Cl. Densmore et al., CHROMATOGRAPHIC RESOLUTION OF THE TYPE-II ESTROGEN-BINDING SITE AND ATYROSINASE-LIKE ENZYMATIC-ACTIVITY FROM RAT UTERINE NUCLEI, Steroids, 59(4), 1994, pp. 282-287
Nuclear extracts from estradiol-treated rat uteri which contain type I
I estrogen binding sites have recently been found to also contain a ty
rosinase-like estradiol metabolizing activity. A recent study suggeste
d that both the binding and enzymatic activities are significantly inc
reased in the presence of micromolar concentrations of copper and asco
rbate, display a number of common biochemical sensitivities, and share
similar ligand/substrate binding affinities. Levels of both activitie
s are significantly increased in uterus in response to hormone (estrog
en) stimulation. These and other similarities indicate a possible rela
tionship between the enzymatic and binding activities, A detailed chro
matographic examination of these two activities in the present study r
evealed that while the type II sites and estradiol metabolizing activi
ty exhibited virtually identical chromatographic properties on DEAE-hi
gh-performance liquid chromatography they are readily resolved on othe
r chromatographic matrices, including phosphocellulose, DNA-cellulose,
and S-Sepharose. These results demonstrate that type II binding sites
are distinct from the tyrosinase-like enzyme activity previously desc
ribed in rat uterine nuclear extracts.