the relationship between reduced thiol/disulfide measures and tumorigenesis of the disease,we can potentially identify an unfavourable prognosis in CCA patients.Methods:To assess the status of thiol/disulfide in the blood of Cholangiocarcinoma patients using a novel automated homeostasis assay,we recruited 55 individuals for this study(CCA patients,n=27;healthy volunteers,n=28).We measured the levels of serum total thiol(TT)(–SH+–S-S–),native thiol(NT)(–SH),and disulfide(DD)(–S-S–)in both the CCA group and the control group.Additionally,we calculated the ratio of thiol/disulfide(–SH/–S-S–).Results:We explored the relationship between oxidative activity and clinical and pathological characteristics in CCA patients.The study found no significant differences in age and sex between CCA patients and controls.NT and TT levels were higher in the control group compared to the CCA group.However,the disulfide level did not significantly differ between the two groups.Pearson's correlation matrix analysis revealed positive correlations between TT and NT levels and negative correlations between NT/TT%,DD level,and DD/TT%.Conclusion:Our findings suggest a statistical difference in serum thiol/disulfide parameters.As a marker of total oxidant status,thiol and disulfide levels have decreased in patients with CCA.However,no correlation was found between the tumour markers CEA and CA19-9 and thiol levels.A decrease in blood thiol and disulfide concentrations or the ratio of thiol to disulfide may indicate an increase in oxidative stress and decreased antioxidant capacity.As an indication of the prognosis of cholangiocarcinoma disease in the early period,it may be used to determine the effectiveness of medical interventions.The NT/TT%,disulfide/native thiol percentage,and DD/TT%ratios did not significantly change between the groups.Therefore,measuring serum thiol levels could be a helpful marker for assessing prognosis in the early stages of CCA.Nevertheless,further studies must validate these results and investigate the underlying mechanisms.

高效液相色谱联合2,2′-二硫二吡啶衍生反应测定人血清不同类型游离巯基及其与冠心病的关系分析

游离巯基对于心血管疾病的诊断和治疗具有潜在的临床预示价值,本研究建立了一种基于2,2′-二硫二吡啶衍生反应的高效液相色谱测定人血清游离巯基的分析方法,能够同时获得人血清中总游离巯基(Total-SH)、小分子化合物形态游离巯基(LMM-SH)、蛋白质形态游离巯基(P-SH)三者的含量。选用Agilent Eclipse XDB-C18色谱柱(150 mm×4.6 mm,5μm),以0.1%甲酸水溶液-0.1%甲酸乙腈溶液为流动相,在1 mL/min的流速下进行梯度洗脱,5 min内可实现良好的色谱峰基线分离,其中2-硫代吡啶酮色谱峰代表血清样本中总游离巯基含量,吡啶二硫衍生物色谱峰代表小分子化合物形态游离巯基含量,二者差值为蛋白质形态游离巯基含量。本研究对衍生反应条件进行了优化,并进行了方法学验证,结果表明,该方法线性关系良好,相关系数≥0.9994,线性范围为31.25~1000μmol/L,Total-SH和LMM-SH的检出限分别为2.61μmol/L和0.50μmol/L,定量限分别为8.71μmol/L和1.67μmol/L;加标回收率为91.1%~106.0%,日内精密度和日间精密度为0.4%~9.1%。使用本方法测定了714名志愿者的血清样本,总游离巯基浓度为376.60~781.12μmol/L,平均浓度为555.62μmol/L;小分子化合物形态游离巯基的浓度为36.37~231.65μmol/L,平均浓度为82.34μmol/L;蛋白质游离巯基浓度为288.36~687.74μmol/L,平均浓度为473.27μmol/L。Spearman相关性检验分析发现,血清游离巯基浓度与冠心病严重程度及常见临床生化指标存在密切关联。本研究提供了一种简便可靠的血清游离巯基分析方法,探索了其与冠心病的关系,为冠心病风险相关标志物的研究提供了新的参考指标。

