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D'Antonio EL, D'Antonio J, de Serrano V, Gracz H, Thompson MK, Ghiladi RA, Bowden EF, Franzen S. Functional consequences of the creation of an Asp-His-Fe triad in a 3/3 globin. Biochemistry 2011; 50:9664-80. [PMID: 21950839 DOI: 10.1021/bi201368u] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The proximal side of dehaloperoxidase-hemoglobin A (DHP A) from Amphitrite ornata has been modified via site-directed mutagenesis of methionine 86 into aspartate (M86D) to introduce an Asp-His-Fe triad charge relay. X-ray crystallographic structure determination of the metcyano forms of M86D [Protein Data Bank (PDB) entry 3MYN ] and M86E (PDB entry 3MYM ) mutants reveal the structural origins of a stable catalytic triad in DHP A. A decrease in the rate of H(2)O(2) activation as well as a lowered reduction potential versus that of the wild-type enzyme was observed in M86D. One possible explanation for the significantly lower activity is an increased affinity for the distal histidine in binding to the heme Fe to form a bis-histidine adduct. Resonance Raman spectroscopy demonstrates a pH-dependent ligation by the distal histidine in M86D, which is indicative of an increased trans effect. At pH 5.0, the heme Fe is five-coordinate, and this structure resembles the wild-type DHP A resting state. However, at pH 7.0, the distal histidine appears to form a six-coordinate ferric bis-histidine (hemichrome) adduct. These observations can be explained by the effect of the increased positive charge on the heme Fe on the formation of a six-coordinate low-spin adduct, which inhibits the ligation and activation of H(2)O(2) as required for peroxidase activity. The results suggest that the proximal charge relay in peroxidases regulate the redox potential of the heme Fe but that the trans effect is a carefully balanced property that can both activate H(2)O(2) and attract ligation by the distal histidine. To understand the balance of forces that modulate peroxidase reactivity, we studied three M86 mutants, M86A, M86D, and M86E, by spectroelectrochemistry and nuclear magnetic resonance spectroscopy of (13)C- and (15)N-labeled cyanide adducts as probes of the redox potential and of the trans effect in the heme Fe, both of which can be correlated with the proximity of negative charge to the N(δ) hydrogen of the proximal histidine, consistent with an Asp-His-Fe charge relay observed in heme peroxidases.
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Thompson MK, Franzen S, Davis MF, Oliver RC, Krueger JK. Dehaloperoxidase-hemoglobin from Amphitrite ornata is primarily a monomer in solution. J Phys Chem B 2011; 115:4266-72. [PMID: 21417234 DOI: 10.1021/jp201156r] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The crystal structures of the dehaloperoxidase-hemoglobin from A. ornata (DHP A) each report a crystallographic dimer in the unit cell. Yet, the largest dimer interface observed is 450 Å(2), an area significantly smaller than the typical value of 1200-2000 Å(2) and in contrast to the extensive interface region of other known dimeric hemoglobins. To examine the oligomerization state of DHP A in solution, we used gel permeation by fast protein liquid chromatography and small-angle X-ray scattering (SAXS). Gel permeation experiments demonstrate that DHP A elutes as a monomer (15.5 kDa) and can be separated from green fluorescent protein, which has a molar mass of 27 kDa, near the 31 kDa expected for the DHP A dimer. By SAXS, we found that DHP A is primarily monomeric in solution, but with a detectable level of dimer (~10%), under all conditions studied up to a protein concentration of 3.0 mM. These concentrations are likely 10-100-fold lower than the K(d) for dimer formation. Additionally, there was no significant effect either on the overall conformation of DHP A or its monomer-dimer equilibrium upon addition of the DHP A inhibitor, 4-iodophenol.
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Nicoletti FP, Thompson MK, Franzen S, Smulevich G. Degradation of sulfide by dehaloperoxidase-hemoglobin from Amphitrite ornata. J Biol Inorg Chem 2011; 16:611-9. [DOI: 10.1007/s00775-011-0762-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 01/26/2011] [Indexed: 10/18/2022]
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Thompson MK, Franzen S, Ghiladi RA, Reeder BJ, Svistunenko DA. Decay of Compound ES in Dehaloperoxidase-Hemoglobin. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.1275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Plummer AM, Thompson MK, Franzen S. Making Substrates Out of Inhibitors: Distal Cavity Mutations in Dehaloperoxidase from Amphitrite Ornata. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.1424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Thompson MK, Davis MF, de Serrano V, Nicoletti FP, Howes BD, Smulevich G, Franzen S. Internal binding of halogenated phenols in dehaloperoxidase-hemoglobin inhibits peroxidase function. Biophys J 2010; 99:1586-95. [PMID: 20816071 DOI: 10.1016/j.bpj.2010.05.041] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 05/11/2010] [Accepted: 05/17/2010] [Indexed: 10/19/2022] Open
Abstract
Dehaloperoxidase (DHP) from the annelid Amphitrite ornata is a catalytically active hemoglobin-peroxidase that possesses a unique internal binding cavity in the distal pocket above the heme. The previously published crystal structure of DHP shows 4-iodophenol bound internally. This led to the proposal that the internal binding site is the active site for phenol oxidation. However, the native substrate for DHP is 2,4,6-tribromophenol, and all attempts to bind 2,4,6-tribromophenol in the internal site under physiological conditions have failed. Herein, we show that the binding of 4-halophenols in the internal pocket inhibits enzymatic function. Furthermore, we demonstrate that DHP has a unique two-site competitive binding mechanism in which the internal and external binding sites communicate through two conformations of the distal histidine of the enzyme, resulting in nonclassical competitive inhibition. The same distal histidine conformations involved in DHP function regulate oxygen binding and release during transport and storage by hemoglobins and myoglobins. This work provides further support for the hypothesis that DHP possesses an external binding site for substrate oxidation, as is typical for the peroxidase family of enzymes.
