2022
Major, R.; Wilczek, G.; Wiecek, J.; Gawlikowski, M.; Plutecka, H.; Kasperkiewicz, K.; Kot, M.; Pomorska, M.; Ostrowski, R.; Kopernik, M.
Hemocompatibile Thin Films Assessed under Blood Flow Shear Forces Journal Article
In: Molecules, vol. 27, no. 17, 2022, ISSN: 14203049.
@article{2-s2.0-85137844637,
title = {Hemocompatibile Thin Films Assessed under Blood Flow Shear Forces},
author = { R. Major and G. Wilczek and J. Wiecek and M. Gawlikowski and H. Plutecka and K. Kasperkiewicz and M. Kot and M. Pomorska and R. Ostrowski and M. Kopernik},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85137844637&doi=10.3390%2fmolecules27175696&partnerID=40&md5=ec553f2cb1e385bb319b67d9dca65767},
doi = {10.3390/molecules27175696},
issn = {14203049},
year = {2022},
date = {2022-01-01},
journal = {Molecules},
volume = {27},
number = {17},
publisher = {MDPI},
abstract = {The aim of this study was to minimize the risk of life-threatening thromboembolism in the ventricle through the use of a new biomimetic heart valve based on metal–polymer composites. Finite volume element simulations of blood adhesion to the material were carried out, encompassing radial flow and the cone and plane test together with determination of the effect of boundary conditions. Both tilt-disc and bicuspid valves do not have optimized blood flow due to their design based on rigid valve materials (leaflet made of pyrolytic carbon). The main objective was the development of materials with specific properties dedicated to contact with blood. Materials were evaluated by dynamic tests using blood, concentrates, and whole human blood. Hemostability tests under hydrodynamic conditions were related to the mechanical properties of thin-film materials obtained from tribological tests. The quality of the coatings was high enough to avoid damage to the coating even as they were exposed up to maximum loading. Analysis towards blood concentrates of the hydrogenated carbon sample and the nitrogen-doped hydrogenated carbon sample revealed that the interaction of the coating with erythrocytes was the strongest. Hemocompatibility evaluation under hydrodynamic conditions confirmed very good properties of the developed coatings. © 2022 by the authors.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The aim of this study was to minimize the risk of life-threatening thromboembolism in the ventricle through the use of a new biomimetic heart valve based on metal–polymer composites. Finite volume element simulations of blood adhesion to the material were carried out, encompassing radial flow and the cone and plane test together with determination of the effect of boundary conditions. Both tilt-disc and bicuspid valves do not have optimized blood flow due to their design based on rigid valve materials (leaflet made of pyrolytic carbon). The main objective was the development of materials with specific properties dedicated to contact with blood. Materials were evaluated by dynamic tests using blood, concentrates, and whole human blood. Hemostability tests under hydrodynamic conditions were related to the mechanical properties of thin-film materials obtained from tribological tests. The quality of the coatings was high enough to avoid damage to the coating even as they were exposed up to maximum loading. Analysis towards blood concentrates of the hydrogenated carbon sample and the nitrogen-doped hydrogenated carbon sample revealed that the interaction of the coating with erythrocytes was the strongest. Hemocompatibility evaluation under hydrodynamic conditions confirmed very good properties of the developed coatings. © 2022 by the authors.
2021
Kasperkiewicz, K.; Major, R.; Sypien, A.; Kot, M.; Dyner, M.; Major, Ł.; Byrski, A.; Kopernik, M.; Lackner, J. M.
Antibacterial optimization of highly deformed titanium alloys for spinal implants Journal Article
In: Molecules, vol. 26, no. 11, 2021, ISSN: 14203049, (2).
