模拟过氧化物酶催化性能的研究

过氧化物酶(POD)能催化H₂O₂氧化一系列氢供体(DH₂)转化成氧化型供体(D)。氢供体可以是邻联二茴香胺、4-氨基安替比林和苯酚及某些染料隐色体等。这类反应不仅可提供检测H₂O₂的灵敏方法,还可与产生H₂O₂的其它酶反应系统联用,测定葡萄糖、半乳糖、氨基酸、尿酸及胆醇等生物物质。     

氨基醇杂多酸类离子液体催化环酮的Baeyer-Villiger氧化反应

合成了一系列氨基醇杂多酸类离子液体, 并将其用于催化环酮的Baeyer-Villiger氧化反应. 以2-庚基环戊酮为模板底物, H₂O₂为氧化剂, 探究了此类氨基醇杂多酸类离子液体的催化活性, 筛选出催化活性最高的催化剂为[Pro-ps]H₂PW₁₂O₄₀, 最佳反应条件: n(2-庚基环戊酮)∶n(催化剂)∶n(H₂O₂)=1∶0.03∶4, 反应温度40 ℃, 反应时间8 h, 无溶剂. 在最佳条件下, 2-庚基环戊酮的转化率为98.19%, 产物δ-十二内酯的选择性可达82.84%. 水相中的离子液体[Pro-ps]H₂PW₁₂O₄₀经干燥后可以重复使用. 经过5次循环使用后催化活性未见明显下降. [Pro-ps]H₂PW₁₂O₄₀还可用于催化其它多种环酮的Baeyer-Villiger氧化反应, 结果表明, 该催化剂具有良好的重复使用性和底物普适性.     

基于碳量子点过氧化物模拟酶的肌氨酸比色测定

以果皮为原料制备了水溶性碳量子点(CQDs), 透射电子显微镜分析表明其平均粒径为2.4 nm; 红外光谱分析证实CQDs表面富含含氧官能团. 所得CQDs可催化H₂O₂氧化3,3',5,5'-四甲基联苯胺(TMB)生成蓝色氧化产物(ox-TMB). 基于上述反应, 建立了测定H₂O₂的分析方法, 在pH=3.5, 温度40 ℃, TMB浓度为1.0 mmol/L及孵育时间15 min的条件下, 当H₂O₂浓度在5.0~100 μmol/L范围时, ox-TMB的吸光度随H₂O₂浓度的升高而线 性增强, 方法的检出限为3.0 μmol/L. 鉴于H₂O₂是肌氨酸氧化酶催化肌氨酸氧化的产物之一, 建立了CQDs催化H₂O₂氧化TMB间接测定肌氨酸的分析方法. 结果表明, 当肌氨酸浓度在0.5~350 μmol/L范围内时, 吸光度 与其浓度呈良好的线性关系, 方法的检出限为0.3 μmol/L; 将该方法应用于人体尿样的测定, 回收率为94%~99%.     

抗坏血酸提高稀土复合材料催化降解染料性能研究

本文以β-环糊精(CD)为载体,通过负载Fe₃O₄和稀土铈(Ce),制备了稀土复合材料Ce-Fe-CD,形成了可有效降解有机物的非均相芬顿反应Ce-Fe-CD/H₂O₂体系。为提高催化降解效果,本文用两种方式引入还原剂抗坏血酸(AA):(1)在非均相芬顿反应过程中直接投加AA,形成AA/Ce-Fe-CD/H₂O₂体系;(2)利用AA活化稀土复合材料,获得AA-Ce-Fe-CD复合材料,形成AA-Ce-Fe-CD/H₂O₂体系。实验结果表明,AA-Ce-Fe-CD/H₂O₂和AA/Ce-Fe-CD/H₂O₂对染料的降解率分别为86.9%和83.0%,比未使用AA时分别提高了34.4%和30.5%,且AA-Ce-Fe-CD/H₂O₂体系有更高的H₂O₂     

