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Lee W, Marcotullio S, Yeom H, Son H, Kim TH, Lee Y. Reaction kinetics and degradation efficiency of halogenated methylparabens during ozonation and UV/H 2O 2 treatment of drinking water and wastewater effluent. J Hazard Mater 2022; 427:127878. [PMID: 34872780 DOI: 10.1016/j.jhazmat.2021.127878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 06/13/2023]
Abstract
This study investigated the reaction kinetics and degradation efficiency of methylparaben and its halogenated products (Cl-, Br-, Cl,Cl-, Br,Cl-, and Br,Br-methylparabens) during ozonation and UV254/H2O2 treatment. Second-order rate constants for reactions of the parabens with ozone and •OH were [Formula: see text] = 107 - 108 M-1 s-1 and [Formula: see text] = (2.3 - 4.3)× 109 M-1 s-1 at pH 7. Species-specific [Formula: see text] values of the protonated and deprotonated parabens were closely related to phenol ring substituent effects via quantitative structure-activity relationships with other substituted phenols. The UV photolysis rate of the parabens [kUV = (2.4 - 7.2)× 10-4 cm2 mJ-1] depended on the halogenation state of the paraben and solution pH, from which species-specific quantum yields were also determined. In simulated treatments of drinking water and wastewater effluent, the parabens were efficiently eliminated during ozonation, requiring a specific ozone dose of > 0.26 gO3/gDOC for > 97% degradation. During UV/H2O2 treatment with 10 mg L-1 H2O2, the degradation levels were > 90% at a UV fluence of 2000 mJ cm-2, except for Cl,Cl-methylparaben. Kinetic models based on the obtained reaction kinetic parameters could successfully predict the degradation levels of the parabens. Overall, ozonation and UV/H2O2 were effective in controlling parabens and their halogenated products during advanced water treatment.
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Affiliation(s)
- Woorim Lee
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea; Busan Water Quality Institute, Gimhae, 50804, Republic of Korea
| | - Sandro Marcotullio
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea
| | - Hoonsik Yeom
- Busan Water Quality Institute, Gimhae, 50804, Republic of Korea
| | - Heejong Son
- Busan Water Quality Institute, Gimhae, 50804, Republic of Korea
| | - Tae-Hun Kim
- Research Division for Industry and Environment, Korea Atomic Energy Research Institute, Jeongeup, 56212, Republic of Korea
| | - Yunho Lee
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea.
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Wang J, Yeom H, Humrickhouse P, Sridharan K, Corradini M. Effectiveness of Cr-Coated Zr-Alloy Clad in Delaying Fuel Degradation for a PWR During a Station Blackout Event. NUCL TECHNOL 2019. [DOI: 10.1080/00295450.2019.1649566] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- J. Wang
- University of Wisconsin-Madison, Department of Nuclear Engineering and Engineering Physics, Madison, Wisconsin
| | - H. Yeom
- University of Wisconsin-Madison, Department of Nuclear Engineering and Engineering Physics, Madison, Wisconsin
| | | | - K. Sridharan
- University of Wisconsin-Madison, Department of Nuclear Engineering and Engineering Physics, Madison, Wisconsin
| | - M. Corradini
- University of Wisconsin-Madison, Department of Nuclear Engineering and Engineering Physics, Madison, Wisconsin
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Yeom H. THE ASSOCIATION AMONG AGING-RELATED STEREOTYPE, FAMILY FUNCTION, AND HEALTHY BEHAVIOR IN MIDDLE-AGED KOREAN. Innov Aging 2018. [DOI: 10.1093/geroni/igy031.3702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- H Yeom
- Chungnam National University
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Stange G, Yeom H, Semerau B, Sridharan K, Corradini M. A Study of Nanoparticle Surface Modification Effects on Pool Boiling Critical Heat Flux. NUCL TECHNOL 2017. [DOI: 10.13182/nt13-a16980] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- G. Stange
- University of Wisconsin, Engineering Physics and Nuclear Engineering Department 1500 Engineering Drive, Madison, Wisconsin 53706
| | - H. Yeom
- University of Wisconsin, Engineering Physics and Nuclear Engineering Department 1500 Engineering Drive, Madison, Wisconsin 53706
| | - B. Semerau
- University of Wisconsin, Engineering Physics and Nuclear Engineering Department 1500 Engineering Drive, Madison, Wisconsin 53706
| | - K. Sridharan
- University of Wisconsin, Engineering Physics and Nuclear Engineering Department 1500 Engineering Drive, Madison, Wisconsin 53706
| | - M. Corradini
- University of Wisconsin, Engineering Physics and Nuclear Engineering Department 1500 Engineering Drive, Madison, Wisconsin 53706