@article{2-s2.0-85107423588,
title = {Antibacterial optimization of highly deformed titanium alloys for spinal implants},
author = { K. Kasperkiewicz and R. Major and A. Sypien and M. Kot and M. Dyner and Ł. Major and A. Byrski and M. Kopernik and J.M. Lackner},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85107423588&doi=10.3390%2fmolecules26113145&partnerID=40&md5=38a80f80c8f5cca6e5674ad29003278f},
doi = {10.3390/molecules26113145},
issn = {14203049},
year = {2021},
date = {2021-01-01},
journal = {Molecules},
volume = {26},
number = {11},
publisher = {MDPI AG},
abstract = {The goal of the work was to develop materials dedicated to spine surgery that minimized the potential for infection originating from the transfer of bacteria during long surgeries. The bacteria form biofilms, causing implant loosening, pain and finally, a risk of paralysis for patients. Our strategy focused both on improvement of antibacterial properties against bacteria adhesion and on wear and corrosion resistance of tools for spine surgery. Further, a ~35% decrease in implant and tool dimensions was expected by introducing ultrahigh‐strength titanium alloys for less‐invasive surgeries. The tested materials, in the form of thin, multi‐layered coatings, showed nanocrystalline microstructures. Performed direct‐cytotoxicity studies (including lactate dehydrogenase activity measurement) showed that there was a low probability of adverse effects on surrounding SAOS‐2 (Homo sapiens bone osteosarcoma) cells. The microbiological studies (e.g.; ISO 22196 contact tests) showed that implanting Ag nanoparticles into Ti/TixN coatings inhibited the growth of E. coli and S. aureus cells and reduced their adhesion to the material surface. These findings suggest that Ag-nanoparticles present in implant coatings may potentially minimize infection risk and lower inherent stress. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.},
note = {2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The goal of the work was to develop materials dedicated to spine surgery that minimized the potential for infection originating from the transfer of bacteria during long surgeries. The bacteria form biofilms, causing implant loosening, pain and finally, a risk of paralysis for patients. Our strategy focused both on improvement of antibacterial properties against bacteria adhesion and on wear and corrosion resistance of tools for spine surgery. Further, a ~35% decrease in implant and tool dimensions was expected by introducing ultrahigh‐strength titanium alloys for less‐invasive surgeries. The tested materials, in the form of thin, multi‐layered coatings, showed nanocrystalline microstructures. Performed direct‐cytotoxicity studies (including lactate dehydrogenase activity measurement) showed that there was a low probability of adverse effects on surrounding SAOS‐2 (Homo sapiens bone osteosarcoma) cells. The microbiological studies (e.g.; ISO 22196 contact tests) showed that implanting Ag nanoparticles into Ti/TixN coatings inhibited the growth of E. coli and S. aureus cells and reduced their adhesion to the material surface. These findings suggest that Ag-nanoparticles present in implant coatings may potentially minimize infection risk and lower inherent stress. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
2016
Kot, M.; Büning, J.; Jankowska, W.; Drohojowska, J.; Szklarzewicz, T.
Development of ovary structures in the last larval and adult stages of psyllids (Insecta, Hemiptera, Sternorrhyncha: Psylloidea) Journal Article
In: Arthropod Structure and Development, vol. 45, no. 4, pp. 389-398, 2016, ISSN: 14678039, (3).
@article{2-s2.0-84973582255,
title = {Development of ovary structures in the last larval and adult stages of psyllids (Insecta, Hemiptera, Sternorrhyncha: Psylloidea)},
author = { M. Kot and J. Büning and W. Jankowska and J. Drohojowska and T. Szklarzewicz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973582255&doi=10.1016%2fj.asd.2016.04.004&partnerID=40&md5=904119161299c8708407f62b8d36a5ab},
doi = {10.1016/j.asd.2016.04.004},
issn = {14678039},
year = {2016},
date = {2016-01-01},
journal = {Arthropod Structure and Development},
volume = {45},
number = {4},
pages = {389-398},
publisher = {Elsevier Ltd},
