Methionine-oxidized horse heart cytochromes c. I. Reaction with Chloramine-T, products, and their oxidoreduction properties

Pande, Jayanti; Kinnally, Kathleen W.; Thallum, K.K.; Verma, Balbir Chand; Myer, Yash P.; Rechsteiner, Lucia; Bosshard, Hans Rudolf

doi:10.1007/bf00248051

Cited by 17 publications

(41 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These values fit within the range between 100 and 205 mV reported for the horse heart Met-SO derivative. 5,12,16,17 The drop in the potential compared to that of WT* (274±4 mV) 21 is consistent with the change in ligation and a more solvent-accessible heme pocket. The differences in the potentials of WT-M80SO and Lys-ligated M80K # (−94±2 mV) 21 are in accord with Met-SO, rather than Lys, being the sixth ligand in the ferrous protein.…”

Section: Resultsmentioning

confidence: 63%

“…While some assays of cyt c oxidase activity have found minimal differences between the native and Met-SO cyt c , 5,16 others suggested that ET from cyt c to cyt c oxidase is impaired by the modification. 3 Multiple studies have found that succinate-cyt c reductase activity is greatly reduced upon Met80 oxidation, 5,16,17 but there have also been reports of no effects on this redox reaction. 18 The reduction potentials and ET rates with a common reductant sodium ascorbate have also differed from one study to another.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ligation and Reactivity of Methionine-Oxidized Cytochrome c

Zhong

Pletneva

2018

Inorg. Chem.

View full text Add to dashboard Cite

Met80, one of the heme iron ligands in cytochrome c (cyt c) is readily oxidized to Met sulfoxide (Met-SO) by several biologically-relevant oxidants. The modification has been suggested to impact both the electron-transfer (ET) and apoptotic functions of this metalloprotein. The coordination of the heme iron in Met-oxidized cyt c (Met-SO cyt c) is critical for both of these functions but has remained poorly defined. We present electronic absorption, NMR, and EPR spectroscopic investigations as well kinetic studies and mutational analyses to identify the heme iron ligands in yeast iso-1 Met-SO cyt c. Similar to the alkaline form of native cyt c, Lys73 and Lys79 ligate to the ferric heme iron in the Met80-oxidized protein but this coordination takes place at much lower pH. The ferrous heme iron is ligated by Met-SO implying the redox-linked ligand switch in the modified protein. Binding studies with a model peptide microperoxidase-8 provide a rationale for alterations in ligation and for the role of the polypeptide packing in native and Met-SO cyt c. Imidazole binding experiments have revealed that Lys dissociation from the ferric heme in K73A/K79G/M80K (M80K#) and Met-SO is more than three orders of magnitude slower than the opening of the heme pocket that limits Met80 replacement in native cyt c. The Lys-to-Met-SO ligand substitution gates ET of ferric Met-SO cyt c with Co(terpy)22+. Owing to the slow Lys dissociation step, ET reaction is slow but possible, which is not the case for non-switchable M80A and M80K#. Acidic conditions cause Lys replacement by a water ligand in Met-SO cyt c (pKa=6.3±0.1) increasing intrinsic peroxidase activity of the protein. This pH-driven ligand switch may be a mechanism to boost peroxidase function of cyt c specifically in apoptotic cells.

show abstract

Section: Resultsmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Ligation and Reactivity of Methionine-Oxidized Cytochrome c

Zhong

Pletneva

2018

Inorg. Chem.

View full text Add to dashboard Cite

show abstract

“…Furthermore, our results with the fluorescent analog ([ald]SS-20) indicate that SS-20, when interacting with CL, can penetrate into the heme environment of cyt c and protect the Met 80 -Fe ligation. This is further supported by circular dichroism studies showing that SS-20 protects the negative Cotton peak of cyt c against CL-induced damage, thus preserving the stability of the Fe-Met 80 coordination and π-π interaction within the heme environment [44]. When administered to rats prior to onset of ischemia, SS-20 significantly protected coupled respiration in ischemic mitochondria studied ex vivo , including O 2 consumption initiated by direct reduction of cyt c with TMPD.…”

Section: Discussionmentioning

confidence: 73%

Disruption of cytochrome c heme coordination is responsible for mitochondrial injury during ischemia

Birk

Chao

Liu

et al. 2015

Biochimica et Biophysica Acta (BBA) - Bioenergetics

View full text Add to dashboard Cite

Background It was recently suggested that electron flow into cyt c, coupled with ROS generation, oxidizes cyt c Met80 to Met80 sulfoxide (Met-O) in isolated hearts after ischemia-reperfusion, and converts cyt c to a peroxidase. We hypothesize that ischemia disrupts Met80-Fe ligation of cyt c, forming pentacoordinated heme Fe2+, which inhibits electron transport (ET) and promotes oxygenase activity. Methods SS-20 (Phe-D-Arg-Phe-Lys-NH2) was used to demonstrate the role of Met80-Fe ligation in ischemia. Mitochondria were isolated from ischemic rat kidneys to determine sites of respiratory inhibition. Mitochondrial cyt c and cyt c Met-O were quantified by western blot, and cristae architecture was examined by electron microscopy. Results Biochemical and structural studies showed that SS-20 selectively targets cardiolipin (CL) and protects Met80-Fe ligation in cyt c. Ischemic mitochondria showed 17-fold increase in Met-O cyt c, and dramatic cristaeolysis. Loss of cyt c was associated with proteolytic degradation of OPA1. Ischemia significantly inhibited ET initiated by direct reduction of cyt c and coupled respiration. All changes were prevented by SS-20. Conclusion Our results show that ischemia disrupts the Met80-Fe ligation of cyt c resulting in formation of a globin-like pentacoordinated heme Fe2+ that inhibits ET, and converts cyt c into an oxygenase to cause CL peroxidation and proteolytic degradation of OPA1, resulting in cyt c release. General significance Cyt c heme structure represents a novel target for minimizing ischemic injury. SS-20, which we show to selectively target CL and protect the Met80-Fe ligation, minimizes ischemic injury and promotes ATP recovery.

show abstract

“…Chloramine-T was employed as a selective reagent for oxidizing the Met80 residue of Cyt-c, according to previous reports. 42 , 43 The product obtained was designated as ex situ generated SO-Cyt. For this purpose, 100 μL of 1 mM Cyt-c were mixed with 100 μL of 5 mM chloramine-T and the pH was adjusted to 8.4.…”

Section: Methodsmentioning

confidence: 99%