Over recent decades, diverse intracellular organelles have been recognized as key determinants of Ca(2+) signaling in eukaryotes. In yeast however, information on intra-organellar Ca(2+) concentrations is scarce, despite the demonstrated importance of Ca(2+) signals for this microorganism. Here, we directly monitored free Ca(2+) in the lumen of the endoplasmic reticulum (ER) of yeast cells, usi...

In the calcium-activated photoprotein aequorin, light is produced by the oxidation of coelenterazine, the luciferin used by at least seven marine phyla. However, despite extensive research on photoproteins, there has been no evidence to indicate the origin of coelenterazine within the phylum Cnidaria. Here we report that the hydromedusa Aequorea victoria is unable to produce its own coelenteraz...

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 ca...

Aequorin is a photoprotein which emits blue light on binding, with high affinity (m 10 p~), to calcium (Ca2+) [I]. Aequorin is composed of 189-196 amino-acids, with three EF hand structures, characteristic of Ca2+ bindina sites C2.31. Aeauorin has been used as a-CaZ+ indicator in-a variety of biological systems [l]. The aim of this study was to engineer aequorin in order to measure Ca2+ changes...

Parthenogenetic activation of Lytechinuspictus eggs can be monitored after inje&ion with the Ca-sensitive photoprotein aequorin to estimate calcium release during activation. Parthenogenetic treatments, including the nonelectrolyte urea, hypertonic sea water, and ionophore A23187, all acted to release Ca2+ from intracellular stores. Ionophore and urea solutions release Ca*’ from the same intrac...

Abstract Die Nutzung natürlicher photosynthetischer Enzyme in biohybriden Anwendungen stellt eine attraktive und potenziell nachhaltige Möglichkeit zur Umwandlung von solarer Energie Elektrizität Brennstoffe dar. Jedoch begrenzt die Stabilität photosynthetisch aktiven Proteinen nach der Implementierung biohybride Anwendungsdesigns operative Lebensdauer Biophotoelektroden auf bisher wenige Stund...