ANALYTICAL CHEMISTRY
·
2024
·
IF 6.7
Huiping Yang,Yinning Lin,Qian Mo,Zhaoquan Li,Fan Yang,Xinchun Li
Enzyme-mediating biotransformations commonly occur in micro- and nanospace, which is crucial to maintain the essential biochemical processes and physiological functions in living systems. Probing enzyme-catalytic reactions in a biomimetic fashion remains challenging due to the lack of competent tools and methodology. Here, we show that studying enzymatic reaction kinetics can be readily achieved by a well-designed solid-state nanopore. Using tyrosine as a classical substrate, we quantitatively characterize the catalytic activity of tyrosinase (TYR) and tyrosine decarboxylase (TDC) in a nanoconfined space. Tyrosine was first immobilized in the nanopipette, wherein the active sites of tyrosine were left unoccupied. When successively exposed to TYR and TDC, a two-step cascade reaction can spontaneously take place. In this process, the surface wettability and charge of the nanopipette stemming from the catalytic products can sensitively regulate ion transport and ionic current rectification behavior, which were monitored by ionic current signal. In this biomimetic scenario, we obtained the enzymatic reaction kinetics of monophenyl oxidase that were not previously actualized in the conventional macroenvironment. Significantly, TYR showed higher enzyme activity, with a Km value of 1.59 mM, which was lower than that measured in a free and open space (with a Km of 3.01 mM). This suggests that tyrosine should be the most appropriate substrate of TYR, thus improving our understanding of tyrosine-associated biochemical reactions. This work offers an applicable technical platform to mimic enzyme-mediated biotransformations and biometabolisms.
研究领域:
生物技术
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生物化学
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纳米技术
·
酶学
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产品关联
DOI
PubMed
高影响因子
BIOSENSORS & BIOELECTRONICS
·
2014
·
IF 6.451
Juying Hou,Jing Dong,Haishuang Zhu,Xue Teng,Shiyun Ai,Minglin Mang
In this paper, a simple and sensitive fluorescent sensor for methyl parathion is developed based on l -tyrosine methyl ester functionalized carbon dots (Tyr-CDs) and tyrosinase system. The carbon dots are obtained by simple hydrothermal reaction using citric acid as carbon resource and l -tyrosine methyl ester as modification reagent. The carbon dots are characterized by transmission electron microscope, high resolution transmission electron microscopy , X-ray diffraction spectrum, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The carbon dots show strong and stable photoluminescence with a quantum yield of 3.8%. Tyrosinase can catalyze the oxidation of tyrosine methyl ester on the surface of carbon dots to corresponding quinone products, which can quench the fluorescence of carbon dots. When organophosphorus pesticides (OPs) are introduced in system, they can decrease the enzyme activity , thus decrease the fluorescence quenching rate. Methyl parathion, as a model of OPs, was detected. Experimental results show that the enzyme inhibition rate is proportional to the logarithm of the methyl parathion concentration in the range 1.0×10 −10 –1.0×10 −4 M with the detection limit ( S / N =3) of 4.8×10 −11 M. This determination method shows a low detection limit, wide linear range, good selectivity and high reproducibility. This sensing system has been successfully used for the analysis of cabbage, milk and fruit juice samples.
研究领域:
分析化学
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环境科学
·
农药检测
✓ 已验证
DOI
高影响因子
ANALYTICAL BIOCHEMISTRY
·
2018
·
IF 2.275
Xiao-Ling Tang,Hui Suo,Ren-Chao Zheng,Yu-Guo Zheng
Tyrosine phenol-lyase (TPL) naturally catalyzes the reversible β-elimination of l -tyrosine to phenol, pyruvate and ammonium. With its reverse reaction (synthetic activity), l -tyrosine and its derivatives could be synthesized with high atom economy, which are widely used in pharmaceutical industries . In this study, a high-throughput screening method for synthetic activity of TPL was developed. One of the substrate, sodium pyruvate was found to react with salicylaldehyde under alkali condition, forming a yellow color compound. The concentration of sodium pyruvate can be quantified according to the absorbance of the colorimetric compound at wavelength of 465 nm and the activity of TPL could be screened according to the decrease of the absorbance. After optimization of the colorimetric reaction conditions, the established high-throughput screening method was successfully used for screening of TPL with enhanced activity for l -DOPA synthesis. The confirmed sensitivity and accuracy demonstrated the feasibility and application potential of this screening method.
