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Sonkar KS, Pachauri M, Kumar A, Choudhary H, Jagannadham MV. Conformational stability of peroxidase from the latex of Artocarpus lakoocha: influence of pH, chaotropes, and temperature. FRONTIERS IN PLANT SCIENCE 2024; 15:1341454. [PMID: 38476686 PMCID: PMC10929713 DOI: 10.3389/fpls.2024.1341454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 02/02/2024] [Indexed: 03/14/2024]
Abstract
The latex of the medicinal plant Artocarpus lakoocha (A. lakoocha), which has been shown to have potential anti-inflammatory and wound-healing capabilities, contains a novel heme-peroxidase. This protein was subjected to activity assays, fluorescence spectroscopy, and far-UV circular dichroism to investigate its structure, dynamics, and stability. The results demonstrated the presence of three folding states: the native state (N) at neutral pH, intermediate states including molten globule (MG) at pH 2 and acid-unfolded (UA) at pH 1.5 or lower, and acid-refolded (A) at pH 0.5, along with alkaline denatured (UB) at pH 8-12 and the third denatured state (D) at GuHCl concentrations exceeding 5 M. Absorbance studies indicated the presence of loosely associated form of heme in the pH range of 1-2. The protein showed stability and structural integrity across a wide pH range (3-10), temperature (70°C), and high concentrations of GuHCl (5 M) and urea (8 M). This study is the first to report multiple 'partially folded intermediate states' of A. lakoocha peroxidase, with varying amounts of secondary structure, stability, and compactness. These results demonstrate the high stability of A. lakoocha peroxidase and its potential for biotechnological and industrial applications, making it a valuable model system for further studies on its structure-function relationship.
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Affiliation(s)
- Kirti Shila Sonkar
- Molecular Biology Unit, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | | | - Amit Kumar
- Department of Biochemistry, University of Delhi, New Delhi, India
| | - Himanshi Choudhary
- Molecular Pathology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
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Yu JJ, Zhang ZY, Lin XN, Ji YQ, Zhang RR, Ji H, Chen Y. Changes in the structure and hydration properties of high-temperature peanut protein induced by cold plasma oxidation. Int J Biol Macromol 2023; 253:127500. [PMID: 37858644 DOI: 10.1016/j.ijbiomac.2023.127500] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/09/2023] [Accepted: 10/16/2023] [Indexed: 10/21/2023]
Abstract
To improve the hydration properties of high-temperature pressed peanut protein isolate (HPPI), we investigated the effect of cold plasma (CP) oxidation on functional and structural properties. Compared to HPPI, the hydrated molecules number and the surface contact angle were significantly decreased at 70 W, from 77.2 × 109 to 17.7 × 109 and from 85.74° to 57.81°, respectively. The reduction of the sulfhydryl content and the increase of the disulfide bond and di-tyrosine content indicated that the structural transformation was affected by the oxidation effect. In terms of structural changes, a stretched tertiary structure, ordered secondary structure, and rough apparent structure were observed after CP treatment. Additionally, the enhancement of surface free energy and group content such as -COOH, -CO and -OH on the surface of HPPI contributed to the formation of hydrated crystal structures. In general, the oxidation effect of CP effectively improved the hydration properties of HPPI and broaden its application field.
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Affiliation(s)
- Jiao-Jiao Yu
- College of Life Science, Linyi University, Linyi 276005, China.
| | - Zhi-Yao Zhang
- College of Life Science, Linyi University, Linyi 276005, China
| | - Xiang-Na Lin
- College of Life Science, Linyi University, Linyi 276005, China
| | - Yan-Qing Ji
- College of Life Science, Linyi University, Linyi 276005, China
| | - Ran-Ran Zhang
- College of Life Science, Linyi University, Linyi 276005, China
| | - Hui Ji
- College of Life Science, Linyi University, Linyi 276005, China.
| | - Ye Chen
- College of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin 300457, China.
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Yao Y, Zhang B, Pang H, Wang Y, Fu H, Chen X, Wang Y. The effect of radio frequency heating on the inactivation and structure of horseradish peroxidase. Food Chem 2023; 398:133875. [PMID: 35964573 DOI: 10.1016/j.foodchem.2022.133875] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 07/09/2022] [Accepted: 08/05/2022] [Indexed: 10/15/2022]
Abstract
The effects of radio frequency (RF) heating on horseradish peroxidase (HRP) activity and its structure were investigated in this paper. The HRP was heated to 50 °C, 70 °C and 90 °C at different electrode gaps (100, 110 and 120 mm). The relative enzyme activity was 105.33 %-113.73 % at 50 °C, 91.11 %-93.05 % at 70 °C and 47.05 %-68.17 % at 90 °C. Ultraviolet-visible, circular dichroism and fluorescence spectra were used to monitor the variation in secondary and tertiary structure. The results showed that RF heating at the electrode gaps of 120 mm contributed to more severe enzyme inactivation and conformational destruction, which can be explained by the changes in Soret band, secondary structure content and tryptophan fluorescence intensity. This study revealed that enzyme inactivation by RF heating was associated with loss of helical structure, unfolding of enzyme protein and ejection of heme group.