光照下自然水体生物膜产生H2O2及其对十二烷基苯磺酸钠降解的影响

通过模拟实验研究了不同活性的自然水体生物膜在光照条件下生成过氧化氢(H₂O₂)的反应. 并研究了光照对自然水体生物膜体系中十二烷基苯磺酸钠(SDBS)降解的影响, 结合无生物膜H₂O₂溶液中SDBS的降解实验, 验证了H₂O₂对SDBS降解的作用. 结果表明, 具有生物活性的生物膜可以生成H₂O₂, 而无活性和光合作用受到抑制的生物膜则不能生成H₂O₂; 光照条件下, 生物膜体系中SDBS的降解量明显高于无光照条件下的; 光照和Fe²⁺对H₂O₂降解SDBS有促进作用.     

Mn(II)-Fe(II)-MCF的制备及催化性能

以改性玉米苞叶纤维为载体(MCF),负载Mn(II)和Fe(II)制备了Mn(II)-Fe(II)-MCF复合材料,催化H₂O₂氧化水中染料。通过傅立叶变换红外/近红外成像系统和扫描电子显微镜对其结构和形貌进行表征。实验结果表明:当染料浓度为10 mg·L^-1,Mn(II)-Fe(II)-MCF用量为4 g·L^-1,H₂O₂初始浓度为1.56 mmol·L^-1,Mn(II)-Fe(II)-MCF对四种染料的催化效率明显不同。阳离子蓝X-GRRL(CBX-GRRL)降解效果最好,其次是甲基橙(MO)、次甲基蓝(MB)和罗丹明B(RhB)。对染料的氧化反应进行动力学分析,MO的降解反应为二级反应,CBX-GRRL、MB和RhB的降解反应均为一级反应。Mn(II)-Fe(II)-MCF适合催化氧化偶氮染料废水。     

活性炭纤维耦合柠檬酸铁在中性pH条件下活化双氧水降解染料

在环境催化领域,开发pH适应范围广的类芬顿催化剂一直是活跃而极具挑战性的研究课题. 采用活性炭纤维耦合柠檬酸铁制得耐pH的类芬顿催化纤维(Cit-Fe@ACFs),在pH值2～10的范围内Cit-Fe@ACFs均表现出优异的催化性能,有效拓宽了传统芬顿反应的pH适应范围;Cit-Fe@ACFs在中性条件下能快速活化H₂O₂催化降解活性染料、酸性染料、碱性染料等多种染料,并具有良好的重复使用性. 采用探针化合物正丁醇、苯醌,结合电子顺磁共振波谱(EPR)证明了Cit-Fe@ACFs/H₂O₂催化体系中的氧化活性种主要为羟基自由基(·OH)和超氧自由基(HO₂·),推测了其催化反应机理.     

有机农药异丙隆的级联生物降解体系的构建

构建了一个酶促氧化结合活性淤泥处理的级联生物降解有机农药异丙隆的体系.首先,建立了氯过氧化物酶（CPO）催化H₂O₂氧化降解异丙隆的酶处理体系.在最佳反应条件下,异丙隆的降解率可在10 min内达到100%.反应在室温下进行,pH=3.0,所需H₂O₂浓度为0.2 mmol/L,酶用量极少,仅7 nmol/L.降解体系高效、温和、绿色,无二次污染,极具应用潜力.CPO酶促氧化降解异丙隆的产物用HPLC-MS测定,并进一步根据主要产物推测了降解的途径.结果表明,异丙隆经CPO催化H₂O₂氧化处理后,被分解成较小的4-异丙基苯胺和4-乙基苯胺苄基正离子碎片分子.如果将CPO-H₂O₂酶促氧化作为一种前处理手段,后续与活性淤泥微生物降解过程结合,通过这种二级处理方法可实现含异丙隆污水的化学需氧量（COD）的有效去除,达到含异丙隆污水深度治理的目的.进一步以绿藻Chlorella pyrenoidosa的生长抑制率为评价指标对异丙隆酶催化氧化降解的产物进行了毒性评估,结果表明,随着底物降解率的逐渐增大,降解产物对绿藻的生长抑制率逐渐减小,说明经酶法降解后得到的产物与异丙隆相比毒性降低.     