苯并噻唑型功能化离子液体催化酮酚缩合反应的研究

以N-(3-磺酸基丙基)苯并噻唑、N-(3-磺酸基丙基)-2-巯基苯并噻唑为阳离子和硫酸氢根、对甲苯磺酸根为阴离子合成了4种功能化离子液体(ILs)。利用IR、1HNMR和MS对ILs进行结构表征;利用Hammett法和Ellman法对功能化离子液体的酸度和有效巯基含量等催化性能指标进行表征。同时,评价了该系列功能化离子液体在苯酚分别与环己酮、苯乙酮缩合反应中的催化效果,其中以阳离子结构中含有—SH、阴离子为对甲苯磺酸根的功能化离子液体对不同的酮底物均表现出良好的催化效果。考察反应温度对ILs催化酮酚缩合反应的影响,探究脂肪酮和芳酮的反应活性差异,结果表明,环己酮反应活性明显高于苯乙酮,且酚酮缩合反应是具有动力学和热力学控制特征的反应。基于实验结果分析了ILs催化酮酚缩合反应的可能机理。

蓖麻油基光敏树脂的合成及其UV-LED固化无影胶的性能

以蓖麻油、异佛尔酮二异氰酸酯、丙烯酸羟乙酯为原料,通过无溶剂法合成的一种蓖麻油基聚氨酯丙烯酸酯(CO-PUA)作为光敏单体。将自制的CO-PUA、活性稀释剂、硅烷偶联剂、附着力促进剂、光引发剂以及四(3-巯基丙酸)季戊四醇酯(PETMP)按比例混合制得一系列UV-LED固化无影胶,并考察了PETMP的添加量对无影胶性能的影响。结果表明:引入PETMP的UV-LED固化无影胶具有巯基-烯“点击化学”的反应特性,消除了氧阻的危害,无影胶固化完全。当PETMP的添加量为0.5 g时,具有最佳黏结性能,以有机玻璃-有机玻璃、有机玻璃-不锈钢、玻璃-不锈钢为搭接基材测得黏结拉伸剪切强度分别为2.44 MPa、5.06 MPa和5.70 MPa。

PEG-thiol修饰对金磁微粒胶体稳定性和抗吞噬能力的影响

目的探讨PEG-thiol修饰对GoldMag的磁学性能、体外悬浮稳定性和抗吞噬能力的影响。方法用PEG-thiol对GoldMag进行表面修饰,采用MR FSE序列T2W、GRE序列T2*W和T2mapping分别检测PEG-GoldMag和GoldMag的磁学性能;以Zeta电位仪检测两种纳米粒溶液的Zeta电位,紫外-可见光分光光度计检测两种纳米粒溶液不同时间点的吸光度,评估其悬浮稳定性。分别用两种纳米粒对小鼠单核巨噬细胞RAW 264.7进行体外标记,以普鲁士蓝染色检测两种纳米粒的细胞标记率,ICP-OES检测两种不同纳米粒标记的RAW 264.7细胞的细胞内铁含量,评估PEG修饰对GoldMag纳米粒体外抗吞噬能力的影响。结果GoldMag和PEG-GoldMag溶液的Zeta电位分别为-18.3mV和-39.5 mV。室温下静置100 min后,GoldMag和PEG-GoldMag溶液的相对吸光度分别为50%和88.5%;静置200min后两种溶液的相对吸光度分别为17%～18%和80%。两种纳米粒均能标记RAW 264.7细胞,GoldMag和PEG-GoldMag对RAW 264.7细胞的标记率分别为(85.3±2.1)%和(23.6±1.3)%。GoldMag和PEG-GoldMag标记的RAW264.7细胞的铁含量分别为(21.6±2.3)pg/细胞和(8.7±1.2)pg/细胞。在T2WI、T2*WI和T2mapping三种图像上,各浓度下PEG-GoldMag和GoldMag纳米粒凝胶的信号强度和T2值差异无统计学意义(P>0.05)。结论PEG-thiol修饰能显著改善GoldMag的悬浮稳定性和抗吞噬清除能力,且对其磁学性能无明显影响。

