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31.
32.
原卟啉原氧化酶是叶绿素与亚铁原卟啉合成之前四吡咯生物合成途径中最后一种关键酶,此种酶是许多除草剂的作用靶标;原卟啉原氧化酶抑制除草剂施用后导致植物细胞过氧化及光下组织白化。介绍了原卟啉原氧化酶抑制除草剂的一个重要新品种—苯嘧磺草胺的特性及其使用。 相似文献
33.
Comparison of biochemical properties and thermal inactivation of membrane‐bound polyphenol oxidase from three apple cultivars (Malus domestica Borkh) 下载免费PDF全文
Fang Liu Qianyun Han Yuanying Ni 《International Journal of Food Science & Technology》2018,53(4):1005-1012
A comparative study of the properties of membrane‐bound polyphenol oxidase (mPPO) from three apple cultivars, namely Red Fuji (FJ), Granny Smith (GS) and Golden Delicious (GD), was carried out for the first time. Data indicate that mPPOs from three cultivars exhibit significantly different properties. GS mPPO had the strongest affinity to catechol, but FJ mPPO had the highest maximum velocity. Red Fuji (FJ) mPPO had the significantly higher activity than those of GD and GS mPPOs. Red Fuji (FJ) mPPO had the highest activity at pH 8.00, while GD and GS mPPOs at 4.50 and 7.50–8.00, respectively. Red Fuji (FJ) mPPO was more stable than GD and GS mPPOs over the pH range of 5.0–8.5. The optimal temperature for GS mPPO was within 70–75 °C, which is higher than those for mPPOs from FJ and GD. Thermal inactivation of the three mPPOs followed a first‐order kinetic model with different inactivation kinetic parameters. 相似文献
34.
Kimiyoshi Ichida Yoshihiro Amaya Ken Okamoto Takeshi Nishino 《International journal of molecular sciences》2012,13(11):15475-15495
Xanthine oxidoreductase (XOR) catalyzes the conversion of hypoxanthine to xanthine and xanthine to uric acid with concomitant reduction of either NAD+ or O2. The enzyme is a target of drugs to treat hyperuricemia, gout and reactive oxygen-related diseases. Human diseases associated with genetically determined dysfunction of XOR are termed xanthinuria, because of the excretion of xanthine in urine. Xanthinuria is classified into two subtypes, type I and type II. Type I xanthinuria involves XOR deficiency due to genetic defect of XOR, whereas type II xanthinuria involves dual deficiency of XOR and aldehyde oxidase (AO, a molybdoflavo enzyme similar to XOR) due to genetic defect in the molybdenum cofactor sulfurase. Molybdenum cofactor deficiency is associated with triple deficiency of XOR, AO and sulfite oxidase, due to defective synthesis of molybdopterin, which is a precursor of molybdenum cofactor for all three enzymes. The present review focuses on mutation or chemical modification studies of mammalian XOR, as well as on XOR mutations identified in humans, aimed at understanding the reaction mechanism of XOR and the relevance of mutated XORs as models to estimate the possible side effects of clinical application of XOR inhibitors. 相似文献
35.
Danuta Wojcieszyńska Katarzyna Hupert-Kocurek Urszula Guzik 《International journal of molecular sciences》2012,13(12):16751-16768
Statistical studies have demonstrated that various agents may reduce the risk of cancer’s development. One of them is activity of flavin-dependent enzymes such as flavin-containing monooxygenase (FMO)GS-OX1, FAD-dependent 5,10-methylenetetrahydrofolate reductase and flavin-dependent monoamine oxidase. In the last decade, many papers concerning their structure, reaction mechanism and role in the cancer prevention were published. In our work, we provide a more in-depth analysis of flavin-dependent enzymes and their contribution to the cancer prevention. We present the actual knowledge about the glucosinolate synthesized by flavin-containing monooxygenase (FMO)GS-OX1 and its role in cancer prevention, discuss the influence of mutations in FAD-dependent 5,10-methylenetetrahydrofolate reductase on the cancer risk, and describe FAD as an important cofactor for the demethylation of histons. We also present our views on the role of riboflavin supplements in the prevention against cancer. 相似文献
36.
Supatcha Kubglomsong Chockchai Theerakulkait 《International Journal of Food Science & Technology》2014,49(2):551-557
Effect of rice bran protein extract (RBPE) on enzymatic browning inhibition in potato puree was studied by colour measurement and polyphenol oxidase (PPO) inhibition. RBPE inhibited browning in potato puree and showed a higher per cent potato PPO inhibition at pH 4.0 and 5.0 than those at pH 3.0, 6.0 and 7.0 (P ≤ 0.05). RBPE heated to 40 and 60 °C had browning inhibition in potato puree and per cent potato PPO inhibition at a similar extent to unheated RBPE (P > 0.05). Browning inhibition and per cent potato PPO inhibition of RBPE were decreased when it was heated to 80 °C (P ≤ 0.05). RBPE inhibited browning in potato puree higher than 5, 10 and 20 mm ascorbic acid and 5 and 10 mm citric acid (P ≤ 0.05). Regarding the kinetics study, RBPE exhibited a mixed‐type inhibition for potato PPO. Therefore, RBPE has a potential to be used as a natural antibrowning agent in the potato industry. 相似文献
37.
