Success in conversion of photoprotein with heat stability
Expansion into fields of reagents for development of pharmaceuticals

Yokohama Research Center (Kanazawa-ku, Yokohama-shi, TEL 045-786-5501), Chisso Corporation (Head office: Chuo-ku, Tokyo, President: Shunichi Okada) has succeeded in converting "Aequorin", a calcium binding photoprotein found in Aequorea victoria (luminescent jellyfish), into "heat-resistant luciferase with fluorescence activity". This is the world's first discovery of conversion of the protein with both "fluorescence activity" and "luminescence activity", and also having "heat stable" properties.

At Yokohama Research Center, research is advanced on gene isolation, purification of recombinant proteins, and applied research of protein groups originating from luminescent organisms such as Aequorea Victoria (luminescent jellyfish), deep sea shrimp, luminescent bacteria, and North American fireflies. Among these, "Aequorin" is the photoprotein which reacts with a small amount of (10^-7M) calcium ion and emits an instant flash of blue light.

This "heat-resistant luciferase with fluorescence activity" indicates properties of photoprotein emitting blue fluorescent light by irradiating a light with wavelength of 350nm. (Refer to picture) Furthermore, by adding a luminescence substrate (luciferin), a standard luciferin-luciferase reaction occurs, and shows continuous luminescent property of luciferase. Moreover, even when this luciferase is heat-treated at 95 degrees for 3 minutes, the fluorescence activity and luciferase luminescence activity remain at 90% or higher.

In luciferases reported up until now, such luciferase with both "fluorescence activity" and "luminescence activity", and also heat stable, is not known. Moreover, under certain conditions, this luciferase can be converted to Aequorin which emits an instant flash of light. In our research laboratory, this discovery was accomplished during the research processes of luminescence and reproduction mechanisms of Aequorin in the photogenic organs of luminescent jellyfish. These results were summarized, a model was proposed, and then published in FEBS Lett.
(2004) 577:105-110.

"Aequorin" is expected to be applied to the analysis of intercellular biological functions using characteristic principles of instant luminescence by calcium ions, the detection of environmental pollutants by antigen-antibody reactions, and other purposes.

Chisso has been selling "Aequorin" for measuring intracellular calcium quantity as a research reagent, and selling Aequorin genes and luminescence substrates to high throughput detection systems for the development of new pharmaceuticals, and also selling modified Aequorin for antigen-antibody reactions.

This "heat-resistant luciferase with fluorescence activity" will be similarly developed as a contributing material to research development in the biochemistry fields.