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Dumitraşcu L, Stănciuc N, Bahrim GE, Ciumac A, Aprodu I. pH and heat-dependent behaviour of glucose oxidase down to single molecule level by combined fluorescence spectroscopy and molecular modelling. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2016; 96:1906-1914. [PMID: 26058827 DOI: 10.1002/jsfa.7296] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/06/2015] [Accepted: 06/01/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND In the food industry, glucose oxidase (GOX) is used to improve the shelf life of food materials. The pH- and heat-induced conformational changes of glucose oxidase from Aspergillus niger were quantified by means of fluorescence spectroscopy and molecular dynamics simulations. RESULTS The phase diagram showed an all-or-none transition process, indicating that pH and temperature largely influence the conformational state of GOX. Shifts in maximum wavelength of Trp, Tyr were registered as the protein encounters a lower pH (pH 4.0), suggesting significant changes of the polarity around the chromophore molecule. Quenching experiments using KI showed higher quenching constants of Trp and flavin adenine dinucleotide upon heating or by changing pH value, and were mainly correlated with the conformational changes upon protein matrix. Finally, valuable insights into the thermal behaviour of GOX were obtained from molecular modelling results. CONCLUSIONS The conformation and structure of GOX protein is dependent upon the pH and heat treatment applied. Molecular dynamics simulation indicated significant changes in the substrate binding region at temperatures over 60 °C that might affect enzyme activity. Moreover, an important alteration of the small pocket hosting the positively charged His(516) residue responsible for oxygen activation appears evident at high temperatures.
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Affiliation(s)
- Loredana Dumitraşcu
- Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domneascã Street 111, 800201, Galati, Romania
| | - Nicoleta Stănciuc
- Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domneascã Street 111, 800201, Galati, Romania
| | - Gabriela Elena Bahrim
- Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domneascã Street 111, 800201, Galati, Romania
| | - Alexandrina Ciumac
- Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domneascã Street 111, 800201, Galati, Romania
| | - Iuliana Aprodu
- Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domneascã Street 111, 800201, Galati, Romania
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52
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Thermally driven interactions between β-lactoglobulin and retinol acetate investigated by fluorescence spectroscopy and molecular modeling methods. ACTA ACUST UNITED AC 2016. [DOI: 10.1007/s13594-015-0277-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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53
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Simion (Ciuciu) AM, Aprodu I, Dumitrașcu L, Bahrim GE, Alexe P, Stănciuc N. Probing thermal stability of the β-lactoglobulin–oleic acid complex by fluorescence spectroscopy and molecular modeling. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.04.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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54
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Influence of substrate nature and β-lactoglobulin on cleanability after soiling by suspension spraying and drying. Chem Eng Sci 2015. [DOI: 10.1016/j.ces.2015.05.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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55
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Stănciuc N, Aprodu I, Ioniță E, Bahrim G, Râpeanu G. Exploring the process-structure-function relationship of horseradish peroxidase through investigation of pH- and heat induced conformational changes. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 147:43-50. [PMID: 25827765 DOI: 10.1016/j.saa.2015.03.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/12/2015] [Accepted: 03/01/2015] [Indexed: 06/04/2023]
Abstract
Given the importance of peroxidase as an indicator for the preservation of vegetables by heat treatment, the present study is focused on enzyme behavior under different pH and temperature conditions, in terms of process-structure-function relationships. Thus, the process-structure-function relationship of peroxidase was investigated by combining fluorescence spectroscopy, in silico prediction methods and inactivation kinetic studies. The fluorescence spectra indicated that at optimum pH value, the Trp(117) residue is not located in the hydrophobic core of the protein. Significant blue- and red-shifts were obtained at different pH values, whereas the heat-treatment did not cause significant changes in Trp and Tyr environment. The ANS and quenching experiments demonstrated a more flexible conformation at lower pH and respectively at higher temperature. On the other hand molecular dynamics simulations at different temperatures highlighted that the secondary structure appeared better preserved against temperature, whereas the tertiary structure around the heme was more affected. Temperature dependent changes in the hydrogen bonding and ion paring involving amino acids from the heme-binding region (His(170) and Asp(247)) might trigger miss-coordination of the heme iron atom by His(170) residue and further enzyme activity loss.
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Affiliation(s)
- Nicoleta Stănciuc
- "Dunărea de Jos" University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania
| | - Iuliana Aprodu
- "Dunărea de Jos" University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania
| | - Elena Ioniță
- "Dunărea de Jos" University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania
| | - Gabriela Bahrim
- "Dunărea de Jos" University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania
| | - Gabriela Râpeanu
- "Dunărea de Jos" University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania.