abstract = {The development and organization of the ovaries of ten species from four Psylloidea families (Psyllidae; Triozidae; Aphalaridae and Liviidae) have been investigated. The ovaries of the last larval stage (i.e. fifth instar) of all examined species are filled with numerous clusters of cystocytes which undergo synchronous incomplete mitotic division. Cystocytes of the given cluster are arranged into a rosette with polyfusome in the centre. These clusters are associated with single somatic cells. At the end of the fifth instar, the clusters begin to separate from each other, forming spherical ovarioles which are surrounded by a single layer of somatic cells. In the ovarioles of very young females all cystocytes enter the prophase of meiosis and differentiate shortly thereafter into oocytes and trophocytes (nurse cells). Meanwhile, somatic cells differentiate into cells of the inner epithelial sheath surrounding the trophocytes and into the prefollicular cells that encompass the oocytes. During this final differentiation, the trophocytes lose their cell membranes and become syncytial. Oocytes remain cellular and most of them (termed arrested oocytes) do not grow. In the ovarioles of older females, one oocyte encompassed by its follicle cells starts growing, still connected to the syncytial tropharium by a nutritive cord. After the short phase of previtellogenesis alone, the oocyte enters its vitellogenic the growth phase in the vitellarium. At that time, the second oocyte may enter the vitellarium and start its previtellogenic growth. In the light of the obtained results, the phylogeny of psyllids, as well as phylogenetic relationships between taxa of Hemiptera: Sternorrhyncha are discussed. © 2016 Elsevier Ltd},
note = {3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The development and organization of the ovaries of ten species from four Psylloidea families (Psyllidae; Triozidae; Aphalaridae and Liviidae) have been investigated. The ovaries of the last larval stage (i.e. fifth instar) of all examined species are filled with numerous clusters of cystocytes which undergo synchronous incomplete mitotic division. Cystocytes of the given cluster are arranged into a rosette with polyfusome in the centre. These clusters are associated with single somatic cells. At the end of the fifth instar, the clusters begin to separate from each other, forming spherical ovarioles which are surrounded by a single layer of somatic cells. In the ovarioles of very young females all cystocytes enter the prophase of meiosis and differentiate shortly thereafter into oocytes and trophocytes (nurse cells). Meanwhile, somatic cells differentiate into cells of the inner epithelial sheath surrounding the trophocytes and into the prefollicular cells that encompass the oocytes. During this final differentiation, the trophocytes lose their cell membranes and become syncytial. Oocytes remain cellular and most of them (termed arrested oocytes) do not grow. In the ovarioles of older females, one oocyte encompassed by its follicle cells starts growing, still connected to the syncytial tropharium by a nutritive cord. After the short phase of previtellogenesis alone, the oocyte enters its vitellogenic the growth phase in the vitellarium. At that time, the second oocyte may enter the vitellarium and start its previtellogenic growth. In the light of the obtained results, the phylogeny of psyllids, as well as phylogenetic relationships between taxa of Hemiptera: Sternorrhyncha are discussed. © 2016 Elsevier Ltd
2013
Michalik, A.; Gołas, A.; Kot, M.; Wieczorek, K.; Szklarzewicz, T.
In: Arthropod Structure and Development, vol. 42, no. 6, pp. 531-538, 2013, ISSN: 14678039, (10).
@article{2-s2.0-84889562637,
title = {Endosymbiotic microorganisms in Adelges (Sacchiphantes) viridis (Insecta, Hemiptera, Adelgoidea: Adelgidae): Molecular characterization, ultrastructure and transovarial transmission},
author = { A. Michalik and A. Gołas and M. Kot and K. Wieczorek and T. Szklarzewicz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84889562637&doi=10.1016%2fj.asd.2013.09.004&partnerID=40&md5=e837a59a61ad77217753b4d921c9e3f6},
doi = {10.1016/j.asd.2013.09.004},
issn = {14678039},
year = {2013},
date = {2013-01-01},
journal = {Arthropod Structure and Development},
volume = {42},
number = {6},
pages = {531-538},
abstract = {The aim of this paper was to identify endosymbiotic microorganisms living in the body cavity of a Polish population of an aphid, Adelges (Sacchiphantes) viridis, as well as to describe their ultrastructure and mode of transmission between generations. Molecular data (amplification and sequencing of 16S rRNA genes) indicated that endosymbionts of A. (S.) viridis are Betaproteobacteria of the species ". Candidatus Vallotia virida". Endosymbiotic bacteria are rod-shaped and localized in the cytoplasm of specific cells, termed bacteriocytes, of host insects. Endosymbionts sharing the same bacteriocytes differ in the density of their cytoplasm. There are two morphotypes of endosymbiotic bacteria: with electron-dense cytoplasm and electron-translucent cytoplasm. Since only bacteria containing electron-dense cytoplasm were observed in the binary fusion stage, differences in density of the cytoplasm are probably due to changes in the cytoskeleton of bacteria during division. Endosymbionts of A. (S.) viridis are transovarially (i.e. via oocytes) transmitted from the mother to the offspring. © 2013 Elsevier Ltd.},