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Affiliation(s)
- Yishun Yao
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China
| | - Bo Zhang
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China
| | - Huiyun Pang
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China
| | - Yequn Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China
| | - Hongfei Fu
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China
| | - Xiangwei Chen
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China
| | - Yunyang Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China.
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Yu J, Jiang P, Li S, Chen Y. Mechanism of improving interfacial hydration characteristic of high‐denatured peanut protein induced by cold plasma. J FOOD PROCESS ENG 2021. [DOI: 10.1111/jfpe.13926] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jiao‐jiao Yu
- College of Food Science and Engineering Tianjin University of Science & Technology Tianjin China
| | - Pei‐yun Jiang
- College of Food Science and Engineering Tianjin University of Science & Technology Tianjin China
| | - Shu‐hong Li
- College of Food Science and Engineering Tianjin University of Science & Technology Tianjin China
| | - Ye Chen
- College of Food Science and Engineering Tianjin University of Science & Technology Tianjin China
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Mukherjee M, Purkayastha P. The exposed amino acids on protein skeleton control protein adsorption on surface-engineered silver nanoparticles. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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6
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Banerjee S. Effect of Glyoxal Modification on a Critical Arginine Residue (Arg-31α) of Hemoglobin: Physiological Implications of Advanced Glycated end Product an in vitro Study. Protein Pept Lett 2019; 27:770-781. [PMID: 31774041 DOI: 10.2174/0929866526666191125101122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 10/31/2019] [Accepted: 10/31/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Non-enzymatic protein glycation is involved in structure and stability changes that impair protein functionality, resulting in several human diseases, such as diabetes and amyloidotic neuropathies (Alzheimer's disease, Parkinson's disease and Andrade's syndrome). Glyoxal, an endogenous reactive oxoaldehyde, increases in diabetes and reacts with several proteins to form advanced glycation end products through Maillard-like reaction. OBJECTIVE Human hemoglobin, the most abundant protein in blood cells is subjected to nonenzymatic modification by reactive oxoaldehydes in diabetic condition. In the present study, the effect of a low concentration of glyoxal (5 μM) on hemoglobin (10 μM) has been investigated following a period of 30 days incubation in vitro. METHODS Different techniques, mostly biophysical and spectroscopic (e.g. circular dichroism, differential scanning calorimetric study, dynamic light scattering, mass spectrometry, etc.) were used to study glyoxal-induced changes of hemoglobin. RESULTS Glyoxal-treated hemoglobin exhibits decreased absorbance around 280 nm, decreased fluorescence and reduced surface hydrophobicity compared to normal hemoglobin. Glyoxal treatment enhances the stability of hemoglobin and lowers its susceptibility to thermal aggregation compared to control hemoglobin as seen by different studies. Finally, peptide mass fingerprinting study showed glyoxal to modify an arginine residue of α-chain of hemoglobin (Arg-31α) to hydroimidazolone. CONCLUSION Increased level of glyoxal in diabetes mellitus as well as its high reactivity may cause modifications of the heme protein. Thus, considering the significance of glyoxal-induced protein modification under physiological conditions, the observation appears clinically relevant in terms of understanding hydroimidazolone-mediated protein modification under in vivo conditions.
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Affiliation(s)
- Sauradipta Banerjee
- Department of Biophysics, Molecular Biology & Bioinformatics, University of Calcutta, Kolkata 700009, India
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7
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Kinetic and thermodynamic characterization of a novel Aspergillus aculeatus URM4953 polygalacturonase. Comparison of free and calcium alginate-immobilized enzyme. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.07.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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8
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Biophysical, photochemical and biochemical characterization of a protease from Aspergillus tamarii URM4634. Int J Biol Macromol 2018; 118:1655-1666. [DOI: 10.1016/j.ijbiomac.2018.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/01/2018] [Accepted: 07/03/2018] [Indexed: 01/09/2023]
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9
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Inactivation Kinetics of Pectin Methylesterase, Polyphenol Oxidase, and Peroxidase in Cloudy Apple Juice under Microwave and Conventional Heating to Evaluate Non-Thermal Microwave Effects. FOOD BIOPROCESS TECH 2018. [DOI: 10.1007/s11947-018-2109-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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10
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Kheirabadi EK, Razavi SH, Khodaiyan F, Golmakani MT. Optimizing the Extraction of Acid-soluble Collagen Inside the Eggshell Membrane. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2018. [DOI: 10.3136/fstr.24.385] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Elahe Kazemi Kheirabadi
- Department of Food Science, Engineering and Technology, Faculty of Agricultural Engineering and Technology, University of Tehran
| | - Seyed hadi Razavi
