Isolation and Characterization of a Ferrihemeprotein Reductase from the Perienteric Fluid of Ascaris Suum
Perdok, Monique M.
Ascaris suum, an intestinal parasite of the pig, has a perienteric hemoglobin with an affinity for oxygen approximately 25,000 times greater than that of human hemoglobin. With such a high oxygen affinity, it does not appear probable that the hemoglobin delivers oxygen to the tissues of the organism at a significant rate. Purification of the hemoglobin revealed an associated factor which was determined to be squalene (Guinn and Goldberg, unpublished data) . Squalene is an intermediate in the cholesterol biosynthetic pathway and requires molecular oxygen and a NADPH-dependent reductase for conversion to squalene epoxide. This led to the proposal that the hemoglobin in A. suum is an enzyme that acts in cholesterol biosynthesis. was purified and a colormetric assay was The hemoglobin employed to investigate its enzymatic characteristics including V mas, K m, temperature optimum, and pH optimum. It was determined that the perienteric hemoglobin A. suum can reduce oxidized cytochrome c (and possibly other ferrihemeproteins) in an NADPH-dependent fashion supporting the working hypothesis that the hemoglobin is an enzyme involved in cholesterol biosynthesis.
iv, 28 p.
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