note = {10},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The aim of this paper was to identify endosymbiotic microorganisms living in the body cavity of a Polish population of an aphid, Adelges (Sacchiphantes) viridis, as well as to describe their ultrastructure and mode of transmission between generations. Molecular data (amplification and sequencing of 16S rRNA genes) indicated that endosymbionts of A. (S.) viridis are Betaproteobacteria of the species ". Candidatus Vallotia virida". Endosymbiotic bacteria are rod-shaped and localized in the cytoplasm of specific cells, termed bacteriocytes, of host insects. Endosymbionts sharing the same bacteriocytes differ in the density of their cytoplasm. There are two morphotypes of endosymbiotic bacteria: with electron-dense cytoplasm and electron-translucent cytoplasm. Since only bacteria containing electron-dense cytoplasm were observed in the binary fusion stage, differences in density of the cytoplasm are probably due to changes in the cytoskeleton of bacteria during division. Endosymbionts of A. (S.) viridis are transovarially (i.e. via oocytes) transmitted from the mother to the offspring. © 2013 Elsevier Ltd.
Szklarzewicz, T.; Kalandyk-Kołodziejczyk, M.; Kot, M.; Michalik, A.
In: Acta Zoologica, vol. 94, no. 2, pp. 184-192, 2013, ISSN: 00017272, (22).
@article{2-s2.0-84874769770,
title = {Ovary structure and transovarial transmission of endosymbiotic microorganisms in Marchalina hellenica (Insecta, Hemiptera, Coccomorpha: Marchalinidae)},
author = { T. Szklarzewicz and M. Kalandyk-Kołodziejczyk and M. Kot and A. Michalik},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84874769770&doi=10.1111%2fj.1463-6395.2011.00538.x&partnerID=40&md5=062f92494fa156df64ce96774453f1ce},
doi = {10.1111/j.1463-6395.2011.00538.x},
issn = {00017272},
year = {2013},
date = {2013-01-01},
journal = {Acta Zoologica},
volume = {94},
number = {2},
pages = {184-192},
abstract = {Szklarzewicz, T., Kalandyk-Kolodziejczyk, M., Kot, M. and Michalik, A. 2011. Ovary structure and transovarial transmission of endosymbiotic microorganisms in Marchalina hellenica (Insecta; Hemiptera; Coccomorpha: Marchalinidae). -Acta Zoologica (Stockholm) 00:1-9. The paired ovaries of Marchalina hellenica are composed of about 200 ovarioles of telotrophic type. In each ovariole, a trophic chamber, vitellarium and ovariolar stalk can be distinguished. The tropharia comprise trophocytes and early previtellogenic oocytes (termed arrested oocytes) or trophocytes only. The arrested oocytes are not capable of further development. In the vitellaria, single oocytes develop that are connected to the tropharium by means of broad nutritive cords. The number of germ cells (trophocytes and oocytes) constituting ovarioles is not constant and may range between 25 and 32. Numerous endosymbiotic bacteria occur in the cytoplasm of trophocytes. The endosymbionts are transported via nutritive cords to the developing oocyte. The obtained results are discussed in a phylogenetic context. © 2011 The Royal Swedish Academy of Sciences.},
note = {22},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Szklarzewicz, T., Kalandyk-Kolodziejczyk, M., Kot, M. and Michalik, A. 2011. Ovary structure and transovarial transmission of endosymbiotic microorganisms in Marchalina hellenica (Insecta; Hemiptera; Coccomorpha: Marchalinidae). -Acta Zoologica (Stockholm) 00:1-9. The paired ovaries of Marchalina hellenica are composed of about 200 ovarioles of telotrophic type. In each ovariole, a trophic chamber, vitellarium and ovariolar stalk can be distinguished. The tropharia comprise trophocytes and early previtellogenic oocytes (termed arrested oocytes) or trophocytes only. The arrested oocytes are not capable of further development. In the vitellaria, single oocytes develop that are connected to the tropharium by means of broad nutritive cords. The number of germ cells (trophocytes and oocytes) constituting ovarioles is not constant and may range between 25 and 32. Numerous endosymbiotic bacteria occur in the cytoplasm of trophocytes. The endosymbionts are transported via nutritive cords to the developing oocyte. The obtained results are discussed in a phylogenetic context. © 2011 The Royal Swedish Academy of Sciences.
