Disruption of the H-bond network in the main access channel of catalase–peroxidase modulates enthalpy and entropy of Fe(III) reduction

Vlasits, Jutta; Bellei, Marzia; Jakopitsch, Christa; Rienzo, Francesca De; Furtmüller, Paul G.; Zámocký, Marcel; Sola, Marcó; Battistuzzi, Gianantonio; Obinger, Christian

doi:10.1016/j.jinorgbio.2010.02.006

Cited by 17 publications

(14 citation statements)

References 77 publications

(162 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence, to a first approximation, the measured E °′ value coincides with Δ H °′ rc,int and would ultimately be determined by the selective enthalpic stabilization of one of the two redox states by first coordination and electrostatic effects. 17,44,47 As a consequence, Δ H °′ rc,int = − nFE °′ corresponds to 10.9 kJ/mol for NdCld and 11.5 kJ/mol for NwCld (Table 3). This approximation clearly suggests that in solution the heme iron environment in the two Clds is very similar.…”

Section: Discussionmentioning

confidence: 99%

Redox Thermodynamics of High-Spin and Low-Spin Forms of Chlorite Dismutases with Diverse Subunit and Oligomeric Structures

et al. 2012

Self Cite

View full text Add to dashboard Cite

Chlorite dismutases (Clds) are heme b-containing oxidoreductases that convert chlorite to chloride and dioxygen. In this work, the thermodynamics of the one-electron reduction of the ferric high-spin forms and of the six-coordinate low-spin cyanide adducts of the enzymes from Nitrobacter winogradskyi (NwCld) and Candidatus “Nitrospira defluvii” (NdCld) were determined through spectroelectrochemical experiments. These proteins belong to two phylogenetically separated lineages that differ in subunit (21.5 and 26 kDa, respectively) and oligomeric (dimeric and pentameric, respectively) structure but exhibit similar chlorite degradation activity. The E°′ values for free and cyanide-bound proteins were determined to be −119 and −397 mV for NwCld and −113 and −404 mV for NdCld, respectively (pH 7.0, 25 °C). Variable-temperature spectroelectrochemical experiments revealed that the oxidized state of both proteins is enthalpically stabilized. Molecular dynamics simulations suggest that changes in the protein structure are negligible, whereas solvent reorganization is mainly responsible for the increase in entropy during the redox reaction. Obtained data are discussed with respect to the known structures of the two Clds and the proposed reaction mechanism.

show abstract

Section: Discussionmentioning

confidence: 99%

Redox Thermodynamics of High-Spin and Low-Spin Forms of Chlorite Dismutases with Diverse Subunit and Oligomeric Structures

et al. 2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…Indeed, the E1 0 values of both variants in 6 M urea are similar to those determined for urea unfolded wt ycc and its K72A/K73A/ K79A mutant, 14 which were shown to possess His/His axial coordination. : 33,74,75,103,126,[128][129][130][131][132][133]135,138,139,145,146,148,149 The intrinsic enthalpic contribution depends on the donor properties of the axial heme ligands, the polarity and the electrostatics at the redox center, whereas the intrinsic entropic term is mainly controlled by oxidation-state dependent differences in the conformational degrees of freedom of the polypeptide chain. [74][75][76][77]98,99,103,126,[128][129][130][131][132][133]135,[137][138][139][144][145][146][147][148][149] For both variants, the E1 0 values increase linearly with increasing temperature with and without urea ( Fig.…”

Section: Voltammetric Responsementioning

confidence: 99%

“…The leastsquare fittings yield slopes of 1.23 and 2.40 and regression coefficients (r 2 ) of 0.999 and 0.995 for the M80A and M80A/ Y67A mutants, respectively. As the changes in DH 0 rc and DS 0 rc arising from the reduction-induced reorganization of the H-bond network at the protein-solvent interface (DH 0 rcðsolvÞ and DS 0 rcðsolvÞ ) are fully compensative, 20,34,74,75,103,104,[130][131][132][133]140,141,[146][147][148][149][150] the absence of perfect compensation (i.e. slopes greater than one) indicates that, beside solvent reorganization effects, protein-based ''intrinsic'' factors significantly contribute to the urea-induced changes in the reduction thermodynamics.…”

Section: Voltammetric Responsementioning

confidence: 99%

Met80 and Tyr67 affect the chemical unfolding of yeast cytochromec: comparing the solutionvs.immobilized state

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…8,18,22,23,[29][30][31][32] Replacement of any of the members of the adduct invariably eliminates catalase activity without appreciably diminishing the peroxidatic capabilities of the enzyme. 30,[32][33][34][35][36][37][38][39] 47 Finally, variants which delete the C-terminal end of LL1 not only eliminate catalase activity as expected, they also produce substantial gains in peroxidatic activity even over other catalase-negative variants (e.g., Y226F), indicating that LL1 may favor catalase over peroxidase activity by also restricting access of electron donors to the heme edge. 36 8 mg/mL) as previously described, 52 except that cultures were not supplemented with δ-aminolevulinic acid or ferrous ammonium sulfate.…”

mentioning

confidence: 86%

A Role for Catalase-Peroxidase Large Loop 2 Revealed by Deletion Mutagenesis: Control of Active Site Water and Ferric Enzyme Reactivity

Kudalkar

Njuma

et al. 2015

Biochemistry

View full text Add to dashboard Cite

Catalase-peroxidases (KatGs), the only catalase-active members of their superfamily, all possess a 35-residue interhelical loop called large loop 2 (LL2). It is essential for catalase activity, but little is known about its contribution to KatG function. LL2 shows weak sequence conservation; however, its length is nearly identical across KatGs, and its apex invariably makes contact with the KatG-unique C-terminal domain. We used site-directed and deletion mutagenesis to interrogate the role of LL2 and its interaction with the C-terminal domain in KatG structure and catalysis. Single and double substitutions of the LL2 apex had little impact on the active site heme [by magnetic circular dichroism or electron paramagnetic resonance (EPR)] and activity (catalase or peroxidase). Conversely, deletion of a single amino acid from the LL2 apex reduced catalase activity by 80%. Deletion of two or more apex amino acids or all of LL2 diminished catalase activity by 300-fold. Peroxide-dependent but not electron donor-dependent kcat/KM values for deletion variant peroxidase activity were reduced 20-200-fold, and kon for cyanide binding diminished by 3 orders of magnitude. EPR spectra for deletion variants were all consistent with an increase in the level of pentacoordinate high-spin heme at the expense of hexacoordinate high-spin states. Together, these data suggest a shift in the distribution of active site waters, altering the reactivity of the ferric state, toward, among other things, compound I formation. These results identify the importance of LL2 length conservation for maintaining an intersubunit interaction that is essential for an active site water distribution that facilitates KatG catalytic activity.

show abstract

Disruption of the H-bond network in the main access channel of catalase–peroxidase modulates enthalpy and entropy of Fe(III) reduction

Cited by 17 publications

References 77 publications

Redox Thermodynamics of High-Spin and Low-Spin Forms of Chlorite Dismutases with Diverse Subunit and Oligomeric Structures

Redox Thermodynamics of High-Spin and Low-Spin Forms of Chlorite Dismutases with Diverse Subunit and Oligomeric Structures

Met80 and Tyr67 affect the chemical unfolding of yeast cytochromec: comparing the solutionvs.immobilized state

A Role for Catalase-Peroxidase Large Loop 2 Revealed by Deletion Mutagenesis: Control of Active Site Water and Ferric Enzyme Reactivity

Contact Info

Product

Resources

About