Components of Sterol Biosynthesis Assembled on the Oxygen-Avid Hemoglobin of Ascaris
- 18 December 1992
- journal article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 258 (5090) , 1930-1932
- https://doi.org/10.1126/science.1470914
Abstract
The parasitic nematode Ascaris infests a billion people worldwide. Much of its proliferative success is due to prodigious egg production, up to 10(6) sterol-replete eggs per day. Sterol synthesis requires molecular oxygen for squalene epoxidation, yet oxygen is scarce in the intestinal folds the worms inhabit. Ascaris has an oxygen-avid hemoglobin in the perienteric fluid that bathes its reproductive organs. Purified hemoglobin contained tightly bound squalene and functioned as an NADPH-dependent, ferrihemoprotein reductase. All components of the squalene epoxidation reaction--squalene, oxygen, NADPH, and NADPH-dependent reductase--are assembled on the hemoglobin. This molecule may thus function in sterol biosynthesis.Keywords
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