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Lyons TJ, Nersissian A, Huang H, Yeom H, Nishida CR, Graden JA, Gralla EB, Valentine JS. The metal binding properties of the zinc site of yeast copper-zinc superoxide dismutase: implications for amyotrophic lateral sclerosis. J Biol Inorg Chem 2000; 5:189-203. [PMID: 10819464 DOI: 10.1007/s007750050363] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have investigated factors that influence the properties of the zinc binding site in yeast copper-zinc superoxide dismutase (CuZnSOD). The properties of yeast CuZnSOD are essentially invariant from pH 5 to pH 9. However, below this pH range there is a change in the nature of the zinc binding site which can be interpreted as either (1) a change in metal binding affinity from strong to weak, (2) the expulsion of the metal bound at this site, or (3) a transition from a normal distorted tetrahedral ligand orientation to a more symmetric arrangement of ligands. This change is strongly reminiscent of a similar pH-induced transition seen for the bovine protein and, based on the data presented herein, is proposed to be a property that is conserved among CuZnSODs. The transition demonstrated for the yeast protein is not only sensitive to the pH of the buffering solution but also to the occupancy and redox status of the adjacent copper binding site. Furthermore, we have investigated the effect of single site mutations on the pH- and redox-sensitivity of Co2+ binding at the zinc site. Each of the mutants H46R, H48Q, H63A, H63E, H80C, G85R, and D83H is capable of binding Co2+ to a zinc site with a distorted tetrahedral geometry similar to that of wild-type. However, they do so only if Cu+ is bound at the copper site or if the pH in raised to near physiological levels, indicating that the change at the zinc binding site seen in the wild-type is conserved in the mutants, albeit with an altered pKa. The mutants H71C and D83A did not bind Co2+ in a wild-type-like fashion under any of the conditions tested. This study reveals that the zinc binding site is exquisitely sensitive to changes in the protein environment. Since three of the mutant yeast proteins investigated here contain mutations analogous to those that cause ALS (amyotrophic lateral sclerosis) in humans, this finding implicates improper metal binding as a mechanism by which CuZnSOD mutants exert their toxic gain of function.
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Affiliation(s)
- T J Lyons
- Department of Molecular Biology, University of Missouri-Columbia, 65211, USA
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Deng TJ, Proniewicz LM, Kincaid JR, Yeom H, Macdonald ID, Sligar SG. Resonance Raman studies of cytochrome P450BM3 and its complexes with exogenous ligands. Biochemistry 1999; 38:13699-706. [PMID: 10521277 DOI: 10.1021/bi991287j] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Resonance Raman spectra are reported for both the heme domain and holoenzyme of cytochrome P450BM3 in the resting state and for the ferric NO, ferrous CO, and ferrous NO adducts in the absence and presence of the substrate, palmitate. Comparison of the spectrum of the palmitate-bound form of the heme domain with that of the holoenzyme indicates that the presence of the flavin reductase domain alters the structure of the heme domain in such a way that water accessibility to the distal pocket is greater for the holoenzyme, a result that is consistent with analogous studies of cytochrome P450cam. The data for the exogenous ligand adducts are compared to those previously reported for corresponding derivatives of cytochrome P450cam and document significant and important differences for the two proteins. Specifically, while the binding of substrate induces relatively dramatic changes in the nu(Fe-XY) modes of the ferrous CO, ferric NO, and ferrous NO derivatives of cytochrome P450cam, no significant changes are observed for the corresponding derivatives of cytochrome P450BM3 upon binding of palmitate. In fact, the spectral data for substrate-free cytochrome P450BM3 provide evidence for distortion of the Fe-XY fragment, even in the absence of substrate. This apparent distortion, which is nonexistent in the case of substrate-free cytochrome P450cam, is most reasonably attributed to interaction of the Fe-XY fragment with the F87 phenylalanine side chain. This residue is known to lie very close to the heme iron in the substrate-free derivative of cytochrome P450BM3 and has been suggested to prevent hydroxylation of the terminal, omega, position of long-chain fatty acids.
