Bioconversion of steroids by the testes of the American lobster, Homarus americanus, in vitro.

Lobster testes have been demonstrated to contain steroid 20-ketone reductase by their capacity to convert [14C]progesterone to 20 alpha-dihydroprogesterone (20 alpha-DHP). The major product was isopolar and identical with 20 alpha-DHP during thin-layer chromatography, high-pressure liquid chromatography, mass spectrometry, and acetate derivative formation. The vas deferens from the lobster was also capable of the same conversions but to a lesser extent. Lobster testes converted [14C]pregnenolone to a major product identified as 20-dihydropregnenolone (20-DHPe) by mass spectrometry after purification by thin-layer chromatography and high-pressure liquid chromatography. The presence of delta 5,3 beta-ol dehydrogenase and delta 5,delta 4-isomerase in the lobster were also indicated. [14C]Cholesterol was not transformed to steroid hormones by lobster testes under the same experimental conditions.