2010
Kot, M.; Karcz, W.; Zaborska, W.
In: Bioorganic Chemistry, vol. 38, no. 3, pp. 132-137, 2010, ISSN: 00452068, (46).
@article{2-s2.0-77949916345,
title = {5-Hydroxy-1,4-naphthoquinone (juglone) and 2-hydroxy-1,4-naphthoquinone (lawsone) influence on jack bean urease activity: Elucidation of the difference in inhibition activity},
author = { M. Kot and W. Karcz and W. Zaborska},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77949916345&doi=10.1016%2fj.bioorg.2010.02.002&partnerID=40&md5=6cd4e38a38b09b529ba4145fd7b04157},
doi = {10.1016/j.bioorg.2010.02.002},
issn = {00452068},
year = {2010},
date = {2010-01-01},
journal = {Bioorganic Chemistry},
volume = {38},
number = {3},
pages = {132-137},
abstract = {The aim of this study was elucidation of the difference in inhibition influence of 5-hydroxy-1,4-naphthoquinone (juglone) and 2-hydroxy-1,4-naphthoquinone (lawsone) on jack bean urease activity. It was found that juglone acted as a strong, time and concentration dependent inactivator of urease. On the contrary, lawsone showed an inconsiderable inhibition influence. The reactivation of juglone modified urease showed the participation of reversible and irreversible contribution in the inactivation. In the presence of an excess of DTT, urease inactivated by juglone regained 70% of its activity. The reversible inactivation was attributed to oxidation of the essential urease thiols by reactive oxygen species (ROS) realizing during reduction of juglone to seminaphthoquinone. Presence of hydrogen peroxide in the incubation system was proved by direct determination and by application of catalase. The irreversible contribution in the inhibition was assumed as an arylation of urease thiol groups by juglone. The insignificant urease inhibition by lawsone was concluded as an effect of a low hydrogen peroxide generation and lawsone resistance for reaction with protein thiols. It was found that lawsone well reacted with l-cysteine, poorly with glutathione and hardly with urease thiols. The observed sequence was arranged according the rule the more complex thiol the less susceptible for reaction with lawsone. On the other hand, juglone displayed an excellent reactivity towards both thiols and urease. Thus, this indicated a significance of a steric hindrance which appeared when the hydroxyl group changing position from 5 in juglone (5-hydroxy-1;4-naphthoquinone) to 2 in lawsone (2-hydroxy-1;4-naphthoquinone). © 2010 Elsevier Inc. All rights reserved.},
note = {46},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The aim of this study was elucidation of the difference in inhibition influence of 5-hydroxy-1,4-naphthoquinone (juglone) and 2-hydroxy-1,4-naphthoquinone (lawsone) on jack bean urease activity. It was found that juglone acted as a strong, time and concentration dependent inactivator of urease. On the contrary, lawsone showed an inconsiderable inhibition influence. The reactivation of juglone modified urease showed the participation of reversible and irreversible contribution in the inactivation. In the presence of an excess of DTT, urease inactivated by juglone regained 70% of its activity. The reversible inactivation was attributed to oxidation of the essential urease thiols by reactive oxygen species (ROS) realizing during reduction of juglone to seminaphthoquinone. Presence of hydrogen peroxide in the incubation system was proved by direct determination and by application of catalase. The irreversible contribution in the inhibition was assumed as an arylation of urease thiol groups by juglone. The insignificant urease inhibition by lawsone was concluded as an effect of a low hydrogen peroxide generation and lawsone resistance for reaction with protein thiols. It was found that lawsone well reacted with l-cysteine, poorly with glutathione and hardly with urease thiols. The observed sequence was arranged according the rule the more complex thiol the less susceptible for reaction with lawsone. On the other hand, juglone displayed an excellent reactivity towards both thiols and urease. Thus, this indicated a significance of a steric hindrance which appeared when the hydroxyl group changing position from 5 in juglone (5-hydroxy-1;4-naphthoquinone) to 2 in lawsone (2-hydroxy-1;4-naphthoquinone). © 2010 Elsevier Inc. All rights reserved.