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Thompson MK, Franzen S, Ghiladi RA, Reeder BJ, Svistunenko DA. Compound ES of Dehaloperoxidase Decays via Two Alternative Pathways Depending on the Conformation of the Distal Histidine. J Am Chem Soc 2010; 132:17501-10. [DOI: 10.1021/ja106620q] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ma H, Thompson MK, Gaff J, Franzen S. Kinetic Analysis of a Naturally Occurring Bioremediation Enzyme: Dehaloperoxidase-Hemoglobin from Amphitrite ornata. J Phys Chem B 2010; 114:13823-9. [DOI: 10.1021/jp1014516] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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D'Antonio J, D'Antonio EL, Thompson MK, Bowden EF, Franzen S, Smirnova T, Ghiladi RA. Spectroscopic and mechanistic investigations of dehaloperoxidase B from Amphitrite ornata. Biochemistry 2010; 49:6600-16. [PMID: 20545299 DOI: 10.1021/bi100407v] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dehaloperoxidase (DHP) from the terebellid polychaete Amphitrite ornata is a bifunctional enzyme that possesses both hemoglobin and peroxidase activities. Of the two DHP isoenzymes identified to date, much of the recent focus has been on DHP A, whereas very little is known pertaining to the activity, substrate specificity, mechanism of function, or spectroscopic properties of DHP B. Herein, we report the recombinant expression and purification of DHP B, as well as the details of our investigations into its catalytic cycle using biochemical assays, stopped-flow UV-visible, resonance Raman, and rapid freeze-quench electron paramagnetic resonance spectroscopies, and spectroelectrochemistry. Our experimental design reveals mechanistic insights and kinetic descriptions of the dehaloperoxidase mechanism which have not been previously reported for isoenzyme A. Namely, we demonstrate a novel reaction pathway in which the products of the oxidative dehalogenation of trihalophenols (dihaloquinones) are themselves capable of inducing formation of oxyferrous DHP B, and an updated catalytic cycle for DHP is proposed. We further demonstrate that, unlike the traditional monofunctional peroxidases, the oxyferrous state in DHP is a peroxidase-competent starting species, which suggests that the ferric oxidation state may not be an obligatory starting point for the enzyme. The data presented herein provide a link between the peroxidase and oxygen transport activities which furthers our understanding of how this bifunctional enzyme is able to unite its two inherent functions in one system.
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Nicoletti FP, Thompson MK, Howes BD, Franzen S, Smulevich G. New Insights into the Role of Distal Histidine Flexibility in Ligand Stabilization of Dehaloperoxidase−Hemoglobin from Amphitrite ornata. Biochemistry 2010; 49:1903-12. [DOI: 10.1021/bi9020567] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Thompson MK, Parnell JM, Franzen S. Block the Inhibitor Binding Site in the Interior of Dehaloperoxidase from Amphitrite Ornata. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.3513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Thompson MK, Vuchkov M, Kahwa IA. Cooperative processes governing formation of small pentanuclear lanthanide(III) nanoclusters and energy transport within and between them. Inorg Chem 2001; 40:4332-41. [PMID: 11487340 DOI: 10.1021/ic0102440] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Syntheses, lanthanide quantitative analyses, mass spectrometry and luminescence spectroscopy, and decay dynamics of crystals containing pentanuclear hetero-lanthanide(III) nanoclusters [(Ln'(5-x)Ln(x))(NO(3))(6)(mu(5)-OH)(mu(4)-L)(2)] (0 < or = x < or = 5), Ln' = Eu or Tb; Ln = La-Nd, Sm-Ho (hereafter Ln'(5-x) Ln(x)) were undertaken in search of information on factors governing self-assembly processes by which the clusters are formed and electronic interactions within and between them. The data obtained are consistent with the self-assembly of Ln'(5-x) Ln(x) nanoclusters being a concerted process featuring a profound expression of complementarity among mutually bridging [Ln(mu(4)-L](-) and [Ln(NO(3))(2)](+) components. The energy transport regime in crystals of Eu(5-x) Ln(x) is in the dynamic regime when x = 0 or Ln = La and, at 293 K, Ln = Dy, despite the presence of two crystallographically different Eu(3+) coordination environments which give rise to a doublet in the excitation and emission spectra of Eu(3+)((5)D(0)). The luminescence decay behavior of Eu(3+)((5)D(0)) in Eu(5-x) Ln(x) (Ln = Dy (for 77 K), Sm) is intermediate between the static and dynamic limits and reveals extensive electronic coupling among lanthanide ions, including many-body processes at relatively high Dy(3+) or Sm(3+) concentrations.
