Search

The 105 000g supernatant from human placental homogenates, prepared in the presence of sodium taurocholate and Cutscum, contained beta-glucosidase activity towards estrone glucoside as well as towards 4-methylumbelliferyl glucoside (4-MU-glucoside) and glucocerebroside. After partial purification, the estrone glucosidase was found to be active only after the addition of negatively charged phospholipid, whereas the other beta-glucosidases did not exhibit this requirement. The estrone glucosidase was separated from the 4-MU-glucosidase by chromatography on Sephadex G-200 with 0.1% sodium taurocholate in the eluting buffer. The estrone glucosidase was mainly contained in material with a pI of 4.7, while the 4-MU-glucosidase was distributed in fractions with pI values of 4.7 and 6.2 to 6.4. The partially purified estrone glucosidase had a pH optimum of 5.8, as distinct from that of 6.4 found for the 4-MU-glucosidase, and differed markedly from the 4-MU-glucosidase in its response to treatment with heat, sulfhydryl reagents, and detergents. Its sensitivity to changes in pH differed from those reported for glucocerebrosidase.

The cytosol 17 beta-estradiol receptors from rabbit kidney, liver and uterus, compared under identical experimental conditions, were similar in terms of their pH-activity profiles, dependence on incubation temperature, sensitivity to sulfhydryl reagents and steroid specificity. 17 beta-[3H]-Estradiol binding was saturable with all three tissues, having an apparent dissociation constant of 4 X 10(-10)M. The binding of 17 beta-[3H]-estradiol in kidney, liver and uterus was inhibited by estrogens, including estrogen conjugates, but not by testosterone, progesterone or cortisol. The 17 beta-estradiol receptors of liver, kidney and uterus exhibited significant differences with respect to their chromatographic behaviour on heparin-Sepharose. Furthermore, a comparison of their sucrose density gradient centrifugation patterns showed that the 17 beta-[3H]-estradiol-receptor complex of liver and kidney sedimented at 3-4 S in both low and high ionic strength media, while the uterine receptor sedimented at 7-8 S in low ionic strength media and at 4-5 S in high ionic strength media. When the liver and uterine cytosol fractions were combined the uterine receptor was altered and sedimented at 3-4 S in low ionic strength media.

Microsomal preparations from chimpanzee liver can transfer glucose from UDPglucose to the 17alpha-hydroxyl group of 17alpha-estradiol and of 17alpha-estradiol-3-glucuronide. A phenolic glucoside of estrone, but not of either 17alpha- or 17beta-estradiol is also formed. No formation of glucosides of p-nitrophenol, or of diethylstilbestrol was demonstrated. The specificity of glucosyl transfer in the chimpanzee is not identical to that in either the human, the rabbit, or the sheep.

Liver homogenates from mice and from rabbits transfer glucose from UDP-[6-(3)H]glucose, at pH7.0, to oestradiol-17alpha, oestradiol-17beta, oestradiol-17alpha 3-glucuronide, p-nitrophenol and diethylstilboestrol. In the rabbit the phenolic steroids were better substrates than p-nitrophenol for the glucosyltransferase, whereas the reverse was true in the mouse. At pH8.0, rabbit liver, but not mouse liver, transferred glucose to oestradiol-17alpha 3-glucuronide in better yield than that at pH7.0. Evidence is presented for the presence of two glucosyltransferases in rabbit liver. One of these has a pH optimum at about 8.0, and is highly specific for oestradiol-17alpha 3-glucuronide, whereas the other, which has a pH optimum at about 7.0, is similar in this respect to the transferase in mouse liver.