活性炭催化过氧化物高级氧化技术降解水中有机污染物*

活性炭（AC）能够催化过氧化氢(H₂O₂）释放出强氧化性的羟基自由基•OH。过二硫酸盐（PS）与H₂O₂结构上相似,因此PS也有可能被AC催化产生强氧化性的硫酸根自由基SO4−•。AC催化无机过氧化物（H₂O₂或PS）将发展成为一类新型高级氧化技术。AC催化H₂O₂联合体系包括AC/H2O2,AC/Fenton,AC/H₂O₂/紫外光,,AC/H₂O₂/微波,AC/湿式H₂O₂氧化;AC催化AC/PS联合体系包括 AC/PS,AC/PS/金属离子, AC/PS/ 微波。AC过氧化联合体均可高效降解水中有机污染物。本文在首次综述AC/过氧化物联合体系处理有机污染物研究现状的基础上,分析了AC和过氧化物的相互作用,并对该类高级氧化技术的发展前景进行了展望。     

过氧化氢原位生成驱动过氧合酶催化反应研究进展

C—H键的选择性催化氧官能团化反应是有机化学中非常具有挑战的一类反应.与贵金属络合物催化剂相比,生物酶在选择性和活性等方面表现出一定优势.其中,过氧合酶(peroxygenase)作为近年来研究热点,能够直接利用过氧化氢(H₂O₂)作为共底物催化C—H键的氧官能团化反应.过氧合酶结合了P450单加氧酶的催化多功能性且无须依赖辅酶及其再生体系,因此在有机合成中引起越来越多的重视.但是,过氧合酶在实际应用中存在一个瓶颈:即过氧合酶对其催化所必须的H₂O₂浓度敏感,当反应体系中H₂O₂浓度过高时,会引起过氧合酶中的亚铁血红素氧化分解,从而导致酶失活.为突破该瓶颈,调控反应体系中H₂O₂的浓度对于高效应用过氧合酶来说格外重要.概括了近年来多种原位生成H₂O₂驱动过氧合酶催化的方法.从酶催化、光催化、电催化原位生成H₂O₂角度出发,全面...     

Mechanistic studies on the effect of veratryl alcohol on the lignin peroxidase catalyzed oxidation of pyrogallol red in reversed micelles

The lignin peroxidase (LiP) catalyzed oxidation of pyrogallol red (PR) in the absence and presence of veratryl alcohol (3,4-dimethoxybenzyl alcohol, VA) was carried out in bis (2-ethylhexyl) sulfosuccinate sodium (AOT)/ polyoxyethylene lauryl ether (Brij30) reversed micelles to elucidate the role of VA. Results indicated that VA could accelerate the LiP catalyzed oxidation of PR, especially at low H₂O₂ concentrations. Unlike in bulk aqueous medium, the protection of LiP by VA in the present medium was relatively unsubstantial, even at high H₂O₂ concentrations. Analysis of data from a series of experiments showed that the enhancement of the PR oxidation caused by VA was mainly due to the indirect oxidation of PR by VA^+∙ from the LiP catalyzed oxidation of VA. It was also found that at the same protector concentration (40 μM), VA (the physiological substrate of LiP) was less effective than PR (a phenolic compound) in protecting LiP from the H₂O₂ derived inactivation. This novel phenomenon deserves further study.      

Catalytic performance of lignin peroxidase in a novel reverse micelle

To enhance the catalytic activity of lignin peroxidase (LiP) in a reverse micelle, a synthesized two-tail nonionic surfactant N-gluconyl glutamic acid didecyl ester (GGDE) was used to formulate a novel reverse micelle. Based on the LiP catalyzed oxidation of veratryl alcohol (VA) in this novel GGDE/TritonX-100-cyclohexane-H(2)O reverse micelle, the effects of the size of the reverse micelle, the buffer pH, and the concentration of H(2)O(2) on the catalytic activity of LiP were investigated. Under the optimized conditions, the catalytic efficiency of LiP in the GGDE/TritonX-100 reverse micelle was 40 times higher than that in the AOT reverse micelle. The full expression of catalytic activity of LiP in this medium was mainly due to the lack of electrostatic interaction between LiP and the head group of GGDE and TritonX-100 and to the size fit between LiP and the inner water cavity of the reverse micelle.     

