Some Pyridine Nucleotide 



Transhydrogenase Reactions Mediated by 



Estrogenic Steroids 



H. G. Williams-Ashman ^ 



Introduction 



The chemical constitution of the ovarian estrogens is well estab- 

 lished, and the principal l^iocliemical transformations involved in 

 the biosynthesis and metabolism of these steroid hormones have 

 been elucidated (Engel, 1959; Marrian, 1959). A variety of non- 

 steroidal substances also induce estrus in spayed animals, and much 

 empirical information relating molecular architecture to estrogenic 

 activity is available (Huggins, Jensen, and Cleveland, 1954; Dodds, 

 1957). One of the most central problems of female reproductive 

 physiology is now the mechanism of action of estrogens at a molec- 

 ular level. A fruitful approach to this problem has been to study 

 metabolic and enzymatic changes in the uterus following the ad- 

 ministration or deprivation of estrogens (Szego and Roberts, 1953; 

 Mueller, 1957). Such investigations have uncovered many impor- 

 tant biochemical concomitants of estrogen-induced tissue growth 

 which must ultimately be explained by any comprehensive theory 

 of estrogen action. 



This paper will discuss some chemical aspects of the direct stimu- 

 lation of a single isolated enzyme system by estradiol-17;8 and cer- 

 tain other steroidal estrogens. It has been shown that these hor- 



1 From The Ben May Laboratory for Cancer Research and Department of Bio- 

 chemistry, The Unixersity of Chicago, Chicago, lUinois. 



167 



