Oestradiol-17 alpha dehydrogenase from chicken liver

Area of Science:

• Biochemistry
• Enzymology

Background:

• Chicken liver contains NADP+-linked oestradiol-17 alpha dehydrogenase (EC 1.1.1.148) and oestradiol-17 beta dehydrogenase (EC 1.1.1.62).
• These enzymes are found in the same subcellular fraction and exhibit similar biochemical properties.

Purpose of the Study:

• To investigate the NADP+-linked oestradiol-17 alpha dehydrogenase from chicken liver.
• To attempt separation of oestradiol-17 alpha dehydrogenase from the closely related oestradiol-17 beta dehydrogenase.

Main Methods:

• Chromatography techniques including CM-cellulose, DEAE-cellulose, dye-ligand chromatography, and affinity chromatography.
• Electrophoresis methods such as slab gel and rod gel electrophoresis, and isoelectric focusing.
• Kinetic studies and substrate specificity analysis.

Main Results:

• Chromatographic behavior on CM-cellulose and DEAE-cellulose was identical for both enzymes, with both activities present in resolved peaks.
• Dye-ligand and affinity chromatography failed to separate the enzymes.
• Electrophoresis revealed multiple bands, with coincident staining for various dehydrogenase activities.
• Isoelectric focusing showed four active peaks, each oxidizing both oestradiol-17 alpha and -17 beta.
• Kinetic studies indicated that the total velocity equaled the sum of separate velocities for mixed substrates.

Conclusions:

• The NADP+-linked oestradiol-17 alpha dehydrogenase and oestradiol-17 beta dehydrogenase activities in chicken liver extracts are difficult to separate using standard biochemical techniques.
• Evidence suggests that a single enzyme may possess both oestradiol-17 alpha and oestradiol-17 beta dehydrogenase activities in chicken liver.
• The enzyme(s) differ significantly from human placental oestradiol-17 beta dehydrogenase based on substrate specificity and inhibitor response.