Kinetics of the H2O2-dependent ligninase-catalyzed oxidation of veratryl alcohol in the presence of cationic surfactant studied by spectrophotometric technique

The kinetics of ligninase-catalyzed oxidation of veratryl alcohol (VA) by H(2)O(2) in the aqueous medium containing cationic surfactant cetyltrimethylammonium bromide (CTAB) has been investigated using spectrophotometric technique. Steady-state kinetic studies at different concentrations of CTAB indicate that the reaction follows a ping pong mechanism and the mechanism always holds but the kinetic parameters vary with CTAB concentrations. CTAB is a weak inhibitor for ligninase; it lowers the maximum initial velocity. CTAB also causes the Michaelis constant of H(2)O(2) to decrease dramatically and that of VA to increase markedly. Based on the changes in kinetic parameters of the enzyme-catalyzed reaction at different CTAB concentrations (lower than, near to and larger than its critical micelle concentration) and the effects of the CTAB monomer and the micelles on the spectra of VA and its corresponding aldehyde, a conclusion could be made that modification of the enzymatic protein by the surfactant monomer should be responsible for the above-mentioned results.     

纳米孔洞金属-有机骨架催化氧化苯甲醇动力学研究

具有纳米孔洞的金属-有机骨架材料Cu3（BTC）2（H2O）3为催化剂,过氧化氢为氧化剂,利用紫外可见光谱研究其催化氧化苯甲醇生成苯甲醛的催化反应动力学行为,系统地讨论了纳米孔洞金属-有机骨架材料的催化动力学。研究结果表明,随着反应介质的pH、催化剂与反应底物的摩尔比和反应温度的升高,准一级反应速率常数kobsd也会随...     

Heterogeneous oxidation of cyclohexanone catalyzed by TS-1:Combined experimental and DFT studies

The reaction mechanism of the oxidation of cyclohexanone catalyzed by titanium silicate zeolite TS-1 using aqueous H2O2 as the oxidant was investigated by combining density function theory (DFT) calculations with experimental studies. DFT calculations showed that H2O2 was adsorbed and activated at the tetrahedral Ti sites. By taking into account the adsorption energy, molecular size, steric hindrance and structural information, a reaction mechanism of Baeyer-Villiger oxidation catalyzed by TS-1 that involves the activation of H2O2 was proposed. Experimental studies showed that the major products of cyclohexanone oxidation by H2O2 catalyzed by a hollow TS-1 zeolite wereε-carprolactone, 6-hydroxyhexanoic acid, and adipic acid. These products were analyzed by GC-MS and were in good agreement with the proposed mechanism. Our studies showed that the reaction mechanism on TS-1 zeolite was different from that on Sn-beta zeolite.     

用H2O2氧化苯乙烯合成苯甲酸

摘要：以30％H2O2做为氧化剂,钨酸钠与含O双齿有机配体(草酸)形成的络合物为催化剂,在无有机溶剂、无相转移剂的条件下,研究了苯乙烯氧化制苯甲酸的反应。研究结果表明,最佳反应条件为：苯乙烯100．0mmol,n(钨酸钠)：n(草酸)：n(苯乙烯)：n(30％H2O2)=2．0：3．2：100．0：440．0,于92℃反应24h,苯甲酸收率98．6％。用GC—MS跟踪了氧化过程中4种主要物质苯乙烯、1-苯基邻二醇、羟基苯乙酮及苯甲酸含量随反应时间的变化关系,提出了其主要氧化机理为苯乙烯经过环氧化反应、水解生成生成1-苯基邻二醇,1-苯基邻二醇再氧化为羟基苯乙酮、最后氧化为苯甲酸。     

Heteropolymolybdate as a New Reaction-controlled Phase-transfer Catalyst for Efficient Alcohol Oxidation with Hydrogen Peroxide

Aldehydes are very important raw materials or intermediates, which have widespread applications in the perfumery, pharmaceutical, dyestuff and agrochemical industries1. Oxidation of alcohol is one of the most frequently used synthetic reactions in the lab…     

