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| 2. |
- Foloppe, N, et al.
(författare)
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Structure, dynamics and electrostatics of the active site of glutaredoxin 3 from Escherichia coli : Comparison with functionally related proteins
- 2001
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 310:2, s. 449-470
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Tidskriftsartikel (refereegranskat)abstract
- The chemistry of active-site cysteine residues is central to the activity of thiol-disulfide oxidoreductases of the thioredoxin superfamily. In these reactions, a nucleophilic thiolate is required, but the associated pK(a), values differ vastly in the superfamily, from less than 4 in DsbA to greater than 7 in Trx. The factors that stabilize this thiolate are, however, not clearly established. The glutaredoxins (Grxs), which are members of this superfamily, contain a Cys-Pro-Tyr-Cys motif in their active site. In reduced Grxs, the pK(a) of the N-terminal active-site nucleophilic cysteine residue is lowered significantly, and the stabilization of the corresponding thiolate is expected to influence the redox potential of these enzymes. Here, we use a combination of long molecular dynamics (MD) simulations, pK(a) calculations, and experimental investigations to derive the structure and dynamics of the reduced active site from Escherichia coli Grx3, and investigate the factors that stabilize the thiolate. Several different MD simulations converged toward a consensus conformation for the active-site cysteine residues (Cys11 and Cys14), after a number of local conformational changes. Key features of the model were tested experimentally by measurement of NMR scalar coupling constants, and determination of pK(a) values of selected residues. The pK(a) values of the Grx3 active-site residues were calculated during the MD simulations, and support the underlying structural model. The structure of Grx3, in combination with the pK(a) calculations, indicate that the pK(a) of the N-terminal active-site cysteine residue in Grx3 is intermediate between that of its counterpart in DsbA and Trx. The pK(a) values in best agreement with experiment are obtained with a low (<4) protein dielectric constant. The calculated pK(a) values fluctuate significantly in response to protein dynamics, which underscores the importance of the details of the underlying structures when calculating pK(a) values. The thiolate of Cys11 is stabilized primarily by direct hydrogen bonding with the amide protons of Tyr13 and Cys14 and the thiol proton of Cys14, rather than by long range interactions from charged groups or from a helix macrodipole. From the comparison of reduced Grx3 with other members of the thioredoxin superfamily, a unifying theme for the structural basis of thiol pK(a) differences in this superfamily begins to emerge.
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| 3. |
- Geschwind, Lars, 1970-, et al.
(författare)
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The Changing Roles of Academic Leaders : Decision-Making, Power, and Performance
- 2019. - 1
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Ingår i: Reforms, Organizational Change and Performance in Higher Education. - Cham : Palgrave Macmillan. - 9783030117382 - 9783030117375 ; , s. 181-210
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Bokkapitel (refereegranskat)abstract
- Major reforms in the Nordic countries have increased the formal autonomy of higher education institutions (HEIs) to make decisions over their own activities, both academic core tasks and managerial/administrative activities. The issue addressed in this chapter is how these changes have affected the role of the academic leader. Across the four countries, we see clear signs of change regarding academic leadership comprising a mix of institutional logics in the interviews: the professional, collegial traditional academic leadership, which is based on rotating systems, election among peers, and collegial decision-making, has been complemented with, and in some places replaced by, a managerial logic with top-down order-giving, performance measurement and appointed managers as a new academic profession. Another related general trend is the greater focus on individual managers. The analysis also shows that Denmark and Finland are the countries that lead the way when it comes to increasing the formal authority of managers. The introduction of appointed managers rather than elected ones has altered the way HEIs operate in these two countries. However, as this chapter has shed light on, management reform has not been implemented in the same depth and with the same pace across and within universities.
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| 4. |
- Kalengayi, Faustine K Nkulu, et al.