2009
Zaborska, W.; Karcz, W.; Kot, M.; Juszkiewicz, A.
Modification of jack bean urease thiols by thiosulphinates contained in garlic extract: DTNB titration studies Journal Article
In: Food Chemistry, vol. 112, no. 1, pp. 42-45, 2009, ISSN: 03088146, (7).
@article{2-s2.0-47749141457,
title = {Modification of jack bean urease thiols by thiosulphinates contained in garlic extract: DTNB titration studies},
author = { W. Zaborska and W. Karcz and M. Kot and A. Juszkiewicz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-47749141457&doi=10.1016%2fj.foodchem.2008.05.029&partnerID=40&md5=dac671bec0e7f0f37fadc4eac06c01e0},
doi = {10.1016/j.foodchem.2008.05.029},
issn = {03088146},
year = {2009},
date = {2009-01-01},
journal = {Food Chemistry},
volume = {112},
number = {1},
pages = {42-45},
abstract = {The reactivity of the thiol groups in urease with thiosulphinate contained in garlic extract was spectroscopically characterised. The enzyme was incubated with the garlic extract and the reaction progress curves were recorded in the presence of thiol-selective reagent 5,5′-dithiobis(2-nitrobenzoic acid). Simultaneously the enzyme residual activity was also determined. The process was studied in 50 mM phosphate buffer, at pH 7.8 and ambient temperature. It was found that thiosulphinates act as time- and concentration-dependent inactivators of urease. The observed decrease of the enzyme activity corresponds to the number of the urease thiols modified by thiosulphinates. The modification of half of all the urease thiols (18 of 36) causes a slight (only 8-10%) decrease of the catalytic activity. The modification of the remaining 18 thiols results in significant disturbance of urease action until complete loss of the catalytic function occurs. This provides the evidence that Cys592, the critical residue for urease activity, belongs to the enzyme thiols, which are less reactive and more resistant to chemical modification than the other thiols. © 2008 Elsevier Ltd. All rights reserved.},
note = {7},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The reactivity of the thiol groups in urease with thiosulphinate contained in garlic extract was spectroscopically characterised. The enzyme was incubated with the garlic extract and the reaction progress curves were recorded in the presence of thiol-selective reagent 5,5′-dithiobis(2-nitrobenzoic acid). Simultaneously the enzyme residual activity was also determined. The process was studied in 50 mM phosphate buffer, at pH 7.8 and ambient temperature. It was found that thiosulphinates act as time- and concentration-dependent inactivators of urease. The observed decrease of the enzyme activity corresponds to the number of the urease thiols modified by thiosulphinates. The modification of half of all the urease thiols (18 of 36) causes a slight (only 8-10%) decrease of the catalytic activity. The modification of the remaining 18 thiols results in significant disturbance of urease action until complete loss of the catalytic function occurs. This provides the evidence that Cys592, the critical residue for urease activity, belongs to the enzyme thiols, which are less reactive and more resistant to chemical modification than the other thiols. © 2008 Elsevier Ltd. All rights reserved.
2007
Zaborska, W.; Krajewska, B.; Kot, M.; Karcz, W.
Quinone-induced inhibition of urease: Elucidation of its mechanisms by probing thiol groups of the enzyme Journal Article
In: Bioorganic Chemistry, vol. 35, no. 3, pp. 233-242, 2007, ISSN: 00452068, (60).
