Primary Citation of Related Structures:   1EL4
PubMed Abstract: 
The crystal structure of the photoprotein obelin (22.2 kDa) from Obelia longissima has been determined and refined to 1.7 A resolution. Contrary to the prediction of a peroxide, the noncovalently bound substrate, coelenterazine, has only a single oxygen atom bound at the C2-position ...
The crystal structure of the photoprotein obelin (22.2 kDa) from Obelia longissima has been determined and refined to 1.7 A resolution. Contrary to the prediction of a peroxide, the noncovalently bound substrate, coelenterazine, has only a single oxygen atom bound at the C2-position. The protein-coelenterazine 2-oxy complex observed in the crystals is photo-active because, in the presence of calcium ion, bioluminescence emission within the crystal is observed. This structure represents only the second de novo protein structure determined using the anomalous scattering signal of the sulfur substructure in the crystal. The method used here is theoretically different from that used for crambin in 1981 (4.72 kDa) and represents a significant advancement in protein crystal structure determination.
Related Citations: 
Preparation and preliminary study of crystals of the recombinant calcium-regulated photoprotein obelin from the bioluminescent hydroid obelia longissima Vysotski, E.S., Liu, Z.J., Rose, J., Wang, B.C., Lee, J. (1999) Acta Crystallogr D Biol Crystallogr 55: 1965
Organizational Affiliation: 
Department of Biochemistry and Molecular Biology, University of Georgia, Athens 30602, USA.