(författare)
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'It is a dilemma' : perspectives of nurse practitioners on health screening of newly arrived migrants
- 2015
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Ingår i: Global Health Action. - : Informa UK Limited. - 1654-9716 .- 1654-9880. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Background: Screening newly arrived migrants from countries with high burden of communicable diseases of public health significance is part of the Swedish national strategy against the spread of these diseases. However, little is known about its implementation. Objective: This study aimed at exploring caregivers' experiences in screening newly arrived migrants to generate knowledge that could inform policy and clinical practice. Design: Using an interpretive description framework, we conducted semistructured interviews between November and December 2011 in four Swedish counties, with 15 purposively selected nurses with experience in screening migrants. Data were analyzed using thematic analysis. Results: Participants described a range of challenges including discordant views between migrants and the nurses about medical screening, inconsistencies in rules and practices, and conflicting policies. Participants indicated that sociocultural differences resulted in divergent expectations with migrants viewing the participants as agents of migration authorities. They also expressed concern over being given a new assignment without training and being expected to share responsibilities with staff from other agencies without adequate coordination. Finally, they indicated that existing policies can be confusing and raise ethical issues. All these were compounded by language barriers, making their work environment extremely complex and stressful. Conclusions: These findings illuminate complex challenges that could limit access to, uptake, and delivery of health screening and undermine public health goals, and highlight the need for a multilevel approach. This entails avoiding the conflation of migration with health issues, harmonizing existing policies to make health care services more accessible and acceptable to migrants, and facilitating health professionals' work in promoting public health, improving interagency collaboration and the skills of all staff involved in understanding and effectively responding to migrants' needs, and improving migrants' health literacy through community outreach interventions.
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| 5. |
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| 6. |
- Nordstrand, K, et al.
(författare)
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Direct NMR observation of the Cys-14 thiol proton of reduced Escherichia coli glutaredoxin-3 supports the presence of an active site thiol-thiolate hydrogen bond
- 1999
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 449:2-3, s. 196-200
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Tidskriftsartikel (refereegranskat)abstract
- The active site of Escherichia coli glutaredoxin-3 (Grx3) consists of two redox active cysteine residues in the sequence -C-11-P-Y-C-14-H-. The H-1 NMR resonance of the cysteine thiol proton of Cys-14 in reduced Grx3 is observed at 7.6 ppm. The large downfield shift and NOEs observed with this thiol proton resonance suggest the presence of a hydrogen bond with the Cvs-ll thiolate, which is shown to have an abnormally low pK(a) value. A hydrogen bond would also agree,vith activity data of Grx3 active site mutants. Furthermore, the activity is reduced in a Grx3 H15V mutant, indicating electrostatic contributions to the stabilization of the Cys-ll thiolate, (C) 1999 Federation of European Biochemical Societies.
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| 7. |
- Nordstrand, K, et al.
(författare)
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NMR structure of Escherichia coli glutaredoxin 3-glutathione mixed disulfide complex : Implications for the enzymatic mechanism
- 1999
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 286:2, s. 541-552
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Tidskriftsartikel (refereegranskat)abstract
- Glutaredoxins (Grxs) catalyze reversible oxidation/reduction of protein disulfide groups and glutathione-containing mixed disulfide groups via an active site Grx-glutathione mixed disulfide (Grx-SG) intermediate. The NMR solution structure of the Escherichia coli Grx3 mixed disulfide with glutathione (Grx3-SG) was determined using a C14S mutant which traps this intermediate in the redox reaction. The structure contains a thioredoxin fold, with a well-defined binding site for glutathione which involves two intermolecular backbone-backbone hydrogen bonds forming an antiparallel intermolecular beta-bridge between the protein and glutathione. The solution structure of E. coli Grx3-SG also suggests a binding site for a second glutathione in the reduction of the Grx3-SG intermediate, which is consistent with the specificity of reduction observed in Grxs. Molecular details of the structure in relation to the stability of the intermediate and the activity of Grx3 as a reductant of glutathione mixed disulfide groups are discussed. A comparison of glutathione binding in Grx3-SG and ligand binding in other members of the thioredoxin superfamily is presented, which illustrates the highly conserved intermolecular interactions in this protein family. (C) 1999 Academic Press.
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| 8. |
- Nordstrand, K, et al.
(författare)
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NMR structure of oxidized glutaredoxin 3 from Escherichia coli
- 2000
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 303:3, s. 423-432
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Tidskriftsartikel (refereegranskat)abstract
- A high precision NMR structure of oxidized glutaredoxin 3 [C65Y] from Escherichia coli has been determined. The conformation of the active site including the disulphide bridge is highly similar to those in glutaredoxins from pig liver and T4 phage. A comparison with the previously determined structure of glutaredoxin 3 [C14S, C65Y] in a complex with glutathione reveals conformational changes between the free and substrate-bound form which includes the sidechain of the conserved, active site tyrosine residue. In the oxidized form this tyrosine is solvent exposed, while it adopts less exposed conformation, stabilized by hydrogen bonds, in the mixed disulfide with glutathione. The structures further suggest that the formation of a covalent linkage between glutathione and glutaredoxin 3 is necessary in order to induce these structural changes upon binding of the glutathione peptide. This could explain the observed low affinity of glutaredoxins for S-blocked glutathione analogues, in spite of the fact that glutaredoxins are highly specific reductants of glutathione mixed disulfides.
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