Lactoperoxidase-catalyzed iodination of horse cytochrome c:monoiodotyrosyl 74 cytochrome c.
Abstract: Iodination of horse cytochrome c with the lactoperoxidase-hydrogen peroxide-iodide system results initially in the formation of the monoiodotyrosyl 74 derivative. This singly modified protein was obtained in pure form by ion exchange chromatography and preparative column electrophoresis. It shows an intact 695 nm absorption band, the midpoint potential of the native protein, a nuclear magnetic resonance spectrum which indicates an undisturbed heme crevice structure, a normal reaction with antibodies directed against native horse cytochrome c, and circular dichroic spectra in which the only changes from those of the native protein can be ascribed to the spectral properties of iodotyrosine itself. This conformationally intact derivative reacts with the succinate-cytochrome c reductase and the cytochrome c oxidase systems of beef mitochondrial particle preparations indistinguishably from the unmodified protein, showing that the region including tyrosine 74 is not involved in these enzymic electron transfer functions of the protein. The circular dichroic spectra of this derivative indicate that the minima observed at 288 and 282 nm in the spectrum of native ferricytochrome c originate from tyrosyl residue 74.
Publication Date: 1977-11-10 PubMed ID: 199598
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- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The research investigates how the iodination of horse cytochrome c with a lactoperoxidase-hydrogen peroxide-iodide system results in the creation of a monoiodotyrosyl 74 variation. This derivative resembles the native protein in its features and reactions, suggesting tyrosine 74 is not directly involved in the enzymic electron transfer functions of the protein.
Research Methodology
- The scientists started by iodinating horse cytochrome c using a lactoperoxidase-hydrogen peroxide-iodide system. This process led to the formation of a single, modified version of the protein known as the monoiodotyrosyl 74 derivative.
- This modified protein was then purified through ion exchange chromatography and preparative column electrophoresis. These processes involve manipulating different charges in the proteins, which allows for the separation of this specific, modified variety from other proteins.
- Once the purified monoiodotyrosyl 74 cytochrome c was obtained, it was analyzed by comparing it to the native protein using various methods like absorption band inspection, nuclear magnetic resonance (NMR) examination, the reaction with antibodies to the native cytochrome c, and circular dichroic spectra analysis.
Findings
- The monoiodotyrosyl 74 cytochrome c was found to be similar to the native protein with respect to several aspects. It demonstrated an intact 695 nm absorption band, a comparable midpoint potential, and a heme crevice structure that remained undisturbed. It also exhibited antibodies’ normal reaction to native Horse Cytochrome c.
- When the altered protein’s reaction with two enzyme systems of beef mitochondrial particle preparations was studied—succinate-cytochrome c reductase and cytochrome c oxidase systems—it behaved indistinguishably from the unaltered protein. This finding implies that tyrosine 74 is not involved in these two enzyme systems’ function of electron transfer in the protein.
- The study of the circular dichroic spectra of the derivative suggested the minima observed at 288 and 282 nm in the spectrum of native ferricytochrome c originates from tyrosyl residue 74.
Implications
- The research findings suggest that the tyrosine 74 region is not associated with the enzymic electron transfer functions of horse cytochrome c. This insight might prove significant in understanding cytochrome c’s molecular structure and function better.
- The iodination method and purification by ion exchange chromatography could also prove valuable in research into other modified proteins.
Cite This Article
APA
Osheroff N, Feinberg BA, Margoliash E, Morrison M.
(1977).
Lactoperoxidase-catalyzed iodination of horse cytochrome c:monoiodotyrosyl 74 cytochrome c.
J Biol Chem, 252(21), 7743-7751.
Publication
Researcher Affiliations
MeSH Terms
- Animals
- Circular Dichroism
- Cytochrome c Group / metabolism
- Electron Transport
- Horses
- Lactoperoxidase
- Monoiodotyrosine
- Myocardium / enzymology
- Peptide Fragments / analysis
- Peroxidases
- Protein Conformation
- Spectrophotometry, Ultraviolet
- Tyrosine
Citations
This article has been cited 2 times.- Sun Q, Yin S, Loo JA, Julian RR. Radical directed dissociation for facile identification of iodotyrosine residues using electrospray ionization mass spectrometry.. Anal Chem 2010 May 1;82(9):3826-33.
- Mason AB, Brown SA. Differential effect of iodination of ovotransferrin and its two half-molecule domains on binding to transferrin receptors on chick embryo red blood cells.. Biochem J 1987 Oct 15;247(2):417-25.
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