- Department of Food Science, Engineering and Technology, Faculty of Agricultural Engineering and Technology, University of Tehran
| | - Faramarz Khodaiyan
- Department of Food Science, Engineering and Technology, Faculty of Agricultural Engineering and Technology, University of Tehran
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Pellicer JA, Gómez-López VM. Pulsed light inactivation of horseradish peroxidase and associated structural changes. Food Chem 2017; 237:632-637. [DOI: 10.1016/j.foodchem.2017.05.151] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 11/29/2022]
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12
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Moosavi-Movahedi Z, Kalejahi ES, Nourisefat M, Maghami P, Poursasan N, Moosavi-Movahedi AA. Mixed SDS-Hemin-Imidazole at low ionic strength being efficient peroxidase-like as a nanozyme. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.02.086] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Cha HJ, Jang DS, Jin KS, Choi KY. Structural analyses combined with small-angle X-ray scattering reveals that the retention of heme is critical for maintaining the structure of horseradish peroxidase under denaturing conditions. Amino Acids 2017; 49:715-723. [PMID: 28144743 DOI: 10.1007/s00726-016-2372-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/23/2016] [Indexed: 11/29/2022]
Abstract
We analyzed the structure of horseradish peroxidase (HRP) under denaturing conditions of 9 M urea or 6 M guanidine hydrochloride (GdnHCl). Far-UV circular dichroism (CD) spectra indicated the existence of native-like secondary structure of holo-HRP in 9 M urea. In addition, slight changes in near-UV and Soret region CD spectra of holo-HRP in 9 M urea suggest that the tertiary structure of holo-HRP and the binding of heme remain partially intact in this condition. A transition in the thermal unfolding transition curve of holo-HRP in 9 M urea indicated the existence of a considerable amount of secondary structure. However, no secondary structure, tertiary structure, or interaction between heme and HRP were observed in holo-HRP in 6 M GdnHCl. Small-angle X-ray scattering indicated that although distal and proximal domains of holo-HRP in 9 M urea might be partially unfolded, the central region that contains the heme might maintain its tertiary structure. Our results suggest that retention of the heme is essential for maintenance of the structure of HRP under highly denaturing conditions.
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Affiliation(s)
- Hyung Jin Cha
- Pohang Accelerator Laboratory, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - Do Soo Jang
- Department of Life Sciences, POSTECH, Pohang, Korea.,Huons Co., Ltd., Seongnam, Korea
| | - Kyeong Sik Jin
- Pohang Accelerator Laboratory, Pohang University of Science and Technology (POSTECH), Pohang, Korea.
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14
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Thuanthong M, Sirinupong N, Youravong W. Triple helical structure of acid-soluble collagen derived from Nile tilapia skin as affected by extraction temperature. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2016; 96:3795-3800. [PMID: 26676993 DOI: 10.1002/jsfa.7572] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/21/2015] [Accepted: 11/30/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND Fish skin has become a new source of collagen. It is usually extracted at low temperature. Increasing the extraction temperature can increase the collagen yield. However, high temperature might cause degradation of the triple helical structure of collagen, which is related to its functional biomaterial. This work thus aimed to investigate the effect of extraction temperature on the extraction efficiency and characteristics of acid-soluble collagen (ASC), particularly its triple helical structure. RESULTS ASC was extracted at 5 ± 1, 15 ± 1 and 25 ± 1 °C for 0-24 h with 0.3 or 0.5 mol L(-1) acetic acid. The results showed that extraction with 0.5 mol L(-1) acetic acid gave a higher extraction efficiency than that in 0.3 mol L(-1) acetic acid (P < 0.5). Extraction at 25 ± 1 °C for 5 h with 0.5 mol L(-1) acetic acid gave a higher extraction efficiency (73.73 ± 1.28%), which is higher than that of 5 ± 1 °C by about 1.7-fold. All ASC obtained were identified as type I collagen and showed similar physicochemical properties. CONCLUSION The results showed that extraction temperature strongly affected extraction efficiency. Extraction at 25 °C did not affect the triple helical structure, which was confirmed by the results of Fourier transform infrared, circular dichroism spectrum and collagen self-assembly. © 2015 Society of Chemical Industry.
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Affiliation(s)
- Mantaka Thuanthong
- Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Songkhla, Thailand
- Membrane Science and Technology Research Center, Prince of Songkla University, Songkla University, Songkhla, Thailand
| | - Nualpun Sirinupong
- Nutraceutical and Functional Foods Research and Development Center, Prince of Songkla University, Songkhla, Thailand
| | - Wirote Youravong
- Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Songkhla, Thailand
- Membrane Science and Technology Research Center, Prince of Songkla University, Songkla University, Songkhla, Thailand
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15
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Sánchez-Leija RJ, Torres-Lubián JR, Reséndiz-Rubio A, Luna-Bárcenas G, Mota-Morales JD. Enzyme-mediated free radical polymerization of acrylamide in deep eutectic solvents. RSC Adv 2016. [DOI: 10.1039/c5ra27468k] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The enzyme-mediated free radical polymerization of acrylamide was performed in nearly non-aqueous DES, which allowed the exploration of higher and lower temperatures that in aqueous media.