酱香型白酒酿造过程中挥发性硫醇类化合物的含量分布

挥发性硫醇类化合物是对酱香型白酒风味品质具有重要影响的一类“量微香大”风味组分,解析酱香型白酒酿造过程中挥发性硫醇类化合物的含量分布规律,对于酱香型白酒风味品质的科学控制具有重要意义。该研究采用4,4′-联吡啶二硫醚(4,4′-dithiodipyridine,DTDP)衍生化结合固相萃取(solid phase extraction,SPE)前处理,通过超高效液相色谱串联质谱(ultra-performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)技术,建立了酱香型白酒中9种代表性挥发性硫醇类化合物的检测方法,并对酱香型白酒酿造不同轮次(1~7轮次基酒)以及单一轮次不同时间(60 min内)蒸馏出的馏分酒中的挥发性硫醇类化合物的含量变化规律进行了解析。研究结果表明,3组不同轮次酱香型白酒中香气阈值极低的2-甲基-3-呋喃硫醇(含量范围:0.65~17.31μg/L)、糠硫醇(含量范围:16.96~26.09μg/L)等重要挥发性硫醇类化合物,随着酿造轮次的升高,其含量整体呈现一定上升的趋势。3层(上层、中层和下层)发酵酒醅蒸馏出来的馏分酒中挥发性硫醇的含量绝大部分呈现出先上升后下降的变化规律,部分硫醇含量变化稳定,蒸馏过程中的热反应促进了挥发性硫醇类化合物的生成。

用巯基-烯点击法制备1,2-聚丁二烯包覆的白炭黑及其对丁苯橡胶的增强

采用巯基-烯点击法制备出1,2-聚丁二烯包覆的疏水性白炭黑(Silica-PBs)。红外光谱和X射线电子能谱分析表明,Silica-PBs表面被1,2-聚丁二烯所包覆,并且还有多余的乙烯基。将Silica-PBs与丁苯橡胶(SBR)共混制备的硫化胶相比于使用硅烷偶联剂改性制得的硫化胶具有更优异的综合性能。通过橡胶加工分析仪和电子显微镜分析均可以发现,Silica-PBs在SBR中具有更好的分散状态。Silica-PBs可以在填料与橡胶分子链之间形成一条“缓冲带”,为填料在橡胶分子链滑移时提供一定的缓冲作用。动态力学性能测试结果显示,Silica-PBs相比于传统白炭黑提高SBR/Silica-PBs复合材料的动态力学性能8%以上,可以作为一种理想的绿色轮胎用填料。

新型重金属捕捉剂的除锑试验研究

巯基对锑具有较好的配位能力,因此研发人员将巯基嫁接至设计的分子骨架上,合成新型重金属捕捉剂(HMC-1)。试验采用HMC-1处理印染废水中的Sb(Ⅴ),研究不同HMC-1投加量、pH和共存离子等因素对Sb(Ⅴ)去除效果的影响。试验结果表明,最优条件下,HMC-1投加量为100 mg/L,pH为4.0±0.2,共存阴离子浓度为0 mg/L,Sb(Ⅴ)去除率可以达到92.33%,Sb(Ⅴ)浓度由3.00 mg/L降低到0.23 mg/L。印染废水处理后,出水满足《锡、锑、汞工业污染物排放标准》(GB 30770—2014)的要求。相比其他处理方法,该重金属捕捉剂对废水中Sb(Ⅴ)的去除效果好,处理速度快,投加量小且成本低,具有较好的市场应用前景。

形状记忆PCL/CB复合材料的制备及其光致弯曲变形行为

为了制备具有远程可控变形且性能优越的形状记忆聚合物,采用巯基-烯点击化学法制备了PCL/CB复合材料,并用FTIR、DSC、1 H NMR和DMA对复合材料的结构、热性能以及形状记忆特性等进行表征。结果表明:交联复合材料薄膜的热转变温度为50℃,且当预拉伸的复合材料薄膜受到100 mW/cm^(2)强度的激光照射时,CB颗粒吸收激光光子而产生光热转换且由于各向异性链松弛和应变能释放,致使上层薄膜在受到激光照射时,结晶熔融发生形状记忆效应而收缩,与此同时下层薄膜仍然处于玻璃态,上层薄膜的收缩力使PCL/CB复合材料薄膜朝着激光照射方向发生弯曲变形。同时,弯曲角度可以通过薄膜预拉伸应变量、激光照射时间以及薄膜厚度3个参数进行调控;当预拉伸应变为300%、薄膜厚度为0.4 mm时,最大弯曲角为164°。这种具备局部可编程行为的PCL/CB复合薄膜可为光响应SMP的变形模式提供新思路。

