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

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

Research output: Contribution to journalArticle

Abstract

Spectroscopically, the modification of horse heart ferricytochrome c with N-chloro-4-toluolsul-fonamide (Chloramine-T, CT) occurs through a two-step process, the disruption of the methionine-80 sulfur-iron linkage and a reagent-independent change, an intramolecular rearrangement. Chromatographic purification of the preparation at a 2.5:1 reagent-to-protein ratio, pH 8.0-8.5, yields two major products, the FII and FIII CT-cytochromes c. Both products contain modification of only the methionines, 80 and 65, to sulfoxides; both are monomeric, reduced by ascorbate, and the ferrous forms are oxidized by molecular oxygen and bind carbon monoxide. The redox potentials of FII and FIII are 135 and 175±15 mV. The FIII is indistinguishable from the native protein in its binding and the electron donor property toward mammalian cytochrome c oxidase. It also binds nearly as effectively as the native protein to yeast cytochrome c peroxidase, but is a less efficient donor. It is, however, a poor electron acceptor from both mammalian cytochrome c reductase and chicken liver sulfite oxidase. FII lacks cytochrome c oxidase activity and is also a poorer substrate for the other three enzymes. Both the derivatives are consistently better electron donors than acceptors. It is concluded that the binding of cytochrome c to cytochrome c oxidase and to cytochrome c peroxidase does not require the integrity of the methionine-80 sulfur linkage and that the complexation process has a finite degree of freedom with regard to the state of the heme crevice opening. The alterations of the oxidoreduction function have been analyzed in light of both prevailing models of cytochrome c function, the two-site model (one site for oxidizing and the other for reducing enzymes) and the single-site model (the same site for the oxidizing and reducing enzymes). These observations can be accommodated by either model, given the latitude that the binding domains for the oxidizing and the reducing enzymes have finite overlapping and nonoverlapping regions.

Original languageEnglish (US)
Pages (from-to)295-319
Number of pages25
JournalJournal of Protein Chemistry
Volume6
Issue number4
DOIs
StatePublished - Aug 1987

Keywords

  • activity
  • cytochrome c
  • methionines
  • modification
  • redoxpotential

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Methionine-oxidized horse heart cytochromes c. I. Reaction with Chloramine-T, products, and their oxidoreduction properties'. Together they form a unique fingerprint.

  • Cite this

    Pande, J., Kinnally, K., Thallum, K. K., Verma, B. C., Myer, Y. P., Rechsteiner, L., & Bosshard, H. R. (1987). Methionine-oxidized horse heart cytochromes c. I. Reaction with Chloramine-T, products, and their oxidoreduction properties. Journal of Protein Chemistry, 6(4), 295-319. https://doi.org/10.1007/BF00248051