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Affiliation(s)
- R. J. Sánchez-Leija
- Centro de Investigación y de Estudios Avanzados Unidad Querétaro
- Querétaro 76230
- Mexico
| | | | - A. Reséndiz-Rubio
- Centro de Investigación y de Estudios Avanzados Unidad Querétaro
- Querétaro 76230
- Mexico
| | - G. Luna-Bárcenas
- Centro de Investigación y de Estudios Avanzados Unidad Querétaro
- Querétaro 76230
- Mexico
| | - J. D. Mota-Morales
- CONACYT Research Fellow at Centro de Nanociencias y Nanotecnología-UNAM
- Ensenada
- Mexico
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Bußler S, Steins V, Ehlbeck J, Schlüter O. Impact of thermal treatment versus cold atmospheric plasma processing on the techno-functional protein properties from Pisum sativum ‘Salamanca’. J FOOD ENG 2015. [DOI: 10.1016/j.jfoodeng.2015.05.036] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Jain R, Kumar R, Kumar S, Chhabra R, Agarwal MC, Kumar R. Analysis of the pH-dependent stability and millisecond folding kinetics of horse cytochrome c. Arch Biochem Biophys 2015; 585:52-63. [DOI: 10.1016/j.abb.2015.09.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Revised: 09/10/2015] [Accepted: 09/14/2015] [Indexed: 11/26/2022]
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18
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Stability and structural changes of horseradish peroxidase: Microwave versus conventional heating treatment. Enzyme Microb Technol 2015; 69:10-8. [DOI: 10.1016/j.enzmictec.2014.11.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 11/10/2014] [Accepted: 11/14/2014] [Indexed: 11/22/2022]
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19
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Shank LP, Kijjanapanich P, Phutrakul S, Fongbua N. Characterization of Partially Purified Peroxidase from Fingerroot (Boesenbergia Rotunda (L.) Mansf.). ACTA ACUST UNITED AC 2015. [DOI: 10.12720/jomb.4.3.170-177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kalaiarasan E, Palvannan T. Removal of phenols from acidic environment by horseradish peroxidase (HRP): Aqueous thermostabilization of HRP by polysaccharide additives. J Taiwan Inst Chem Eng 2014. [DOI: 10.1016/j.jtice.2013.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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21
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Modification of Lysine Residues of Horseradish Peroxidase and Its Effect on Stability and Structure of the Enzyme. Appl Biochem Biotechnol 2014; 172:3558-69. [DOI: 10.1007/s12010-014-0756-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 01/21/2014] [Indexed: 10/25/2022]
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22
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Surowsky B, Fischer A, Schlueter O, Knorr D. Cold plasma effects on enzyme activity in a model food system. INNOV FOOD SCI EMERG 2013. [DOI: 10.1016/j.ifset.2013.04.002] [Citation(s) in RCA: 195] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Karim Z, Adnan R, Ansari MS. Low concentration of silver nanoparticles not only enhances the activity of horseradish peroxidase but alter the structure also. PLoS One 2012; 7:e41422. [PMID: 22848490 PMCID: PMC3407207 DOI: 10.1371/journal.pone.0041422] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 06/21/2012] [Indexed: 02/01/2023] Open
Abstract
Chemical synthesis of Ag-NPs was carried out using reduction method. The reduction mechanistic approach of silver ions was found to be a basic clue for the formation of the Ag-NPs. The nanoparticles were characterized by UV-vis, FT-IR and TEM analysis. We had designed some experiments in support of our hypothesis, "low concentrations of novel nanoparticles (silver and gold) increases the activity of plant peroxidases and alter their structure also", we had used Ag-NPs and HRP as models. The immobilization/interaction experiment had demonstrated the specific concentration range of the Ag-NPs and within this range, an increase in HRP activity was reported. At 0.08 mM concentration of Ag-NPs, 50% increase in the activity yield was found. The U.V-vis spectra had demonstrated the increase in the absorbance of HRP within the reported concentration range (0.06-0.12 mM). Above and below this concentration range there was a decrease in the activity of HRP. The results that we had found from the fluorescence spectra were also in favor of our hypothesis. There was a maximum increase in ellipticity and α-helix contents in the presence of 0.08 mM concentration of Ag-NPs, demonstrated by circular dichroism (CD) spectra. Finally, incubation of a plant peroxidase, HRP with Ag-NPs, within the reported concentration range not only enhances the activity but also alter the structure.