巯基改性蒙脱石对中国北方中碱性农田土壤镉钝化效果研究

农田土壤重金属污染是影响中国农产品环境质量安全的主要因素。钝化材料是修复农田重金属污染土壤的关键材料,研究开发出高效土壤重金属钝化材料,对于修复重金属污染农田和保障农产品食用安全非常重要。本文以蒙脱石为原材料,将巯基基团负载在其表面或层间制备巯基改性蒙脱石,借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和傅里叶红外光谱(FTIR)等技术表征巯基改性蒙脱石的特性,并开展室内土培试验,采用二乙三胺五乙酸浸提-火焰原子吸收分光光度法分析土壤镉的有效态,通过Tessier修正顺序七步提取法分析土壤镉的赋存形态。结果表明:蒙脱石经巯基改性后不仅新增了C-H、S-H共价键,而且增强了-OH和C=O化学键的活性,能与Cd2+发生巯基及羟基配位吸附。供试土壤添加巯基改性蒙脱石后,由于巯基配位吸附作用使土壤离子交换态镉转化为铁锰氧化物结合态,而增强的羟基配位吸附作用使其转化为碳酸盐结合态,结果使土壤中镉的赋存形态发生显著改变,离子交换态大幅减少,作物根系可吸收的土壤有效镉显著降低。添加1%、3%、5%巯基改性蒙脱石后,土壤有效镉分别降低21.92%、69.11%、82.90%;而作为对照组添加1%、3%、5%蒙脱石仅分别降低3.37%、1.80%、6.71%。蒙脱石经巯基改性后对土壤镉的钝化效果得到显著提升,土壤有效镉的降低幅度有随巯基改性蒙脱石添加量增加而提高的趋势。巯基改性蒙脱石对中国北方中碱性农田土壤镉的钝化效果显著,具有一定的参考应用价值。

Effect of Polyvinyl Alcohol with a Thiol End Group on the Properties of Polyacrylic Dispersions and Spray-dried Powder

The emulsion polymerization of highly shear-stable copolymer dispersions of methyl methacrylate and butyl acrylate were carried out using poly （vinyl alcohol） with a thiol end group （PVA-SH） as protective colloid. The dispersions can be transformed into corresponding redispersible powder via a spray dryingcooling process. On-line FT-IR monitoring shows that grafting polymer of PVA-g-PMMA was formed mainly at the stage-1 of the emulsion polymerization. TEM images show, the PVA-SH shell was fragmentary when adding SDS at initial stage and integrated when adding at particle growing or final stage. The particle size turns to be smaller when delayed adding SDS surfactant. Triethanolamine, a co-regulator of PVA-SH, controlled the M to 50 000-70 000 and reduced the PDI to 1.5-1.7. The acrylic dispersions with 0.8wt%-1.5wt% PVA-SH1 can be spray-dried into super dispersible polymer powder （SDPP）, which can easily disperse in water and form recon- stituted dispersions with an average particle size smaller than 1 micron.

Studies on the Thiol Components of Isolated Nuclei

The thiol components of the nonhistone proteins prepared from isolated nuclei from rat liver, regenerating liver and hepatoma 223 cells have been investigated after reaction with radio labelled N-ethylmaleimide and 5-5’-dithiobis-(2-nitrobenzoic acid) (DTNB). The labelled adducts formed were examined by isoelectric focusing analysis in polyacrylamide gel and the distribution of the radiolabels within sliced portions of the gels determined. In the case of the 14C labelled NEM adduct the label was found to be spread amongst numerous protein components within the gel however, in the case of the 35S labelled DTNB adducts, only a small proportion of the label was found in the protein material which was retained in the acidic isoelectric point (pI) region of the gel. The bulk of the 35S labelled adduct (56% - 60%) was found to have migrated into the anode solution (10 mM phosphoric acid). This could be adsorbed onto a hydrophobic resin (XAD2) resin and eluted with methanol. Gel filtration chromatographic analysis of this adduct material on BioGel P2, (exclusion limit 1500 daltons) showed low molecular weight components to be present. Slightly different patterns were obtained for these nuclei, each containing several 35S components with molecular weights greater than the Ellman reagent itself. These 35S labelled thiol components did not contain any protein, peptide or amino acid components indicating strongly that a novel species of thiols could be present in these nuclei bound within the non-histone protein matrices.