研究领域:
生物化学
·
制药工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
AQUACULTURE
·
2024
·
IF 3.9
Kunyin Jiang,Hong Yu,Lingfeng Kong,Shikai Liu,Shaojun Du,Qi Li
The visually appealing shell colours and intricate patterns of shellfish not only attract consumers but also enhance their economic value. Understanding the inheritance pattern of shell colour and the molecular mechanism of pigmentation is highly important for enhancing breeding efficiency. This study involved the identification of a tyrosine hydroxylase gene ( CgTH ) and the investigation of its function in the metabolism of tyrosine and pigmentation in Pacific oysters. CgTH contains a conserved Biopterin_H domain that consists of a binding site for iron atoms and a binding site for tetrahydrobiopterin (BH4). Quantitative PCR (qPCR) and immunofluorescence analysis revealed that the expression of CgTH was higher in the mantle of black shell oysters in comparison to the white strain. The in vitro and in vivo experiments confirmed that Cg TH is involved in tyrosine metabolism through the catalysis of the conversion of L-tyrosine to L-DOPA. In order to examine its functions in melanin synthesis in oysters, 3-Iodo-L-tyrosine (3-IT) treatment, RNA interference (RNAi), and L-DOPA treatment assays were conducted. The results of our study showed that 3-IT effectively inhibited Cg TH activity, leading to a suppression of tyrosine metabolism. Knockdown of Cg TH hindered the cAMP-CREM-MITF axis and decreased pigmentation. On the other hand, L-DOPA stimulated melanin production through cAMP signaling and counteracted the inhibitory effects of 3-IT on the metabolism of tyrosine. These data indicated that there may be a feedback loop involving Cg TH and the cAMP-CREM-MITF axis that regulates tyrosine metabolism and melanogenesis in Pacific oysters. This study enhances our understanding of the molecular mechanism that governs oyster pigmentation and offers a possible molecular indicator for the targeted breeding of particular strains of Pacific oysters ( Crassostrea gigas ).
研究领域:
海洋生物学
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分子生物学
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遗传学
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水产养殖
✓ 已验证
DOI
高影响因子
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY
·
2021
·Vol. 85
·期 7
·1697-1705
·
IF 2.043
Chen Jianmin,Ran Mengnan,Wang Meixia,Liu Xinying,Liu Siwan,Yu Yue
The related structure–activity relationships of cinnamic acid and its derivates have not been studied in details yet. Herein, antityrosinase and antioxidant activities of 18 compounds were evaluated. The results demonstrated that the substituents on the phenyl ring of cinnamic acid led to the enhancement of the inhibition on monophenolase and the weakening of the inhibition on diphenolase. Among these tested compounds, 9 was first discovered as a tyrosinase inhibitor in a reversible competitive manner with IC50 value of 68.6 ± 4.2 µm. Docking results demonstrated 9 located into the catalytic center of tyrosinase. Antioxidant assay indicated that only 1 hydroxyl group on the phenyl ring was not enough to possess the radical scavenging activity, and the number of hydroxyl groups may be more important. This study will be helpful in the development of new cinnamic acid derivates as tyrosinase inhibitors and antioxidants with higher efficacy.
研究领域:
药理学
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生物化学
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分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MOLECULES
·
2020
·Vol. 25
·期 2
·344
·
IF 3.267
Limin Qu,Ke Song,Qi Zhang,Jie Guo,Juan Huang
Tyrosinase inhibitors with excellent inhibitory activities and lower side effects have promising applications in the fields of medicine, agriculture, food sciences and cosmetics. In this study, a method for simultaneous separation and determination of six target compounds (puerarin, daidzin, genistein, daidzein, genistin, and formononetin) inPuerariae LobataeRadix was established by cloud point extraction (CPE) and concentration combined with high performance liquid chromatography (HPLC). To achieve high extraction yields, an ultrasound-assisted extraction method was developed based on a salt-modified Triton X-100 system. The optimal extraction conditions are: surfactant Triton X-100 concentration 0.07 g/mL, liquid-solid ratio 80:1 (mL/g), NaCl addition amount 0.6 g, equilibrium time 40 min, equilibrium temperature 70 °C. Under the optimal conditions, the total maximum extraction yield of the six target isoflavones reached 8.92 mg/g. Usingl-tyrosine andl-dopa as substrates, the effects of puerarin on the monophenolase and diphenolase activity of tyrosinase activity were investigated by the enzyme kinetics method. The results showed that puerarin inhibited monophenolase activity with an IC50of 0.537 mg/mL and activated diphenolase activity. The inhibition type of puerarin on monophenolase and the activation type of puerarin on diphenolase were analyzed by Lineweaver-Burk plots which show that puerarin showed mixed inhibition on monophenolase and mixed activation on diphenolase. Therefore, puerarin can be used as both a tyrosinase inhibitor and a tyrosinase activator.Keywords:Puerariae LobataeRadix;cloud point extractions;tyrosinase inhibitors;tyrosinase activator;kinetic analysis