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Affiliation(s)
- Zoheb Karim
- School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia
| | - Rohana Adnan
- School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia
| | - Mohd Saquib Ansari
- School of Biomedical Sciences, Shaheed Rajguru College of Applied Sciences for Woman Delhi University, Delhi, India
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Guo S, Wang L, Lu A, Lu T, Ding X, Huang X. Inhibition mechanism of lanthanum ion on the activity of horseradish peroxidase in vitro. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 75:936-940. [PMID: 20005154 DOI: 10.1016/j.saa.2009.11.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 11/13/2009] [Indexed: 05/28/2023]
Abstract
In order to understand the inhibition mechanism of lanthanum ion (La(3+)) on the activity of horseradish peroxidase (HRP), the effects of La(3+) on the activity, electron transfer and conformation of HRP in vitro were investigated by using cyclic voltammetry (CV), atomic force microscopy (AFM), circular dichroism (CD), high performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF/MS) and inductively coupled plasma mass spectrometry (ICP-MS). It was found that La(3+) can combine with the amide groups of the polypeptide chain in HRP molecule, forming the complex of La(3+) and HRP (La-HRP). The formation of the La-HRP complex causes the destruction of the native structure of HRP molecule, leading to the decrease in the non-planarity of the porphyrin ring in the heme group of HRP molecule, and then in the exposure extent of active center, Fe(III) of the porphyrin ring of HRP molecule. Thus, the direct electrochemical and catalytic activities of HRP are decreased. It is a possible inhibition mechanism of La(3+) on the activity of peroxidase.
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Affiliation(s)
- Shaofen Guo
- Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environment Science, Nanjing Normal University, Nanjing 210097, PR China
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Wang L, Lu A, Lu T, Ding X, Huang X. Interaction between lanthanum ion and horseradish peroxidase in vitro. Biochimie 2009; 92:41-50. [PMID: 19822184 DOI: 10.1016/j.biochi.2009.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 09/11/2009] [Indexed: 11/28/2022]
Abstract
The interaction between lanthanum ion (La(3+)) and horseradish peroxidase (HRP) in vitro was investigated using a combination of biophysical and biochemical methods. When the molar ratio of La(3+) and HRP is low, it was found that the interaction between La(3+) and HRP mainly depends on the electrostatic attraction, van der waals force and hydrogen bond etc. Thus, the interaction is weak and the La-HRP complex cannot be formed in vitro. As expected, the interaction can change the conformation of HRP molecule, leading to the increase in the non-planarity of the porphyrin ring in the heme group of HRP molecule, and then in the exposure degree of the active center, Fe(III) of the porphyrin ring of HRP molecule. Therefore, the catalytic activity of HRP for the H(2)O(2) reduction is improved. When the molar ratio of La(3+) and HRP is high, La(3+) can strongly coordinate with O and/or N in the amide group of the polypeptide chain of HRP molecule, forming the La-HRP complex. The formation of the La-HRP complex causes the change in the conformation of HRP molecule, leading to the decrease in the non-planarity of the porphyrin ring in the heme group of HRP molecule, and then in the exposure degree of the active center, Fe(III) of the porphyrin ring of HRP molecule. Thus, the catalytic activity of HRP for the H(2)O(2) reduction is decreased comparing with that of HRP in the absence of La(3+). The results can provide some references for understanding the interaction mechanism between trace elements ions and peroxidase in living organisms.
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WANG LINGZHAO, YANG BAO, DU XIUQIAO. EXTRACTION OF ACID-SOLUBLE COLLAGEN FROM GRASS CARP (CTENOPHARYNGODON IDELLA) SKIN. J FOOD PROCESS ENG 2009. [DOI: 10.1111/j.1745-4530.2008.00242.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Song HY, Liu JZ, Weng LP, Ji LN. Activity, stability, and unfolding of reconstituted horseradish peroxidase with modified heme. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.molcatb.2008.06.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Liao X, Zhang Y, Bei J, Hu X, Wu J. Alterations of molecular properties of lipoxygenase induced by dense phase carbon dioxide. INNOV FOOD SCI EMERG 2009. [DOI: 10.1016/j.ifset.2008.06.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Ye Y, Wang L, Huang X, Lu T, Ding X, Zhou Q, Guo S. Subcellular location of horseradish peroxidase in horseradish leaves treated with La(III), Ce(III) and Tb(III). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2008; 71:677-684. [PMID: 18261795 DOI: 10.1016/j.ecoenv.2007.11.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 11/13/2007] [Accepted: 11/29/2007] [Indexed: 05/25/2023]
Abstract
The agricultural application of rare-earth elements (REEs) would promote REEs inevitably to enter in the environment and then to threaten the environmental safety and human health. Therefore, the distribution of the REEs ion, (141)Ce(III) and effects of La(III), Ce(III) and Tb(III) on the distribution of horseradish peroxidase (HRP) in horseradish mesophyll cells were investigated with electron microscopic radioautography and transmission electron microscopic cytochemistry. It was found for the first time that REEs ions can enter into the mesophyll cells, deposit in both extra and intra-cellular. Compared to the normal condition, after the horseradish leaves treated with La(III) or Tb(III), HRP located on the tonoplast is decreased and HRP is mainly located on the cell wall, while HRP is mainly located on the plasma membrane after the horseradish leaves were treated with Ce(III). This also indicated that REEs ions may regulate the plant growth through changing the distribution of enzymes.