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56
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Simion Ciuciu AM, Aprodu I, Dumitrașcu L, Bahrim GE, Alexe P, Stănciuc N. Exploring the heat-induced structural changes of β-lactoglobulin -linoleic acid complex by fluorescence spectroscopy and molecular modeling techniques. Journal of Food Science and Technology 2015; 52:8095-103. [PMID: 26604382 DOI: 10.1007/s13197-015-1949-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 03/15/2015] [Accepted: 07/07/2015] [Indexed: 01/03/2023]
Abstract
Linoleic acid (LA) is the precursor of bioactive oxidized linoleic acid metabolites and arachidonic acid, therefore is essential for human growth and plays an important role in good health in general. Because of the low water solubility and sensitivity to oxidation, new ways of LA delivery without compromising the sensory attributes of the enriched products are to be identified. The major whey protein, β-lactoglobulin (β-Lg), is a natural carrier for hydrophobic molecules. The thermal induced changes of the β-Lg-LA complex were investigated in the temperature range from 25 to 85 °C using fluorescence spectroscopy techniques in combination with molecular modeling study and the results were compared with those obtained for β-Lg. Experimental results indicated that, regardless of LA binding, the polypeptide chain rearrangements at temperatures higher than 75 °C lead to higher exposure of hydrophobic residues causing the increase of fluorescence intensity. Phase diagram indicated an all or none transition between two conformations. The LA surface involved in the interaction with β-Lg was about 497 Ǻ(2), indicating a good affinity between those two components even at high temperatures. Results obtained in this study provide important details about heat-induced changes in the conformation of β-Lg-LA complex. The thermal treatment at high temperature does not affect the LA binding and carrier functions of β-Lg.
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Affiliation(s)
- Ana-Maria Simion Ciuciu
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Iuliana Aprodu
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Loredana Dumitrașcu
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Gabriela Elena Bahrim
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Petru Alexe
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Nicoleta Stănciuc
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
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57
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Interaction of β-lactoglobulin with (−)-epigallocatechin-3-gallate under different processing conditions of pH and temperature by the fluorescence quenching method. Eur Food Res Technol 2015. [DOI: 10.1007/s00217-015-2466-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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58
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Dumitrașcu L, Stănciuc N, Aprodu I, Ciuciu AM, Alexe P, Bahrim GE. Monitoring the heat-induced structural changes of alkaline phosphatase by molecular modeling, fluorescence spectroscopy and inactivation kinetics investigations. Journal of Food Science and Technology 2015; 52:6290-300. [PMID: 26396374 DOI: 10.1007/s13197-015-1719-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 12/29/2014] [Accepted: 01/02/2015] [Indexed: 11/25/2022]
Abstract
The heat induced conformational changes of calf alkaline phosphatase (ALP) were analyzed using different methods, based on fluorescence spectroscopy, molecular modeling and inactivation studies. Experimental studies were conducted in buffer solution in the temperature range between 25 and 70 °C. Molecular dynamic (MD) simulation provided details on thermally induced changes in ALP structure, highlighting that heating favored the hydrophobic exposure and important alteration of the catalytic site above 60 °C. Additional information to MD data were obtained by using different fluorescence spectroscopy methods, which revealed a complex mechanism of thermal denaturation. Therefore, the emissive properties indicated an unfolding of ALP at temperatures below 60 °C, whereas at higher temperatures, the polypeptides chains fold leading to a higher exposure of Trp residues. In order to establish a structure-function relationship, the results were correlated with inactivation studies of ALP in buffer at pH 9.0. The inactivation data were fitted using a first-order kinetic model, resulting in an activation energy value of 207.26 ± 21.68 kJ · mol(-1).
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Affiliation(s)
- Loredana Dumitrașcu
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Nicoleta Stănciuc
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Iuliana Aprodu
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Ana-Maria Ciuciu
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Petru Alexe
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
| | - Gabriela Elena Bahrim
- Faculty of Food Science and Engineering, Dunarea de Jos University of Galati, Domneasca Street 111, Building E, Room 304, 800201 Galati, Romania
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59
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60
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Probing of the interaction between β-lactoglobulin and the anticancer drug oxaliplatin. Appl Biochem Biotechnol 2014; 175:974-87. [PMID: 25351630 DOI: 10.1007/s12010-014-1341-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 10/15/2014] [Indexed: 01/26/2023]
Abstract
The potential carrier role of β-lactoglobulin (β-LG) and its interactions with oxaliplatin were studied using various spectroscopic techniques (fluorescence, UV-visible, and circular dichroism (CD)) in an aqueous medium at two temperatures of 25 and 37 °C in combination with a molecular docking study. Fluorescence measurements have shown that the observed quenching is a combination of static and dynamic quenching with a predominant contribution of static mode. The presence of a single binding site located in the internal cavity of the β-barrel of β-LG was confirmed by molecular docking calculations. Thermodynamic data as well as molecular docking indicated that the hydrophobic interactions dominate in the binding site. Results of fluorescence resonance energy transfer (FRET) measurements in combination with docking results imply that resonance energy transfer occurs between β-LG and its ligand oxaliplatin. Additionally, CD results revealed that oxaliplatin binding has no influence on the β-LG structure. The molecular docking results indicate that docking may be an appropriate method for the prediction and confirmation of experimental results. Complementary molecular docking results may be useful for the determination of the binding mechanism of proteins such as β-LG in pharmaceutical and biophysical studies providing new insight in the novel pharmacology and new solutions in the formulation of advanced oral drug delivery systems.