研究领域:
药理学
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植物化学
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酶学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
TALANTA
·
2019
·
IF 4.916
Yu-Zhu Ding,Wei-Feng Wang,Tian Chai,Yin Qiang,Yan-Ping Shi,Jun-Li Yang
Tyrosinase is the key enzyme in the treatment of vitiligo. Development of rapid, simple, and visual methods for screening bioactive compounds with tyrosinase activity from natural compounds is interesting for new drug discovery. Herein, a novel visual ratiometric fluorescent assay for screening tyrosinase activators and/or inhibitors based on silicon nanoparticles (Si NPs) was explored. Inspired by the changes in both of the solution color and the fluorescence emission due to the sensing between Si NPs and dopamine (DA), we employed tyramine as the model substrate, which can transfer into DA by tyrosinase. It was found that the tyrosinase-incubated tyramine solution exhibited pale yellow under nature light or yellow fluorescence under UV light in the presence of Si NPs, where the color/fluorescence intensity were directly related to the concentration of tyrosinase. The established method showed good detection selectivity , and the LOD for tyrosinase was 0.14 U mL −1 . Eventually, this assay was successfully applied to screen tyrosinase activators or inhibitors from a natural product-like library, and a tyrosinase activator with EC 50 of 2.62 μM, more potent than the commonly used tyrosinase activator 8-MOP, was discovered.
研究领域:
生物化学
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药学
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纳米技术
·
药物发现
✓ 已验证
产品关联
DOI
PubMed
高影响因子
BIOCHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 4.446
Jiaheng Wang,Nuo Zhang,Yawen Huang,Shunyi Li,Guimin Zhang
p -Coumaric acid (para-hydroxycinnamic acid, p -HCA), as a kind of natural active substance from plant cell walls, is widely used in medicine, food, and cosmetics with its antioxidant, anticancer, and other properties. Biological production of p -HCA can be achieved via one-step deamination of the L -tyrosine by tyrosine ammonia-lyase (TAL). Here, a new highly active TAL ( Fc -TAL) from Flavobacterium columnare was identified via gene mining and heterologous expression . The purified Fc -TAL completely converts 22 mM L -tyrosine to p -HCA under alkaline condition (pH 9.5–10.0) at 55 °C. To increase enzymatic recyclability and reduce the bioproduction cost, Fc -TAL was immobilized on a silica nanospheres through silica-binding peptides (SiBP2) at pH 10. In comparison to free enzyme , the immobilized TAL SiBP2 exhibited higher stability, over 50% activity was retained even after 10 consecutive catalytic cycles. Further experiments revealed that an aliquot of immobilized enzyme (about 200 mg TAL) can transform 20 g L -tyrosine into17.8 g p -HCA with 96% yields and 98% purity through 5 consecutive reaction cycles. Our studies not only provided a strategy for enzyme immobilization in alkaline condition, but also developed a green process for p -coumaric acid biosynthesis with the highest conversion rate and yield reported to date.
研究领域:
生物化学
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生物技术
·
酶学
·
药学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sensors
·
2025
·
IF 9.1
Zuhua Zeng,Ying Tan,Tiantian Luo,Zhengwei Li,Guihao Hu,Yao Liu,Ling He,Haiyu Wang,Lei Zhong,Haiying Wang,Tianwei Liu,Jiang Zhu
Melanoma is one of the most aggressive forms of skin cancer. Accurate and early diagnosis of melanoma is crucial for improving patient outcomes. This study develops two TYR-activatable molecular probes, Mn-TyrEDTA and Al-18F-TyrEDTA, for the selective detection of melanoma in vivo. In vitro studies reveal that Mn-TyrEDTA exhibits TYR activity-dependent relaxivity enhancement, undergoing TYR-mediated oxidative polymerization, resulting in the formation of paramagnetic oligomers. UV–vis analysis supports this mechanism, showing time- and TYR concentration-dependent increases in broad band absorbance in the UV–vis region, specifically around 475 nm, due to the formation of o-quinone intermediates and melanin-like oligomers. HPLC analysis further confirmed the presence of polar oligomeric products in Mn-TyrEDTA solutions incubated with TYR/O2. MRI studies demonstrate Mn-TyrEDTA’s selective retention and signal enhancement in TYR-expressing melanoma tissues. Furthermore, PET imaging with Al-18F-TyrEDTA conducted using a dual-xenograft mouse model reveals significantly higher uptake and retention of Al-18F-TyrEDTA in TYR-expressing melanoma compared to TYR-negative tumors. This selective retention could be attributed to a TYR-mediated proximity labeling mechanism, where highly reactive quinones form covalent bonds with nearby tumor proteins. In summary, our findings establish Mn-TyrEDTA and Al-18F-TyrEDTA as promising TYR-activatable imaging probes, offering a novel strategy for the early diagnosis and prognosis of melanoma.