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Affiliation(s)
- Yaxin Ye
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
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Guo S, Zhou Q, Lu T, Ding X, Huang X. Inhibition Mechanism of TbIIIon Horseradish Peroxidase Activity. Chem Biodivers 2008; 5:2050-2059. [DOI: 10.1002/cbdv.200890187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Wang L, Yang B, Du X, Yang Y, Liu J. Optimization of conditions for extraction of acid-soluble collagen from grass carp (Ctenopharyngodon idella) by response surface methodology. INNOV FOOD SCI EMERG 2008. [DOI: 10.1016/j.ifset.2008.03.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Guo S, Cao R, Lu A, Zhou Q, Lu T, Ding X, Li C, Huang X. One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III). J Biol Inorg Chem 2008; 13:587-97. [PMID: 18274791 DOI: 10.1007/s00775-008-0347-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2007] [Accepted: 01/27/2008] [Indexed: 11/25/2022]
Abstract
One of the possible mechanisms for the inhibition effect of Tb(III) on peroxidase activity in horseradish (Armoracia rusticana) treated with Tb(III) was investigated using some biophysical and biochemical methods. Firstly, it was found that a large amount of Tb(III) can be distributed on the cell wall, that some Tb(III) can enter into the horseradish cell, indicating that peroxidase was mainly distributed on cell wall, and thus that Tb(III) would interact with horseradish peroxidase (HRP) in the plant. In addition, peroxidase bioactivity was decreased in the presence of Tb(III). Secondly, a new peroxidase-containing Tb(III) complex (Tb-HRP) was obtained from horseradish after treatment with Tb(III); the molecular mass of Tb-HRP is near 44 kDa and the pI is about 8.80. Thirdly, the electrocatalytic activity of Tb-HRP is much lower than that of HRP obtained from horseradish without treatment with Tb(III). The decrease in the activity of Tb-HRP is due to the destruction (unfolding) of the conformation in Tb-HRP. The planarity of the heme active center in the Tb-HRP molecule was increased and the extent of exposure of Fe(III) in heme was decreased, leading to inhibition of the electron transfer. The microstructure change in Tb-HRP might be the result of the inhibition effect of Tb(III) on peroxidase activity in horseradish.
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Affiliation(s)
- Shaofen Guo
- Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Environmental Science, Nanjing Normal University, Nanjing 210097, People's Republic of China
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Guo S, Zhou Q, Lu T, Ding X, Huang X. Spectroscopic studies of interactions involving horseradish peroxidase and Tb3+. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 70:818-823. [PMID: 18024195 DOI: 10.1016/j.saa.2007.09.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2007] [Revised: 09/18/2007] [Accepted: 09/20/2007] [Indexed: 05/25/2023]
Abstract
The spectroscopic properties of interactions involving horseradish peroxidase (HRP) and Tb3+ in the simulated physiological solution was investigated with some electrochemical and spectroscopic methods, such as cyclic voltammetry (CV), circular dichroism (CD), X-ray photoelectron spectroscopy (XPS) and synchronous fluorescence (SF). It was found that Tb3+ can coordinate with oxygen atoms in carbonyl groups in the peptide chain of HRP, form the complex of Tb3+ and HRP (Tb-HRP), and then lead to the conformation change of HRP. The increase in the random coil content of HRP can disturb the microstructure of the heme active center of HRP, in which the planarity of the porphyrin cycle in the heme group is increased and then the exposure extent of the electrochemical active center is decreased. Thus Tb3+ can inhibit the electrochemical reaction of HRP and its electrocatalytic activity for the reduction of H2O2 at the Au/Cys/GC electrode. The changes in the microstructure of HRP obstructed the electron transfer of Fe(III) in the porphyrin cycle of the heme group, thus HRP catalytic activity is inhibited. The inhibition effect of Tb3+ on HRP catalytic activity is increased with the increasing of Tb3+ concentration. This study would provide some references for better understanding the rare earth elements and heavy metals on peroxidase toxicity in living organisms.