The present study compares the uptake and metabolism of 17 beta-estradiol, 17 beta-estradiol 3-glucoside, and 17 beta-estradiol 3-glucuronide by a highly purified preparation of rabbit liver nuclei. The uptake of the three estrogens was rapid and equilibration was reached within 60 s. The order of uptake was 17 beta-estradiol (64 fmol X mg protein -1) greater than 17 beta-estradiol 3-glucoside (10 fmol X mg protein -1) greater than 17 beta-estradiol 3-glucuronide (6.5 fmol X mg protein -1). Thin-layer chromatography of the estrogens taken up by rabbit liver nuclei indicated the presence of a beta-glucosidase activity associated with the nuclear preparation. The apparent Km value of this enzyme for 17 beta-estradiol 3-glucoside (3.5 microM) was about 10-fold higher when compared with the cytosolic enzyme. The uptake of the three estrogens was linearly proportional to the substrate concentration from 1 to 100 nM. No competition for uptake was observed among the steroids and the presence of diethylstilbestrol did not reduce the uptake of the steroids. These findings suggest that 17 beta-estradiol, 17 beta-estradiol 3-glucoside, and 17 beta-estradiol 3-glucuronide are taken up by nuclei by a nonsaturable diffusion process. The effect of cytosol on the uptake of estrogens by purified nuclei was also investigated. It was observed that cytosol reduced the uptake o 17 beta-estradiol but had little effect on that of its conjugates.

The formation of the 3-glucosides of estrone, 17alpha-estradiol, or 17beta-estradiol by washed rabbit liver microsomes in the absence of UDP glucose (UDPG) was increased by the addition of crude lipid extracts of rabbit or pig liver and of dolichol or retinol. The reaction was stimulated by Mn2+, Mg2+, and Ca2+. Direct transfer of glucose to the steroid from added UDPG also occurred by a mechanism which was inhibited by metal ions. The two transferases can be separated from each other into the 105000 g pellet and supernatant respectively by treatment with detergents.

Although 19-hydroxy-4beta,5-oxido-5beta-androstane-3,17 dione (2a) is converted to estradiol-17beta by human placental microsomes, the incubation of 17beta-hydroxy-4beta,5-oxido-5beta-androstan-3-one (2b) under the same conditions produces only metabolites which are more polar than 17beta-estradiol. The metabolites have been isolated and identified as 3alpha-hydroxy-4beta,5-oxido-5beta-androstan-17-one (4a), 4beta,5-oxido-5beta-androstane-3beta, 17beta-diol (5a) and 4beta,5-oxido-5beta-androstane-3alpha,17beta-diol (6a). These results indicate that functionalization at C-19 is a prerequisite for the biological aromatization of such androgen epoxides.

Multiple forms of the soluble 17 alpha-hydroxysteroid dehydrogenases of female rabbit liver and kidney having similar purification characteristics and isoelectric points were compared with regard to their relative rates of oxidation and reduction of estrogen and androgen substrates, their kinetic parameters and their primary structures. All of the enzyme forms exhibited both 3 alpha- and 17 alpha-enzyme activity toward androgen substrates and the oxidation of the 17 alpha-hydroxysteroid epitestosterone was competitively inhibited by the 3 alpha-hydroxysteroid androsterone. The most basic enzyme forms from liver and kidney had similar relative activities toward estrogen and androgen substrates in the oxidative direction but differed in their activities in the reductive direction. Major differences in the peptide maps of these enzymes were observed. The less basic enzyme forms from the two tissues had similar activities toward estrogen substrates but differed considerably in their relative activities toward androgens. Only minor differences were observed in the peptide maps of these enzymes.

A mammalian hydroxysteroid dehydrogenase having both 3 alpha- and 17 alpha-enzyme activity is described for the first time. Multiple forms of this 3(17) alpha-hydroxysteroid dehydrogenase are present in the cytosol of female rabbit kidney. Four forms of this enzyme were resolved by a purification procedure which included DEAE-cellulose chromatography and isoelectric focusing and three of the isolated enzymes were homogeneous on the basis of polyacrylamide gel electrophoresis. The purified enzymes exhibited 17 alpha-enzyme activity toward both androgen and estrogen substrates and 3 alpha-enzyme activity toward androgens of the 5 alpha-androstane series. In general, the 3 alpha-enzyme activity was greater than the 17 alpha-enzyme activity and the latter activity was greater toward androgens than estrogens. There were differences in substrate specificity among the enzyme forms. In particular, with estrogen substrates one of the forms displayed a high specificity toward 17 alpha-estradiol 3-glucuronide.

