Proton nuclear magnetic resonance and fluorescence spectroscopic studies of segmental mobility in aequorin and a green fluorescent protein from Aequorea forskalea

Journal Article · Wed Oct 01 00:00:00 EDT 1980 · Biophys. J.; (United States)

OSTI ID:6795785

Nageswara Rao, B D ^[1]; Kemple, M D; Prendergast, F G

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1. Indiana Univ. Purdue Univ., Indianapolis

Aequorin is a protein of low molecular weight (20,000) isolated from the jellyfish Aequorea forskalea which emits blue light upon the binding of Ca/sup 2 +/ ions. This bioluminescence requires neither exogenous oxygen nor any other cofactors. The light emission occurs from an excited state of a chromophore (an imidazolopyrazinone) which is tightly and noncovalently bound to the protein. Apparently the binding of Ca/sup 2 +/ by the protein induces changes in the protein conformation which allow oxygen, already bound or otherwise held by the protein, to react with and therein oxidize the chromophore. The resulting discharged protein remains intact, with the Ca/sup 2 +/ and the chromophore still bound, but is incapable of further luminescence. The fluorescence spectrum of this discharged protein and the bioluminescence spectrum of the original charged aequorin are identical. A green fluorescent protein (GFP) of approx. 30,000 mol wt isolated from the same organism, functions in vivo as an acceptor of energy from aequorin and subsequently emits green light. We are applying proton nuclear magnetic resonance (NMR) spectroscopy and fluorescence spectroscopy to examine structural details of, and fluctuations associated with the luminescent reaction of aequorin and the in vivo energy transfer from aequorin to the GFP.

• OSTI ID: 6795785
• Journal Information: Biophys. J.; (United States), Vol. 32:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PROTEINS
CHEMILUMINESCENCE
ULTRASTRUCTURAL CHANGES
LUMINOSITY
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
CALCIUM IONS
CRUSTACEANS
MOLECULAR STRUCTURE
NMR SPECTRA
OXYGEN
ANIMALS
AQUATIC ORGANISMS
ARTHROPODS
CHARGED PARTICLES
ELEMENTS
INVERTEBRATES
IONS
KINETICS
LUMINESCENCE
MORPHOLOGICAL CHANGES
NONMETALS
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
SPECTRA
550200* - Biochemistry
551000 - Physiological Systems