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Affiliation(s)
- T J Deng
- Beckman Institute for Advanced Science and Technology, Department of Biochemistry, University of Illinois, Urbana 61081, USA
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Lee H, Yeom H, Kim YG, Yoon CN, Jin C, Choi JS, Kim BR, Kim DH. Structure-related inhibition of human hepatic caffeine N3-demethylation by naturally occurring flavonoids. Biochem Pharmacol 1998; 55:1369-75. [PMID: 10076527 DOI: 10.1016/s0006-2952(97)00644-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The effects of flavonoids on caffeine N3-demethylation, a marker activity of CYP1A2, in human liver microsomes were investigated to elucidate the inhibition mechanism and the structure-activity relationship. Caffeine N3-demethylase activity was inhibited by the presence of various flavonoids, whose structures seem to be closely related to the degree of inhibition. Among twenty-one compounds tested, the most active was chrysin with an IC50 value of 0.2 microM. Others had IC50 values ranging from 1 to more than 500 microM. Kinetic analysis revealed that the mechanism of inhibition varied among the flavonoids. The inhibitory effect was postulated to be governed by factors such as the number of hydroxyl groups and glycosylation of these free hydroxyl groups. An increase in the number of free hydroxyl groups reduced the inhibitory effect on P450 activity. Analysis of the quantitative structure-activity relationship (QSAR) showed that the volume to surface area ratio was the most effective factor on the inhibition of caffeine N3-demethylation, and the electron densities on the C3 and C4' atoms exercised significant influence on the inhibitory effect. The calculated inhibitory effect of flavonoids on CYP1A2 activity was highly correlated with the antimutagenicity of flavonoids in 2-amino-3,4-dimethylimidazo[4,5-flquinoline (MelQ)-induced umu response.
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Affiliation(s)
- H Lee
- Doping Control Center, Korea Institute of Science and Technology, Chungryang, Seoul, Korea
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Abstract
A mutation at the surface of the substrate access channel which dramatically decreases the affinity for some fatty acids in P450(BM-3) was discovered by random mutagenesis. The mutation introduced, proline-25 to glutamine, is in close proximity to the arginine-47 residue thought to be responsible for the initial docking of fatty acid substrates. The P25Q mutant displays an affinity for palmitate which is approximately 100-fold weaker than the wild-type enzyme. In addition to its altered substrate affinity, P25Q also exhibits altered hydroxylation specificity and carbon monoxide recombination kinetics in the substrate-free form.
