Metal ion binding to human hemopexin

Mauk, A. Grant; Mauk, Marcia R.; Lige, Bao; Moore, Geoffrey R.

doi:10.1016/s0162-0134(03)80488-9

Cited by 12 publications

(30 citation statements)

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“…Previously, we reported that the Soret CD spectrum of the human Hx-ferriheme complex exhibits a bisignate line shape that changes in response to the binding of either Zn 2+ or Cu 2+ (17). Prior to our report, however, others reported both bisignate (18) and non-bisignate (19) Soret CD spectra for this complex without comment.…”

mentioning

confidence: 52%

“…Hx-ferriheme concentrations were determined on the basis of a molar absorptivity (280 nm) of 136 000 M -1 cm -1 (17,25). Residue numbers are in accordance with the sequence alignment reported previously (cf.…”

Section: Methodsmentioning

confidence: 78%

“…Following the final stage of purification involving elution over a nickel affinity resin (maximum load 20 mg of Hx-heme per 5 mL of HiTrap Chelating HP (GE Healthcare)), the chromatographic fractions were treated with EDTA (10 mM) to remove trace metal ions (20), and the fractions containing the Hx-heme complex were exchanged into bisTris buffers (pH 6.0 or 7.0, 50 mM bisTris (Sigma), 50 mM NaCl) by centrifugal ultrafiltration (AmiconUltra, 30 000 NMWL Millipore). A single broad band was observed for all Hx-heme fractions by SDS-PAGE under nonreducing conditions (17). With small amounts of protein loaded (<0.5 µg Hx per lane), two overlapping electrophoretic zones with centers that differ in apparent MW by ∼1600 (PageRuler, Fermentas Life Sciences) can be distinguished within the broad electrophoretic band (as analyzed with a ChemiGenius 2 Bio Imaging System and associated software (GeneSap 6.05 for image acquisition and GeneTools 3.06 for data analysis), SynGene) that presumably reflect the heterogeneity of Hx carbohydrate composition (17,(22)(23)(24).…”

Section: Methodsmentioning

confidence: 97%

“…A single broad band was observed for all Hx-heme fractions by SDS-PAGE under nonreducing conditions (17). With small amounts of protein loaded (<0.5 µg Hx per lane), two overlapping electrophoretic zones with centers that differ in apparent MW by ∼1600 (PageRuler, Fermentas Life Sciences) can be distinguished within the broad electrophoretic band (as analyzed with a ChemiGenius 2 Bio Imaging System and associated software (GeneSap 6.05 for image acquisition and GeneTools 3.06 for data analysis), SynGene) that presumably reflect the heterogeneity of Hx carbohydrate composition (17,(22)(23)(24).…”

Section: Methodsmentioning

confidence: 97%

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Chromatographically Distinguishable Heme Insertion Isoforms of Human Hemopexin

2007

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Two spectroscopically distinct, non-interconverting forms of human hemopexin have been isolated by immobilized metal ion affinity chromatography and characterized spectroscopically. Form alpha (characterized by a bisignate Soret CD spectrum) and form beta (Soret CD characterized by a positive Cotton effect) exhibit different spectroscopic responses to addition of Zn2+ or Cu2+, yet both forms exhibit the same metal ion-induced decrease in Tm for the thermally induced release of the heme prosthetic group. Far UV-CD spectra indicate that the two isoforms possess essentially identical secondary structures, but their differential retention during metal ion affinity chromatography indicates slight differences in exposure of His residues on the protein surface. We propose that these observations result from the binding of heme in form beta with an orientation that differs from the crystallographically observed binding orientation for rabbit hemopexin by rotation of the heme prosthetic group by 180 degrees about the alpha-gamma meso-carbon axis and from interaction of metal ions at two separate binding sites.

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mentioning

confidence: 52%

Section: Methodsmentioning

confidence: 78%

Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 97%

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Chromatographically Distinguishable Heme Insertion Isoforms of Human Hemopexin

2007

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“…A similar role might be ascribed to OVOT which was shown to affect calcite crystal morphology at low concentrations [11] and to hemopexin (HPX) which exhibited divalent ions binding properties [42] ( Figure 5). HPX is the 12 th most abundant protein at this stage and these two proteins are overabundant during the primary events of shell mineralisation.…”

Section: Overabundant Proteins During Primary Events Of Shell Mineralmentioning

confidence: 83%

Quantitative proteomics provides new insights into chicken eggshell matrix protein functions during the primary events of mineralisation and the active calcification phase

Marie¹,

Labas

Brionne³

et al. 2015

Journal of Proteomics

146

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Visualization of Metal Ion Buffering via Three-Dimensional Topographic Surfaces (Topos) of Complexometric Titrations

Smith

Hossain

2017

J. Chem. Educ.

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Complexation TOPOS is a free software package to generate 3-D topographic surfaces ("topos") for metal−ligand complexometric titrations in aqueous media. It constructs surfaces by plotting computed equilibrium parameters above a composition grid with "volume of ligand added" as the x-axis and overall system dilution as the y-axis. The sample systems in this paper are restricted to EDTA as a ligand. Other chelating ligands that form exclusively 1:1 complexes could also be modeled with this software. The surfaces show the quality of the equivalence point break under various conditions. More importantly, they develop the phenomenon of metal ion buffering. They clearly distinguish the difference between "pseudobuffering" and "true buffering". They introduce terminology for two different forms of metal ion buffering: (1) mass action metal ion buffering under excess ligand conditions and (2) precipitate metal ion buffering when hydroxide precipitates are present under excess metal ion conditions. Systems modeled are EDTA titrations of Cu 2+ and Mg 2+ . Supporting Information for this paper includes the Complexation TOPOS software, an Excel workbook that generates topos in under 20 seconds. Required inputs are the following: (1) a stability constant for the metal−ligand complex, (2) acid dissociation constants for the ligand, (3) stability constants for hydroxy complexes of the metal, and (4) a K sp value and stoichiometry for hydroxide precipitates. Many constants are tabulated in a workbook tab. Also included are a PowerPoint lecture and teaching materials (for lecture, homework, and prelaboratory activities) that are suitable in general chemistry courses or third-year and graduate courses in analytical chemistry, biochemistry, and geochemistry.

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Metal ion binding to human hemopexin

Cited by 12 publications

References 0 publications

Chromatographically Distinguishable Heme Insertion Isoforms of Human Hemopexin

Chromatographically Distinguishable Heme Insertion Isoforms of Human Hemopexin

Quantitative proteomics provides new insights into chicken eggshell matrix protein functions during the primary events of mineralisation and the active calcification phase

Visualization of Metal Ion Buffering via Three-Dimensional Topographic Surfaces (Topos) of Complexometric Titrations

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