Lignin peroxidase-catalyzed oxidation of nonphenolic trimeric lignin model compounds: fragmentation reactions in the intermediate radical cations

The H(2)O(2)-promoted oxidations of the two nonphenolic beta-O-aryl lignin model trimers 1 and 2, catalyzed by lignin peroxidase (LiP) at pH = 3.5, have been studied. The results have been compared with those obtained in the oxidation of 1 and 2 with the genuine one-electron oxidant potassium 12-tungstocobalt(III)ate. These models present a different substitution pattern of the three aromatic rings, and by one-electron oxidation, they form radical cations with the positive charge, which is localized in the dialkoxylated ring as also evidenced by a pulse radiolysis study. Both the oxidations with the enzymatic and with the chemical systems lead to the formation of products deriving from the cleavage of C-C and C-H bonds in a beta position with respect to the radical cation with the charge residing in the dialkoxylated ring (3,4-dimethoxybenzaldehyde (5) and a trimeric ketone 6 in the oxidation of 1 and a dimeric aldehyde 8 and a trimeric ketone 9 in the oxidation of 2). These products are accompanied by a dimeric aldehyde 7 in the oxidation of 1 and 4-methoxybenzaldehyde (10) in the oxidation of 2. The unexpected formation of these two products has been explained by suggesting that 1.+ and 2.+ can also undergo an intramolecular electron transfer leading to the radical cations 1a.+ and 2a.+ with the charge residing in a monoalkoxylated ring. The fast cleavage of a C-C bond beta to this ring, leading to 7 from 1.+ and to 10 from 2.+, is the driving force of the endoergonic electron transfer. A kinetic steady-state investigation of the LiP-catalyzed oxidation of the trimer 2, the dimeric model 1-(3,4-dimethoxyphenyl)-2-phenoxy-1-ethanol (4), and 3,4-dimethoxybenzyl alcohol (3) has indicated that the turnover number (k(cat)) and the affinity for the enzyme decrease significantly by increasing the size of the model compound. In contrast, the three substrates exhibited a very similar reactivity toward a chemical oxidant [Co(III)W]. This suggests a size-dependent interaction of the enzyme with the substrate which may influence the efficiency of the electron transfer.     

对甲苯磺酸/活性炭/双氧水体系选择氧化苯乙烯生成苯甲醛(英文)

以双氧水为氧化剂,研究了对甲苯磺酸和活性炭体系选择氧化苯乙烯生成苯甲醛反应性能。考察了反应时间、温度、催化剂用量、苯乙烯和双氧水摩尔比等对苯乙烯选择氧化性能的影响.结果表明,对甲苯磺酸和活性炭的用量和用量比是一个重要因素,但对甲苯磺酸的酸性对氧化反应活性影响不大.对甲苯磺酸和双氧水相互作用,经非自由基过程氧化苯乙烯.通过分解双氧水产生氢氧自由基,活性炭显著提高对甲苯磺酸和双氧水体系氧化苯乙烯活性.在惰性或还原气氛中高温处理活性炭能降低其表面含氧基团数量,增加碱性,有效分解双氧水,产生相对较多的OH自由基.与未处理的活性炭相比,高温处理的活性炭进一步提高了对甲苯磺酸和双氧水体系氧化苯乙烯活性,但降低了苯甲醛选择性.经磺化,在活性炭表面引入的–SO_3H基团比含氧基团(–OH,–COOH)更有效与双氧水作用氧化苯乙烯.     

Activity Regulation of Lignin Peroxidase from Phanerochaete chrysosporium in Nonionic Reversed Micellar Medium

The activity of lignin peroxidase (LIP) in reversed micelles of polyoxy ethylene laurylether (Brij30) changed with the molar ratio of water to the surfactant and the denaturant concentration of guanidinium chloride. At low water contents the activity of LiP could be enhanced by the denaturant at moderate concentration. This phenomenon, together with the spectral characteristics of the intrinsic fluorescence of LiP, suggested that the conformation of the active center of LIP was flexible.