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Affiliation(s)
- S A Maves
- Beckman Institute for Advanced Science and Technology and Department of Biochemistry, University of Illinois, Urbana 61801, USA
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Abstract
A highly conserved acid residue is found in the I-helix of most cytochrome P450s and has been suggested to play a critical function in oxygen activation and substrate hydroxylation in these monooxygenases. We have investigated this hypothesis for cytochrome P450BM-3 by replacing the naturally occuring glutamate at position 267 with a glutamine residue. In the case of P450BM-3, mutation of the glutamate to glutamine as position 267 drastically reduces the catalytic activity of the enzyme when palmitate is used as a substrate for hydroxylation. On the other hand, the activity change toward laurate hydroxylation is relatively small. The much slower catalytic turnover by the mutant enzyme in palmitate hydroxylation compared with wild type allows the observation of a new spectral intermediate in the hemoprotein. This intermediate is similar to that observed in the corresponding active site acid-to-amide replacement in cytochrome P450cam (N. C. Gerber and S. G. Sligar (1994) J. Biol. Chem. 269, 4260-4266). Also, in analogy with P450cam, this mutation does not lead to any side oxidation processes which produce hydrogen peroxide. Interestingly, however, the alteration in the active site structure which is implied by the change in regio specificity may also effect substrate packing thus leading to the uncoupling of the enzyme to produce additional water rather than a commitment to substrate oxidation. In addition, the distribution of hydroxylation products is altered by this mutation, suggesting some perturbation of the recognition property in P450BM-3.
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Affiliation(s)
- H Yeom
- Beckman Institute for Advanced Science and Technology, Department of Biochemistry, University of Illinois, Urbana 61801, USA
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Abstract
The kinetics of carbon monoxide binding to cytochrome P450BM-3 in the presence and absence of substrate has been investigated using flash photolysis. The second order kinetics for CO association with the substrate-free form of the protein appear biphasic. Deconvolution into two exponentials yields fast and slow rate constants of 11.1 +/- 0.6 x 10(6) M-1 s-1 and 3.5 +/- 0.2 x 10(6) M-1 s-1, respectively with 52% of the signal being attributed to the fast phase. Interestingly, upon binding of a substrate such as laurate, the second order kinetics become monophasic, with a value of 3.5 x 10(6) M-1 s-1, which are similar to the slow rate found in the substrate-free form of the protein. We have also examined the geminate CO rebinding kinetics in the presence and absence of various substrates. In the substrate-free form of the overall geminate yield is 30%, and addition of a substrate increases the geminate yield to roughly 50%. Both the substrate-free and substrate-bound forms exhibit complex geminate kinetics which cannot be described by a simple three-state kinetic model. Extension of this model to include four states is required. The addition of substrate causes an increase in the geminate rate constants resulting in a larger geminate amplitude when compared to the substrate-free form. There is also evidence for a correlation between the volume occupied by the substrate and the geminate rate constants. These results are discussed in terms of substrate-dependent conformational changes in cytochrome P450BM-3 and the overall energy landscape of the hemoprotein which couples to conformer equilibria.
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Affiliation(s)
- M A McLean
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana 61801, USA
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Abstract
Cytochrome P450BM-3, a catalytically self-sufficient monooxygenase from Bacillus megaterium, catalyzes the omega-n (n = 1-3) hydroxylation of fatty acids in the presence of O2 and NADPH. Like most other P450s, cytochrome P450BM-3 contains a threonine residue (Thr268) in the distal I helix thought to be important for O2 binding and activation. Thr268 has been converted to alanine and the enzymatic properties and heme domain crystal structure determined. Using sodium laurate as the substrate, the mutant exhibited slower rates of O2 and NADPH consumption. In addition, electron transfer is uncoupled from substrate hydroxylation as evidenced by the greater production of water and peroxide in the mutant compared to the wild-type enzyme. The crystal structure of the mutant reveals that the only changes in structure are confined to the site of mutation. These data indicate an important role for Thr268 in O2 binding and activation in the metabolism of sodium laurate by cytochrome P450BM-3.
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Affiliation(s)
- H Yeom
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana 61801, USA
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Lyons T, Nishida C, Yeom H, Valentine J. Redesign of yeast Cu,Zn-superoxide dismutase: Probing the structure-function relationship and designing mimics of other metalloenzymes. J Inorg Biochem 1995. [DOI: 10.1016/0162-0134(95)97767-k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Yeom H, Lu Y, Andrew C, Sanders-Loehr J, Gralla E, Valentine J. Probing the active site of yeast copper-zinc SOD with cysteine. J Inorg Biochem 1993. [DOI: 10.1016/0162-0134(93)85171-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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