Determination of the formal reduction potential of Lumbricus terrestris hemoglobin using thin layer spectroelectrochemistry

Dorman, Scott C.; Harrington, John P.; Martin, Melinda S.; Johnson, Timothy V.

doi:10.1016/j.jinorgbio.2003.10.004

Cited by 21 publications

(14 citation statements)

References 19 publications

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“…The observed aromatic residues at the B10 positions in chains a, b and d may be key for the favorable oxidation properties observed in Lumbricus erythrocruorin. 11,12 Additionally, the presence of large aromatic residues at position B10 might lower the NO dioxygenation activity, key for avoiding vasoconstriction that can result from NO scavenging by extracellular hemoglobins. 43…”

Section: Discussionmentioning

confidence: 99%

Crystal Structure of the Hemoglobin Dodecamer from Lumbricus Erythrocruorin: Allosteric Core of Giant Annelid Respiratory Complexes

Strand

Knapp

Bhyravbhatla

et al. 2004

Journal of Molecular Biology

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Section: Discussionmentioning

confidence: 99%

Crystal Structure of the Hemoglobin Dodecamer from Lumbricus Erythrocruorin: Allosteric Core of Giant Annelid Respiratory Complexes

Strand

Knapp

Bhyravbhatla

et al. 2004

Journal of Molecular Biology

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“…Determination of the formal reduction potentials (E ') for each acellular hemoglobin was carried out using a modified, optically transparent thinlayer electrochemical cell based upon the design of Faulkner and coworkers [21][22][23]. Although heme proteins can react directly with the surfaces of the electrodes, the reaction is typically slow and often irreversible.…”

Section: Redox Potential Determined By Spectroelectrochemical Analysismentioning

confidence: 99%

Acellular Invertebrate Hemoglobins as Model Therapeutic Oxygen Carriers: Unique Redox Potentials

Harrington

Kobayashi

Dorman

et al. 2007

Artificial Cells, Blood Substitutes, and Biotechnology

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Natural acellular polymeric hemoglobins (Hb) provide oxygen transport and delivery within many terrestrial and marine invertebrate organisms. It has been our premise that these natural acellular Hbs may serve as models of therapeutic hemoglobin-based oxygen carriers (HBOC). Our attention has focused on the acellular Hb from the terrestrial invertebrate, Lumbricus terrestris (Lt), which possesses a unique hierarchical structure and a unique ability to function extracellularly without oxidative damage. Lumbricus Hb and Arenicola Hb are resistant to autoxidation, chemical oxidation by potassium ferricyanide, and have little or no capacity to transfer electrons to Fe(+3)-complexes at 37 degrees C. An understanding of how these invertebrate acellular oxygen carriers maintain their structural integrity and redox stability in vivo is vital for the design of a safe and effective red cell substitute. We report here a positive redox potential for these giant hemoglobins that may lie at the basis for its resistance to oxidation.

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“…The Hb found in Lumbricus terrestris (earthworm) has a midpoint potential of +73 mV (52). The bacterial single domain globin Vgb found in Vitreoscilla purifies as a dimer, its two hemes having potentials of +118 and −122 mV (53).…”

Section: Functions Of Ctb and Other Trhbsmentioning

confidence: 99%

Purification and Spectroscopic Characterization of Ctb, a Group III Truncated Hemoglobin Implicated in Oxygen Metabolism in the Food-Borne Pathogen Campylobacter jejuni

et al. 2006

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Campylobacter jejuni is a foodborne bacterial pathogen that possesses two distinct hemoglobins, encoded by the ctb and cgb genes. The former codes for a truncated hemoglobin (Ctb) in group III, an assemblage of uncharacterized globins in diverse clinically-and technologically-significant bacteria. Here, we show that Ctb purifies as a monomeric, predominantly oxygenated species. Optical spectra of ferric, ferrous, O 2 -and CO-bound forms resemble those of other hemoglobins. However, resonance Raman analysis shows Ctb to have an atypical ν Fe-CO stretching mode at 514 cm -1 , compared to the other truncated hemoglobins that have been characterized so far. This implies unique roles in ligand stabilisation for TyrB10, HisE7 and TrpG8, residues highly conserved within group III truncated hemoglobins. Since C. jejuni is a microaerophile, and a ctb mutant exhibits O 2 -dependent growth defects, one of the hypothesised roles of Ctb is in the detoxification, sequestration or transfer of O 2 The midpoint potential (E h ) of Ctb was found to be −33 mV, but no evidence was obtained in vitro to support the hypothesis that Ctb is reducible by NADH or NADPH. This truncated hemoglobin may function in the facilitation of O 2 transfer to one of the terminal oxidases of C. jejuni or instead facilitate O 2 transfer to Cgb for NO detoxification.In the past three decades, our understanding of hemoglobins has grown to recognise new classes of proteins in addition to the classical vertebrate α-and β-globins, myoglobin and the symbiotic Hbs of leguminous plants. These 'new' globins -some of which may actually be amongst the oldest, or ancestral, globins in a phylogenetic context (1) -include the non-symbiotic plant Hbs, chimeric flavohemoglobins, and the trHbs. Globins may be classified functionally -into those that detoxify NO and those that are involved in O 2 transfer or detoxification -or structurally into three categories (2). The first structural category contains flavoHbs that possess a C-terminal ferredoxin-NADP + reductase-like domain and an N-terminal globin domain; bacterial (3,4) and yeast (5) examples function in the enzymic removal of NO to produce nitrate (6,7). The second category contains single domain Hbs that are very similar to the N-terminal domain of the flavoHbs; however, their functions appear more varied than those of the flavoHbs. As an example, Vgb, found in the obligate aerobe Vitreoscilla, is believed to function in the facilitation of O 2 transfer to cytochrome bo' (8), whereas the C.

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Determination of the formal reduction potential of Lumbricus terrestris hemoglobin using thin layer spectroelectrochemistry

Cited by 21 publications

References 19 publications

Crystal Structure of the Hemoglobin Dodecamer from Lumbricus Erythrocruorin: Allosteric Core of Giant Annelid Respiratory Complexes

Crystal Structure of the Hemoglobin Dodecamer from Lumbricus Erythrocruorin: Allosteric Core of Giant Annelid Respiratory Complexes

Acellular Invertebrate Hemoglobins as Model Therapeutic Oxygen Carriers: Unique Redox Potentials

Purification and Spectroscopic Characterization of Ctb, a Group III Truncated Hemoglobin Implicated in Oxygen Metabolism in the Food-Borne Pathogen Campylobacter jejuni

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