'Respiratory burst' enzyme found

Researchers have identified a key enzyme in the fertilization process of sea urchin eggs, which represent a common model for animal fertilization, according to a study published in the December 7 issue of Developmental Cell.

Working on two species of urchins, Strongylocentrotus purpuratus and Lytechinus variegatus, biologists at Brown University identified a dual oxidase, "Urchin Dual Oxidase" (Udx1), as the enzyme responsible for the typical "respiratory burst" observed at fertilization. During this burst, extracellular oxygen is turned into hydrogen peroxide, which is released into the perivitelline space around the egg.

"This respiratory burst has been a puzzle since the beginning of the century," Victor Vacquier from the Scripps Institution of Oceanography in La Jolla, Calif., who did not participate in the study, told The Scientist. "Then 20 years ago, we realized that the oxygen was actually being used to produce peroxide, but the mechanism still remained unclear."

During fertilization, the ...