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Affiliation(s)
- Shaofen Guo
- The Key Laboratory of Industry Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
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Feng JY, Liu JZ, Ji LN. Thermostability, solvent tolerance, catalytic activity and conformation of cofactor modified horseradish peroxidase. Biochimie 2008; 90:1337-46. [PMID: 18439429 DOI: 10.1016/j.biochi.2008.03.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Accepted: 03/26/2008] [Indexed: 10/22/2022]
Abstract
Artificial prosthetic groups, HeminD1 and HeminD2, were designed and synthesized, which contain one benzene ring and one carboxylic group or two carboxylic groups at the terminal of each propionate side chain of hemin, respectively. HeminD1 and HeminD2 were reconstituted with apo-HRP successfully to produce the two novel HRPs, rHRP1 and rHRP2, respectively. The thermal and solvent tolerances of native and reconstituted HRPs were compared. The cofactor modification increased the thermostability both in aqueous buffer and some organic solvents, and also enhanced the tolerance of some organic solvents. To determine the conformation stability, the unfolding of native and reconstituted HRPs by heat was investigated. Tm was increased from 70.0 degrees C of nHRP to 75.4 degrees C of rHRP1 and 76.5 degrees C of rHRP2 after cofactor modification. Kinetic studies indicated that the cofactor modification increased the substrate affinity and catalytic efficiency both in aqueous buffer and some organic solvents. The catalytic efficiency for phenol oxidation was increased by approximately 55% for rHRP1 in aqueous buffer, and it was also increased by approximately 70% for rHRP1 in 10% ACN. Spectroscopic studies proved that the cofactor modification changed the microenvironment of both heme and tryptophan, increased alpha-helix content, and increased the tertiary structure around the aromatic residue in HRP. The improvements of catalytic properties are related to these changes of the conformation. The introduction of the hydrophobic domain as well as the retention of the moderate carboxylic group in active site is an efficient method to improve the thermodynamic and catalytic efficiency of HRP.
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Affiliation(s)
- Jiu-Ying Feng
- Key Laboratory of Gene Engineering of Ministry of Education and Biotechnology Research Center, State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou 510275, PR China
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Liu JZ, Wang M. Improvement of activity and stability of chloroperoxidase by chemical modification. BMC Biotechnol 2007; 7:23. [PMID: 17511866 PMCID: PMC1891289 DOI: 10.1186/1472-6750-7-23] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Accepted: 05/18/2007] [Indexed: 11/10/2022] Open
Abstract
Background Enzymes show relative instability in solvents or at elevated temperature and lower activity in organic solvent than in water. These limit the industrial applications of enzymes. Results In order to improve the activity and stability of chloroperoxidase, chloroperoxidase was modified by citraconic anhydride, maleic anhydride or phthalic anhydride. The catalytic activities, thermostabilities and organic solvent tolerances of native and modified enzymes were compared. In aqueous buffer, modified chloroperoxidases showed similar Km values and greater catalytic efficiencies kcat/Km for both sulfoxidation and oxidation of phenol compared to native chloroperoxidase. Of these modified chloroperoxidases, citraconic anhydride-modified chloroperoxidase showed the greatest catalytic efficiency in aqueous buffer. These modifications of chloroperoxidase increased their catalytic efficiencies for sulfoxidation by 12%~26% and catalytic efficiencies for phenol oxidation by 7%~53% in aqueous buffer. However, in organic solvent (DMF), modified chloroperoxidases had lower Km values and higher catalytic efficiencies kcat/Km than native chloroperoxidase. These modifications also improved their thermostabilities by 1~2-fold and solvent tolerances of DMF. CD studies show that these modifications did not change the secondary structure of chloroperoxidase. Fluorescence spectra proved that these modifications changed the environment of tryptophan. Conclusion Chemical modification of epsilon-amino groups of lysine residues of chloroperoxidase using citraconic anhydride, maleic anhydride or phthalic anhydride is a simple and powerful method to enhance catalytic properties of enzyme. The improvements of the activity and stability of chloroperoxidase are related to side chain reorientations of aromatics upon both modifications.
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Affiliation(s)
- Jian-Zhong Liu
- Key Laboratory of Gene Engineering of Ministry of Education and Biotechnology Research Center, State Key Laboratory of Biocontrol, Zhongshan University, Guangzhou 510275, PR China
| | - Min Wang
- Key Laboratory of Gene Engineering of Ministry of Education and Biotechnology Research Center, State Key Laboratory of Biocontrol, Zhongshan University, Guangzhou 510275, PR China
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Carvalho ASL, Ferreira BS, Neves-Petersen MT, Petersen SB, Aires-Barros MR, Melo EP. Thermal denaturation of HRPA2: pH-dependent conformational changes. Enzyme Microb Technol 2007. [DOI: 10.1016/j.enzmictec.2006.05.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zhong K, Wu J, Wang Z, Chen F, Liao X, Hu X, Zhang Z. Inactivation kinetics and secondary structural change of PEF-treated POD and PPO. Food Chem 2007. [DOI: 10.1016/j.foodchem.2005.09.035] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Neves-Petersen MT, Klitgaard S, Carvalho ASL, Petersen SB, Aires de Barros MR, Pinho e Melo E. Photophysics and photochemistry of horseradish peroxidase A2 upon ultraviolet illumination. Biophys J 2006; 92:2016-27. [PMID: 17189303 PMCID: PMC1861803 DOI: 10.1529/biophysj.106.095455] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Detailed analysis of the effects of ultraviolet (UV) and blue light illumination of horseradish peroxidase A2, a heme-containing enzyme that reduces H(2)O(2) to oxidize organic and inorganic compounds, is presented. The effects of increasing illumination time on the protein's enzymatic activity, Reinheitzahl value, fluorescence emission, fluorescence lifetime distribution, fluorescence mean lifetime, and heme absorption are reported. UV illumination leads to an exponential decay of the enzyme activity followed by changes in heme group absorption. Longer UV illumination time leads to lower T(m) values as well as helical content loss. Prolonged UV illumination and heme irradiation at 403 nm has a pronounced effect on the fluorescence quantum yield correlated with changes in the prosthetic group pocket, leading to a pronounced decrease in the heme's Soret absorbance band. Analysis of the picosecond-resolved fluorescence emission of horseradish peroxidase A2 with streak camera shows that UV illumination induces an exponential change in the preexponential factors distribution associated to the protein's fluorescence lifetimes, leading to an exponential increase of the mean fluorescence lifetime. Illumination of aromatic residues and of the heme group leads to changes indicative of heme leaving the molecule and/or that photoinduced chemical changes occur in the heme moiety. Our studies bring new insight into light-induced reactions in proteins. We show how streak camera technology can be of outstanding value to follow such ultrafast processes and how streak camera data can be correlated with protein structural changes.