@article{2-s2.0-34247473954,
title = {Quinone-induced inhibition of urease: Elucidation of its mechanisms by probing thiol groups of the enzyme},
author = { W. Zaborska and B. Krajewska and M. Kot and W. Karcz},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34247473954&doi=10.1016%2fj.bioorg.2006.11.001&partnerID=40&md5=e10214f86111b099bd03d79f3dbb008f},
doi = {10.1016/j.bioorg.2006.11.001},
issn = {00452068},
year = {2007},
date = {2007-01-01},
journal = {Bioorganic Chemistry},
volume = {35},
number = {3},
pages = {233-242},
abstract = {In this work we studied the reaction of four quinones, 1,4-benzoquinone (1;4-BQ), 2,5-dimethyl-1,4-benzoquinone (2;5-DM-1;4-BQ), tetrachloro-1,4-benzoquinone (TC-1;4-BQ) and 1,4-naphthoquinone (1;4-NQ) with jack bean urease in phosphate buffer, pH 7.8. The enzyme was allowed to react with different concentrations of the quinones during different incubation times in aerobic conditions. Upon incubation the samples had their residual activities assayed and their thiol content titrated. The titration carried out with use of 5,5′-di-thiobis(2-nitrobenzoic) acid was done to examine the involvement of urease thiol groups in the quinone-induced inhibition. The quinones under investigation showed two distinct patterns of behaviour, one by 1,4-BQ, 2,5-DM-1,4-BQ and TC-1,4-BQ, and the other by 1,4-NQ. The former consisted of a concentration-dependent inactivation of urease where the enzyme-inhibitor equilibrium was achieved in no longer than 10 min, and of the residual activity of the enzyme being linearly correlated with the number of modified thiols in urease. We concluded that arylation of the thiols in urease by these quinones resulting in conformational changes in the enzyme molecule is responsible for the inhibition. The other pattern of behaviour observed for 1,4-NQ consisted of time- and concentration-dependent inactivation of urease with a nonlinear residual activity-modified thiols dependence. This suggests that in 1,4-NQ inhibition, in addition to the arylation of thiols, operative are other reactions, most likely oxidations of thiols provoked by 1,4-NQ-catalyzed redox cycling. In terms of the inhibitory strength, the quinones studied formed a series: 1,4-NQ ≈ 2,5-DM-1,4-BQ < 1,4-BQ < TC-1,4-BQ. © 2006 Elsevier Inc. All rights reserved.},
note = {60},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this work we studied the reaction of four quinones, 1,4-benzoquinone (1;4-BQ), 2,5-dimethyl-1,4-benzoquinone (2;5-DM-1;4-BQ), tetrachloro-1,4-benzoquinone (TC-1;4-BQ) and 1,4-naphthoquinone (1;4-NQ) with jack bean urease in phosphate buffer, pH 7.8. The enzyme was allowed to react with different concentrations of the quinones during different incubation times in aerobic conditions. Upon incubation the samples had their residual activities assayed and their thiol content titrated. The titration carried out with use of 5,5′-di-thiobis(2-nitrobenzoic) acid was done to examine the involvement of urease thiol groups in the quinone-induced inhibition. The quinones under investigation showed two distinct patterns of behaviour, one by 1,4-BQ, 2,5-DM-1,4-BQ and TC-1,4-BQ, and the other by 1,4-NQ. The former consisted of a concentration-dependent inactivation of urease where the enzyme-inhibitor equilibrium was achieved in no longer than 10 min, and of the residual activity of the enzyme being linearly correlated with the number of modified thiols in urease. We concluded that arylation of the thiols in urease by these quinones resulting in conformational changes in the enzyme molecule is responsible for the inhibition. The other pattern of behaviour observed for 1,4-NQ consisted of time- and concentration-dependent inactivation of urease with a nonlinear residual activity-modified thiols dependence. This suggests that in 1,4-NQ inhibition, in addition to the arylation of thiols, operative are other reactions, most likely oxidations of thiols provoked by 1,4-NQ-catalyzed redox cycling. In terms of the inhibitory strength, the quinones studied formed a series: 1,4-NQ ≈ 2,5-DM-1,4-BQ < 1,4-BQ < TC-1,4-BQ. © 2006 Elsevier Inc. All rights reserved.