Optimization of pulsed electric field pretreatment parameters for preserving the quality of Raphanus sativus 总被引:1,自引:0,他引:1
Pulsed electric field (PEF) pretreatment can increase the drying rate of produce, but preserving product quality while minimizing energy consumption and maintaining food quality is a significant challenge. The goal of this study was to determine optimal PEF parameters for pretreatment of Raphanus sativus (radish) prior to the drying process. The effects of pulse intensity, treatment time, and pulse number on the drying rate, vitamin C (Vc) content, and ascorbic acid oxidase activity of R. sativus were characterized. Optimal PEF pulse parameter values were determined through quadratic orthogonal regression tests followed by multi-objective nonlinear optimization. The optimal PEF pulse parameters for pretreatment of R. sativus were: pulse intensity, 1446 V · cm?1; reaction time, 28 μs; and pulse number, 87. This study provides reference values to guide application of PEF pretreatment in R. sativus processing. 相似文献
38.
Exploration of a Library of 3,4‐(Methylenedioxy)aniline‐Derived Semicarbazones as Dual Inhibitors of Monoamine Oxidase and Acetylcholinesterase: Design,Synthesis, and Evaluation 下载免费PDF全文
A library of 3,4‐(methylenedioxy)aniline‐derived semicarbazones was designed, synthesized, and evaluated as monoamine oxidase (MAO) and acetylcholinesterase (AChE) inhibitors for the treatment of neurodegenerative diseases. Most of the new compounds selectively inhibited MAO‐B and AChE, with IC50 values in the micro‐ or nanomolar ranges. Compound 16 , 1‐(2,6‐dichlorobenzylidene)‐4‐(benzo[1,3]dioxol‐5‐yl)semicarbazide presented a balanced multifunctional profile of MAO‐A (IC50=4.52±0.032 μm ), MAO‐B (IC50=0.059±0.002 μm ), and AChE (IC50=0.0087±0.0002 μm ) inhibition without neurotoxicity. Kinetic studies revealed that compound 16 exhibits competitive and reversible inhibition against MAO‐A and MAO‐B, and mixed‐type inhibition against AChE. Molecular docking studies further revealed insight into the possible interactions within the enzyme–inhibitor complexes. The most active compounds were found to interact with the enzymes through hydrogen bonding and hydrophobic interactions. Additionally, in silico molecular properties and ADME properties of the synthesized compounds were calculated to explore their drug‐like characteristics. 相似文献
39.
The last decade has seen a growing interest in hybrid electrically conducting nanocomposites. This article aims to provide a detailed overview of the present status of research in carbon nanotube–polyaniline (CNT/PANI) composites, from processing to structural and property evaluations. CNT/PANI are synthesized by electrochemical and chemical processing. When chemical methods are used, the main challenge is to obtain processable CNT/PANI in the emeraldine salt (ES) form composites. Stable dispersions of ES–CNT in organic media are prepared using the post doping method, inverse emulsion polymerization, or ex situ polymerizations. On the contrary, stable water dispersions of CNT/ES are prepared using hydrophilization of a preformed CNT/ES composite, direct synthesis of micelle–CNT hybrid templates, interfacial polymerization, covalent functionalization of CNT with a water soluble polymer, or using electrostatic interactions between two oppositely charged ES and CNT aqueous colloids. Moreover, the strategies for the synthesis of ternary CNT/PANI composites incorporating noble metal nanoparticles, metal oxide, or graphene sheets are also presented and analyzed in depth. Finally, we give a review of potential applications, including chemical sensors, capacitors, fuel cells and electronic devices. 相似文献
40.
Dendrimers are novel three dimensional, hyperbranched globular nanopolymeric architectures. Attractive features like nanoscopic size, narrow polydispersity index, excellent control over molecular structure, availability of multiple functional groups at the periphery and cavities in the interior distinguish them amongst the available polymers. Applications of dendrimers in a large variety of fields have been explored. Drug delivery scientists are especially enthusiastic about possible utility of dendrimers as drug delivery tool. Terminal functionalities provide a platform for conjugation of the drug and targeting moieties. In addition, these peripheral functional groups can be employed to tailor-make the properties of dendrimers, enhancing their versatility. The present review highlights the contribution of dendrimers in the field of nanotechnology with intent to aid the researchers in exploring dendrimers in the field of drug delivery. 相似文献