研究领域:
医学影像学
·
肿瘤学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POLYMER JOURNAL
·
2016
·Vol. 48
·期 7
·807-812
·
IF 1.629
Yang Yong,Sun Chen,Zhou Yuming,Wang Tianhe,Zhang Yiwei
Optically active polyurethane (OPU) and racemic polyurethane (RPU) derived from chiral and racemic tyrosine were synthesized using a hydrogen transfer addition polymerization procedure. The structural and optical properties of the polyurethanes were systematically investigated using Fourier transform infrared spectroscopy, 1 H NMR, gel permeation chromatography (GPC), UV-vis spectroscopy, circular dichroism spectroscopy, thermogravimetric analysis (TGA) and X-ray diffraction techniques. In contrast to RPU, OPU possesses a single-handed helical conformation and optical activity owing to the induced asymmetric force field in the chiral monomer. This regular secondary structure facilitates the formation of numerous interchain hydrogen bonds, which increases the crystallinity and thermal stability of OPU. The high-temperature infrared spectroscopy results indicate that the hydrogen bonding collapses before thermal decomposition. In contrast to the intense infrared emissivity property of random coiled RPU, both helical stereostructures and hydrogen bonding contribute to decreasing this emissivity for OPU.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
PROCESS BIOCHEMISTRY
·
2019
·
IF 2.883
Yu-Xia Wang,Wei-Chao Su,Qin Wang,Yu-Feng Lin,Yuan Zhou,Long-Fang Lin,Su Ren,Yan-Ting Li,Qing-Xi Chen,Yan Shi
In this study, the antityrosinase and antioxidant activities of four guanidine compounds (GCs), including guanylthiourea (GT), guanidine thiocyanate (GTC), phenylguanidine (PG), and phenethyldiguanide (PTDG), were investigated. The results showed that the GCs reduced the monophenolase and diphenolase activities of tyrosinase. The IC 50 values of GT, GTC, PG, and PTDG were 0.27, 3.53, 6.68, and 5.18 mM for monophenolase and 0.23, 3.24, 3.97 and 2.50 mM for diphenolase, respectively. The inhibition of diphenolase activity was reversible for the four GCs. The inhibition types of GT and PTDG were competitive, while those of GTC and PG were mixed. FRAP, ABTS, DPPH, and DNA damage protection assays revealed that only GT possessed significant antioxidant activity. Furthermore, GT was found to decrease the melanin content and expression of TYR, MITF and DCT in both B16F10 cells and zebrafish. Overall, our results indicated that GT can inhibit tyrosinase activity in vitro , which suggests that these GCs are potential candidates for novel small-molecule tyrosinase inhibitors and that GT could have broader application prospects.
研究领域:
药理学
·
生物化学
·
细胞生物学
·
分子生物学
✓ 已验证
产品关联
DOI
高影响因子
TALANTA
·
2016
·
IF 4.035
Yun Guan,Lanjunzi Liu,Chao Chen,Xiuzhi Kang,Qingji Xie
The facile preparation of poly( l -DOPA)-tyrosinase (PD M -Tyr) composite and its application both in substrate (phenol) and inhibitor (atrazine) sensing is reported here for the first time. Effective immobilization of enzyme is realized via in-situ entrapping Tyr in poly( l -DOPA) (PD M ), which is formed by Tyr catalytic polymerization of l -DOPA. The Tyr modified electrode is simply prepared by dipping the PD M -Tyr composite on an Au electrode and then covered by Nafion. The thus-prepared Tyr-immobilized electrode exhibits excellent performance superior to most Tyr-based electrochemical biosensors, the sensitivity to phenol is as high as 5122 μA mM −1 in the linear range of 10 nM~1.25 μM, the apparent Michaelis-Menten constant ( K M app ) determined as low as 3.13 μM indicates strong substrate binding and high catalytic activity of the immobilized Tyr. The biosensor also works well in atrazine biosensing, with a linear detection range of 50 ppb~30 ppm and a low detection limit of 10 ppb obtained. In addition, the biosensor shows excellent stability, precision, high sensitivity and fabrication simplicity.
研究领域:
生物化学
·
环境科学
·
分析化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）