Dr. Guillermo Mendoza Hernández

menher@laguna.fmedic.unam.mx

Kinetic and structural characterization of enzymes

OBJECTIVES

SUMMARY

17ß-hydroxysteroid dehydrogenase of human placenta cytosol is a dimeric enzyme, comprising two identical subunits with 327 amino acids each and a molecular mass of 34,853. This enzyme has broad specificity and catalyzes the oxido-reduction of estrogens (estradiol-estrone; 16 a -hydroxyestrone-estriol), androgens (dehydroepiandrosterone-androstandiol; testosterone-androstendione) and progesterone and 20 a -hydroxyprogesterone interconversion. Its physiological role is unknown but it is a potential candidate for playing a fundamental role in the regulation of the hormone environment is the maternal-placental-fetal unit. 17ß-estradiol dehydrogenase is so far the only human tissue steroid hormone metabolism enzyme that has been purified to homogeneity in amounts that allow a detailed structural study. Based on alignments, the enzyme has been classified within the short chain alcohol dehydrogenases, a family whose mechanisms and structure we know very little about. We have recently given evidence of conformational changes induced by nucleotide binding, and its denaturation behavior and state of oligomerization in the presence of different agents are now being studied.

PARTICIPANTS

BIBLIOGRAPHY

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