Hemerythrin

Stenkamp, Ronald E.

doi:10.1002/0470028637.met150

Cited by 3 publications

(2 citation statements)

References 97 publications

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“…This study provided evidence for nine unique structures upon thermal denaturation. This is somewhat remarkable; it is rare to resolve, let alone characterize, the physical properties of non-native structures. , Here, we extend this approach to investigate the stability of myohemerythrin (Mhr), a ∼14 kDa oxygen binding protein found in marine invertebrates. − The native structure of Mhr is a four helix bundle that coordinates a diiron oxo [Fe(μ-O)Fe] cofactor that can bind oxygen. Over the range of solution temperatures that are studied (15–92 °C), we find evidence for 18 unique structural forms of Mhr, including oxygen-bound and unbound folded states, observed at low temperatures (15 to ∼65 °C); folded and unfolded apoproteins at intermediate temperatures (∼50 to ∼80 °C); apoforms where the folded structure is stabilized by a non-native disulfide bond (∼80 to 92 °C); and folded and unfolded apoproteins with oxidized methionine or cysteine modifications (∼83 to 92 °C).…”

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confidence: 99%

Variable-Temperature ESI-IMS-MS Analysis of Myohemerythrin Reveals Ligand Losses, Unfolding, and a Non-Native Disulfide Bond

et al. 2019

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Variable-temperature electrospray ionization combined with ion mobility spectrometry (IMS) and mass spectrometry (MS) techniques are used to monitor structural transitions of the protein myohemerythrin from peanut worm in aqueous ammonium acetate solutions from ~15 to 92 °C. At physiological temperatures, myohemerythrin favors a four-helix bundle motif and has a diiron oxo cofactor that binds oxygen. As the solution temperature is increased from ~15 to 35 °C, some bound oxygen dissociates; at ~66 °C, the cofactor dissociates to produce populations of both folded and unfolded apoprotein. At higher temperatures (~85 °C and above), the IMS-MS spectrum indicates that the folded apoprotein dominates, and provides evidence for stabilization of the structure by formation of a non-native disulfide bond. In total, we find evidence for 18 unique forms of myohemerythrin as well as information about the structures and stabilities of these states. The high-fidelity of IMS-MS techniques provides a means of examining the stabilities of individual components of complex mixtures that are inaccessible by traditional calorimetric and spectroscopic methods.

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confidence: 99%

Variable-Temperature ESI-IMS-MS Analysis of Myohemerythrin Reveals Ligand Losses, Unfolding, and a Non-Native Disulfide Bond

et al. 2019

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“…The energies of the isolated nn* and nn* transitions were taken to correspond to wavelengths of 230 and 196nm, respectively. The charge distributions of the peptide group in the nn* and nn* excited states were based upon ab initw calculations on formamide (Stenkamp, 1975;Stenkamp & Davidson, 1977).…”

Section: Circular Dichroism Calculationsmentioning

confidence: 99%

CONFORMATIONAL CHARACTERISTICS OF THE N‐ACETYL‐N‘‐METHYLAMIDES OF THE FOUR (LYS, TYR) DIPEPTIDES

Rae

Leach

Minasian

et al. 1981

International Journal of Peptide and Protein Research

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The conformational properties of the N-acetyl-Nhethylamides o f fhe dipeptides I-vsy I-ly sine, ly sy I-ty rosine, ty rosy I-ly sine, and ty rosy I-ty rosine were studied by means of conformational energy calculations, by n.m.r. measurements in deuterated dimethylsulfoxide, and by circular dichroism in water, methanol, dioxane-water, and trifluoroethanol. Since these four dipeptides occur occasionally as bends in proteins, it was o f interest to see whether short-range interactions, acting within the terminally blocked dipeptides, are sufficient to stabilize bend conformations significantly over other conformations. I t was found that the four dipeptides exist as ensembles of conformations in solution.Therefore, it appears that longer-range interactions, such as those present in proteins, are required if bend conformations of these dipeptide sequences are to exist as stable conformations. Three of the dipeptides behave rather similarly.Both the CD and the n.m.r. experiments and computations indicate that the fourth (Lys-Tyr) differs from the others. I t has a preference for compact conformations that appear to be stabilized by strong favorable interactions, primarily hydrogen bonds, between the tyrosyl and the lysyl side chains. The computations suggest that the presence o f these interacfions, and hence the existence of preferred con formations, is strongly solvent-dependent, and that these interactions are weakened in aqueous solution. The work described here forms part of a study Abbreviations: DCHA, dicyclohexylamine; BOC, mi-on the relationship between antigenic butoxycarbonyl; Z, benzyloxycarbonyl; Bzl, benzyl; recognition sites and bends* in proteins and Ac, acetyl; THF, tetrahydrofuran; DMF, N, N-* dimethylformamide; DMSO,dimethylsulfoxide;n.m.r., In the literature, bends are also referred to as chain nuclear magnetic resonance; CD, circular dichroism. reversals, reverse turns, @-turns and @-bends. 0367-8377/81/050575-18 $02.00/0 0 1981 Munksgaard, Copenhagen 575 1.D. RAE ET AL.

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The dual function of flavodiiron proteins: oxygen and/or nitric oxide reductases

et al. 2016

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Flavodiiron proteins have emerged in the last two decades as a newly discovered family of oxygen and/or nitric oxide reductases widespread in the three life domains, and present in both aerobic and anaerobic organisms. Herein we present the main features of these fascinating enzymes, with a particular emphasis on the metal sites, as more appropriate for this special issue in memory of the exceptional bioinorganic scientist R. J. P. Williams who pioneered the notion of (metal) element availability-driven evolution. We also compare the flavodiiron proteins with the other oxygen and nitric oxide reductases known until now, highlighting how throughout evolution Nature arrived at different solutions for similar functions, in some cases adding extra features, such as energy conservation. These enzymes are an example of the (bioinorganic) unpredictable diversity of the living world.

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Hemerythrin

Cited by 3 publications

References 97 publications

Variable-Temperature ESI-IMS-MS Analysis of Myohemerythrin Reveals Ligand Losses, Unfolding, and a Non-Native Disulfide Bond

Variable-Temperature ESI-IMS-MS Analysis of Myohemerythrin Reveals Ligand Losses, Unfolding, and a Non-Native Disulfide Bond

CONFORMATIONAL CHARACTERISTICS OF THE N‐ACETYL‐N‘‐METHYLAMIDES OF THE FOUR (LYS, TYR) DIPEPTIDES

The dual function of flavodiiron proteins: oxygen and/or nitric oxide reductases

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