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61
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β-Lactoglobulin–naringenin complexes: Nano-vehicles for the delivery of a hydrophobic nutraceutical. Food Hydrocoll 2014. [DOI: 10.1016/j.foodhyd.2014.02.023] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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62
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Zeiler RN, Bolhuis PG. Exposure of thiol groups in the heat-induced denaturation of β-lactoglobulin. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.926547] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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63
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Ghalandari B, Divsalar A, Saboury AA, Haertlé T, Parivar K, Bazl R, Eslami-Moghadam M, Amanlou M. Spectroscopic and theoretical investigation of oxali-palladium interactions with β-lactoglobulin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 118:1038-1046. [PMID: 24161866 DOI: 10.1016/j.saa.2013.09.126] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 09/19/2013] [Accepted: 09/29/2013] [Indexed: 06/02/2023]
Abstract
The possibility of using a small cheap dairy protein, β-lactoglobulin (β-LG), as a carrier for oxali-palladium for drug delivery was studied. Their binding in an aqueous solution at two temperatures of 25 and 37°C was investigated using spectroscopic techniques in combination with a molecular docking study. Fluorescence intensity changes showed combined static and dynamic quenching during β-LG oxali-palladium binding, with the static mode being predominant in the quenching mechanism. The binding and thermodynamic parameters were determined by analyzing the results of quenching and those of the van't Hoff equation. According to obtained results the binding constants at two temperatures of 25 and 37°C are 3.3×10(9) M(-1) and 18.4×10(6) M(-1) respectively. Fluorescence resonance energy transfer (FRET) showed that the experimental results and the molecular docking results were coherent. An absence change of β-LG secondary structure was confirmed by the CD results. Molecular docking results agreed fully with the experimental results since the fluorescence studies also revealed the presence of two binding sites with a negative value for the Gibbs free energy of binding of oxali-palladium to β-LG. Furthermore, molecular docking and experimental results suggest that the hydrophobic effect plays a critical role in the formation of the oxali-palladium complex with β-LG. This agreement between molecular docking and experimental results implies that docking studies may be a suitable method for predicting and confirming experimental results, as shown in this study. Hence, the combination of molecular docking and spectroscopy methods is an effective innovative approach for binding studies, particularly for pharmacophores.
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Affiliation(s)
- Behafarid Ghalandari
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
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64
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Assessing the heat induced changes in major cow and non-cow whey proteins conformation on kinetic and thermodynamic basis. Small Rumin Res 2013. [DOI: 10.1016/j.smallrumres.2012.12.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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65
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Stănciuc N, Aprodu I, Râpeanu G, van der Plancken I, Bahrim G, Hendrickx M. Analysis of the thermally induced structural changes of bovine lactoferrin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:2234-2243. [PMID: 23410159 DOI: 10.1021/jf305178s] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Bovine lactoferrin (LF) is subjected to thermal processing during isolation for commercial use and while preparing milk products intended for infant nutrition. The present study is focused on the heat-induced structural changes of LF in buffer solution. Fluorescence spectroscopy, molecular modeling, and enzymatic hydrolysis studies were combined to extensively characterize LF thermal behavior. The temperature-induced changes induced on LF conformation were analyzed through intrinsic and ANS fluorescence parameters (intensity, maximum position, and parameter A value), the phase diagram method, and quenching experiments using acrylamide and iodide. A higher exposure of hydrophobic residues was highlighted through the molecular modeling approach, with a decrease in α-helix content from 23.5% to 21.2% when increasing the temperature from 25 °C to 80 °C. The experimental results demonstrate a more flexible conformation of the protein at higher temperature, thus facilitating the enzymatic hydrolysis by thermolysin.
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Affiliation(s)
- Nicoleta Stănciuc
- Faculty of Food Science and Engineering, "Dunarea de Jos" University of Galati , 111 Domneasca Street, 800201, Galati, Romania
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66
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Molecular dynamics simulation of the effect of heat on the conformation of bovine β-lactoglobulin A: A comparison of conventional and accelerated methods. Food Hydrocoll 2013. [DOI: 10.1016/j.foodhyd.2012.07.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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