Electron paramagnetic resonance of spin-labeled aequorin

Marvin D. Kemple, Bruce D. Ray, Gotam K. Jarori, B. D. Nageswara Rao, Franklyn G. Prendergast

Research output: Contribution to journalArticle

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Abstract

Aequorin is a Ca-activated bioluminescent protein from jellyfish. This protein contains two sulfhydryl groups, one of which is essential for its bioluminescence. Little information concerning the structure of and relationship between the metal binding sites of aequorin and the sulfhydryl group(s) is known. Aequorin was modified by attachment of either a maleimide spin-label [studied by electron paramagnetic resonance (EPR)] or the fluorescent label Acrylodan at the essential sulfhydryl in order to gain such information. These modifications caused destabilization of the chromophore of aequorin. Both of the attached labels showed considerable freedom of motion. The spin-label was quite accessible to the solvent, and the fluorescent label was less so. In addition the metal binding properties of the spin-labeled aequorin were studied by Mn(II) EPR. One tight Mn(II) binding site per spin-labeled aequorin was found. The distance between the Mn(II) binding site and the spin-label is at least 20 A. Furthermore, the relative affinity of spin-labeled aequorin for various metal ions was found to be in the order Pr(III) > Mn(II) > Ca(II) > Mg(II).

Original languageEnglish (US)
Pages (from-to)4383-4390
Number of pages8
JournalBiochemistry
Volume23
Issue number19
StatePublished - 1984

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Aequorin
Electron Spin Resonance Spectroscopy
Paramagnetic resonance
Spin Labels
Labels
Metals
Binding Sites
Luminescent Proteins
Bioluminescence
Chromophores
Metal ions
Ions

ASJC Scopus subject areas

  • Biochemistry

Cite this

Kemple, M. D., Ray, B. D., Jarori, G. K., Nageswara Rao, B. D., & Prendergast, F. G. (1984). Electron paramagnetic resonance of spin-labeled aequorin. Biochemistry, 23(19), 4383-4390.

Electron paramagnetic resonance of spin-labeled aequorin. / Kemple, Marvin D.; Ray, Bruce D.; Jarori, Gotam K.; Nageswara Rao, B. D.; Prendergast, Franklyn G.

In: Biochemistry, Vol. 23, No. 19, 1984, p. 4383-4390.

Research output: Contribution to journalArticle

Kemple, MD, Ray, BD, Jarori, GK, Nageswara Rao, BD & Prendergast, FG 1984, 'Electron paramagnetic resonance of spin-labeled aequorin', Biochemistry, vol. 23, no. 19, pp. 4383-4390.
Kemple MD, Ray BD, Jarori GK, Nageswara Rao BD, Prendergast FG. Electron paramagnetic resonance of spin-labeled aequorin. Biochemistry. 1984;23(19):4383-4390.
Kemple, Marvin D. ; Ray, Bruce D. ; Jarori, Gotam K. ; Nageswara Rao, B. D. ; Prendergast, Franklyn G. / Electron paramagnetic resonance of spin-labeled aequorin. In: Biochemistry. 1984 ; Vol. 23, No. 19. pp. 4383-4390.
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AU - Prendergast, Franklyn G.

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AB - Aequorin is a Ca-activated bioluminescent protein from jellyfish. This protein contains two sulfhydryl groups, one of which is essential for its bioluminescence. Little information concerning the structure of and relationship between the metal binding sites of aequorin and the sulfhydryl group(s) is known. Aequorin was modified by attachment of either a maleimide spin-label [studied by electron paramagnetic resonance (EPR)] or the fluorescent label Acrylodan at the essential sulfhydryl in order to gain such information. These modifications caused destabilization of the chromophore of aequorin. Both of the attached labels showed considerable freedom of motion. The spin-label was quite accessible to the solvent, and the fluorescent label was less so. In addition the metal binding properties of the spin-labeled aequorin were studied by Mn(II) EPR. One tight Mn(II) binding site per spin-labeled aequorin was found. The distance between the Mn(II) binding site and the spin-label is at least 20 A. Furthermore, the relative affinity of spin-labeled aequorin for various metal ions was found to be in the order Pr(III) > Mn(II) > Ca(II) > Mg(II).

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