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Affiliation(s)
- Maria Teresa Neves-Petersen
- Department of Physics and Nanotechnology, NanoBiotechnology Section, UltrafastBioSpectroscopy Group, Aalborg University, Aalborg, Denmark.
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Song HY, Yao JH, Liu JZ, Zhou SJ, Xiong YH, Ji LN. Effects of phthalic anhydride modification on horseradish peroxidase stability and structure. Enzyme Microb Technol 2005. [DOI: 10.1016/j.enzmictec.2004.12.018] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Carvalho ASL, Neves-Petersen MT, Petersen SB, Aires-Barros MR, Pinho e Melo E. Formation of a misfolded conformation during refolding of HRPA1 in the presence of calcium. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1747:99-107. [PMID: 15680244 DOI: 10.1016/j.bbapap.2004.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 10/01/2004] [Accepted: 10/06/2004] [Indexed: 11/22/2022]
Abstract
Horseradish peroxidase A1 can refold to a native-like structure without binding calcium, originating a Ca2+-depleted native state as previously demonstrated. Thermal unfolding studies of horseradish peroxidase anionic 1 (HRPA1) have shown that calcium ions present during refolding lead to the appearance of a misfolded conformational state, which cannot incorporate the heme group. This calcium-induced conformational state, ICa2+, is less stable than the native state and has distinct secondary and tertiary structures as probed by far-UV and visible circular dichroism and tryptophan fluorescence. The fraction of ICa2+ increases exponentially with increasing calcium concentration. The ICa2+ state is formed during refolding after calcium binding to the unfolded state, as reconstitution of HRPA1 from its apoprotein reveals that the affinity of the apoprotein to protoporphyrin IX is higher in the presence of calcium. If calcium is added after refolding only, the majority of HRPA1 molecules retain their native conformation, thus confirming the binding of calcium to the unfolded state.
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Affiliation(s)
- Ana Sofia L Carvalho
- Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais 1049-001, Lisboa, Portugal
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Carvalho ASL, Santos AM, Neves-Petersen MT, Petersen SB, Aires-Barros MR, e Melo EP. Conformational states of HRPA1 induced by thermal unfolding: Effect of low molecular weight solutes. Biopolymers 2004; 75:173-86. [PMID: 15356871 DOI: 10.1002/bip.20100] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Fluorescence, CD, and activity measurements were used to characterize the different conformational states of horseradish peroxidase A1 induced by thermal unfolding. Picosecond time-resolved fluorescence studies showed a three-exponential decay dominated by a picosecond lifetime component resulting from energy transfer from tryptophan to heme. Upon thermal unfolding a decrease in the preexponential factor of the picosecond lifetime and an increase in the quantum yield were observed approaching the characteristics observed for apoHRPA1. The fraction of heme-quenched fluorophore decreased to 0.4 after unfolding as shown by acrylamide quenching. A new unfolding pathway for HRPA1 was proposed and the effect of the low molecular weight solutes trehalose, sorbitol, and melezitose on this pathway was analyzed. Native HRPA1 unfolds with an intermediate between the native and the unfolded conformation. The unfolded conformation can refold to the native state or to a native-like conformation with no calcium ions upon cooling or can give an irreversible denatured state. The refolded conformation with no calcium ions was clearly identified in a second thermal scan in the presence of EDTA and shows secondary and tertiary structures, heme reincorporation in the cavity, and at least 59% of activity. Melezitose stabilized the refolded Ca2+-depleted protein and induced a more complex mechanism for heme disruption. The effect of sorbitol and trehalose were mainly characterized by an increase in the temperature of unfolding.
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Affiliation(s)
- Ana Sofia L Carvalho
- Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais 1049-001, Lisboa, Portugal
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