Three androgen epoxides, 17beta-hydroxy-4beta,5-oxido-5beta-androstan-3-one (II), 3beta,19-dihydroxy-5,6beta-oxido-5beta-androstan-17-one 3-acetate (VIII), and 19-hydroxy-4beta,5-oxido-5beta-androstane-3,17-dione (V), were synthesized and subsequently evaluated as potential precursors in the biosynthesis of estrogens by incubation with human placental microsomes. One of these epoxides (V) was converted into 17beta-estradiol, whereas the other two were metabolized to unidentified products. The possible intermediacy of an androgen epoxide in the biosynthesis of estrone and of 17beta-estradiol is discussed and a mechanism is proposed for the aromatization process.

Rabbit liver microsomal preparations can transfer xylose from UDP-xylose to estron, 17alpha-estradiol, and 17beta-estradiol, and, in poorer yield, to diethylstilbestrol and p-nitrophenol. No transfer of xylose to estriol, testosterone, epitestosterone or 17alpha-estradiol 3-glucuronide could be demonstrated. The xyloside of [6,7-3H]estrone which was formed by liver microsomes crystallized to constant specific activity with estrone beta-D-xylopyranoside, the chemical preparation of which is described.

Homogenates of liver and kidney tissue from young steers had beta-D-glucosidase (EC 3.2.1.21) activity toward 17alpha-estradiol-3-glucoside, 17beta-estradiol-3-glucoside, 17alpha-estradiol-17-glucoside, and deoxycorticosterone-21-glucoside. The activity towards the phenolic 3-glucosides was largely present in the 100 000 X g supernatant, while that towards 17alpha-estradiol-17-glucoside was concentrated in the microsomes. The use of beef liver preparations for the hydrolysis of steroid 'glucuronide' fractions could result in hydrolysis of other steroid glycosides which might be present.

Two synthetic routes to methyl estra-1,3,5(10)-trien-17 alpha-yl-2'-trifluoroacetamido-3',4',6'-tri-O-acetyl-2'-deoxy-beta-D-glucopyranosid-3-yl-2',3',4'-tri-O-acetyl-beta-D-glucopyranosidyl uronate are described, with the 3-acetyl or the 17 alpha-trifluoroacetyl derivatives of 17 alpha-estradiol as starting materials. Physical characteristics of the fully acetylated double glycoside were determinedmthis compound was converted to sodium estra-1,3,5(10)-trien-17 alpha-yl-2'-acetamido-2'-deoxy-beta-D-glucopyranosid-3-yl-beta-D-glucopyranosid-3-yl-beta-D-glucopyranosidyl uronate, which was found to be identical with the sodium salt of material isolated from rabbit urine.

The continuous infusion of (3)H-6,7-estrone and (3)H-6,7-estradiol has been used to study the metabolic clearance rate (MCR), the interconversions, and the red cell uptake of these steroids in normal males and females. The whole blood MCR of estrone is 1,990 +/- 120 liters per day/m(2) (SE) in males and 1,910 +/- 100 liters per day/m(2) in females. The whole blood MCR of estradiol is 1,600 +/- 80 liters per day/m(2) in males and 1,360 +/- 40 liters per day/m(2) in females. The values in females do not vary significantly when studied in the follicular or luteal phase of the cycle. At least 35% of the total estrone metabolism in both sexes is extrasplanchnic and at least 25% of the total estradiol metabolism in males, and 15% in females is extrasplanchnic. The [rho](BB) (2,1) [transfer constant of estradiol to estrone, which is equivalent to the fraction of the precursor (estradiol) converted to the product (estrone) when both the infusion of the precursor and the measurement of the product are in peripheral blood] is 15%; and the [rho](BB) (1,2) [transfer constant of estrone to estradiol, which is equivalent to the fraction of the precursor (estrone) converted to product (estradiol) when both the infusion of the precusor and the measurement of the product are in peripheral blood] is 5% in both males and females. Our findings concerning the radioactivity in whole blood, as measured by our procedure, were the following: 15-20% of estrone in both sexes and 15% of estradiol in males is associated with red cells. Only 2% of the whole blood radioactivity of estradiol in females is associated with red cells. Changes in the distribution of radioactivity between plasma and red cells will influence the MCR as calculated from plasma, but not as calculated from whole blood.

A white, crystalline compound was obtained from a butanol extract of the urine of rabbits injected subcutaneously with dimethyl sulfoxide. The melting point and infrared spectrum of the compound were identical with those of authentic dimethyl sulfone.