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Nikkhah C, Wright S, Thompson MK, Cheng LH, Adlam DM. Re: Use of specialized bone screws for intermaxillary fixation. Ann Plast Surg 2001; 47:93; author reply 93. [PMID: 11756813 DOI: 10.1097/00000637-200107000-00019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Thompson MK, Tuma RF, Young WF. The effects of pentoxifylline on spinal cord blood flow after experimental spinal cord injury. JOURNAL OF THE ASSOCIATION FOR ACADEMIC MINORITY PHYSICIANS : THE OFFICIAL PUBLICATION OF THE ASSOCIATION FOR ACADEMIC MINORITY PHYSICIANS 2000; 10:23-6. [PMID: 10826005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Previous clinical and experimental investigations have suggested that pentoxifylline, a methylxanthine, can improve cerebrovascular circulation and reduce cerebral edema in cerebrovascular disorders. Pentoxifylline's mechanism of action includes such rheologic effects as enhanced red cell deformability, alterations in leukocyte activation, and modification of coagulation parameters. The purpose of our investigation was to determine the effects of pentoxifylline in an experimental spinal cord injury model. A compression device was used to cause a reproducible spinal cord injury in adult female albino rats. Spinal cord blood flow was monitored using a laser Doppler flow meter pre- and postinjury for 4 hours. The experimental group (N = 7) was injected with pentoxifylline 10 minutes prior to injury. The control group (N = 5) received an identical protocol, except that this group was injected with an equal amount of saline. Results of this investigation revealed that pentoxifylline treatment significantly increased spinal cord blood flow. In the pentoxifylline-treated group, spinal cord blood flow was significantly higher from 120 to 240 minutes postinjury compared with that of the control group. We conclude that via its multiple physiologic effects, pentoxifylline significantly improves spinal cord blood flow in experimental spinal cord injury.
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Thompson MK. Improved medical understanding of human health. PATIENT EDUCATION AND COUNSELING 1997; 31:165-169. [PMID: 9216359 DOI: 10.1016/s0738-3991(97)00992-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The time has come to examine aspects of health and disease on a broader basis than immediate cause and effect. Recognition of the biological processes of adaptation shaped by natural selection has become a requirement for improved understanding of human health in the modern environment, and the time has come for its incorporation into medical teaching and clinical practice.
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Abstract
Disease classes have hitherto been based on anatomical pathology and structural lesions belonging to an earlier ecological medical model involving classification. The diseases of ageing now coming to dominate clinical practice evolve across the clinical threshold in middle age parallel to changes occurring in the internal environment. The concept 'multiple pathology' used to describe the plural features of biological changes now requires new intellectual tools by which to understand overlap phenomena. Boolean algebra and Set Theory are proposed as the relevant enabling concepts, and their application to modern clinical practice is discussed.
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Thompson MK. Re-education via Darwinian medicine. Br J Gen Pract 1995; 45:692-3. [PMID: 8745877 PMCID: PMC1239489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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Thompson MK. General practice at night. And finally, in the good old days.. BMJ (CLINICAL RESEARCH ED.) 1995; 311:1028. [PMID: 7580617 PMCID: PMC2551028 DOI: 10.1136/bmj.311.7011.1028d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Thompson MK. Acute myocardial infarction. Br J Gen Pract 1995; 45:386. [PMID: 7612351 PMCID: PMC1239312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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45
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Thompson MK. Assessment and screening of older people. J R Soc Med 1995; 88:120. [PMID: 7769591 PMCID: PMC1295120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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46
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Thompson MK. General Practice in the Post-Morgagni Era. Med Chir Trans 1992; 85:438-40. [PMID: 1404185 PMCID: PMC1293581 DOI: 10.1177/014107689208500803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Thompson MK. Site for immunising infants. BMJ (CLINICAL RESEARCH ED.) 1992; 304:1178. [PMID: 1392808 PMCID: PMC1882108 DOI: 10.1136/bmj.304.6835.1178-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Thompson MK. Preventive care of elderly people. Br J Gen Pract 1992; 42:216. [PMID: 1389441 PMCID: PMC1372035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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50
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Thompson MK. Randomized controlled trials. Br J Gen Pract 1991; 41:520. [PMID: 1807334 PMCID: PMC1371874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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