Partial purification and some properties of rat liver sulfotransferase I, a glucocorticoid sulfotransferase usually restricted to female rats.
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Animals↗
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The steroid alcohol and estrogen sulfotransferases in rodent and human mammary tumors.
Rodent and human mammary tumor systems were investigated to relate the steroid alcohol and estrogen sulfotransferase activities to the hormoanl dependency of the tumor as determined by estrogen receptor content. Unlike the normal mammary gland or the hyperplastic alveolar nodule, rodent mammary neoplasms displayed significant levels of these two sulfotransferases. In the hormone-independent mouse tumors produced from out-growth lines D1, D2, and D8, high dehydroepiandrosterone sulfotransferase activity was characteristic of the rapidity with which hyperplastic alveolar nodules developed into a neoplasms (V-max = 52.8 versus 1.8 fmoles/min/mg protein) while estrone sulfotransferase activity was either not detectable or low (V-max = 5.5 fmoles). After oophorectomy of mice bearing slowly developing tumors, both sulfotransferases in the nonregressing neoplasms showed marked increases in activity (V-max dehydroepiandrosterone = 30.0 fmoles; V-max estrone = 18.5 fmoles). Strain differences not the estrogen receptor content of hormone-dependent rat mammary tumors. In Wistar-Lewis rats the steroid alcohol sulfotransferase activity was at least 35 times higher than in the Sprague-Dawley strain. As was observed in the mouse mammary tumor, Sprague-Dawley rat neoplasms that grew in the absence of ovarian hormones contained significantly greater levels of the steroid alcohol sulfotransferase. Possible correlaion between presence of the steroid alcohol sulfotransferase and the estrogen receptor protein was observed in a limited number of human breast carcinomas.
Alcohols↗
Dehydroepiandrosterone sulfotransferase as a possible shunt for the control of steroid metabolism in human mammary carcinoma.
Human primary mammary tumors were examined to determine what factors were of importance in deciding relative rates of sulfurylation of dehydroepiandrosterone and 17beta-estradiol, such rates having been shown to correlate with the patient's prognosis and response to adrenalectomy (T. L. Dao and P.R. Libby. Enzymic Synthesis of Steroid Sulfate by Mammary Cancer and Its Clinical Implications. Natl. Cancer Inst. Monographs, 34: 205-210, 1971). The sulfurylation of dehydroepiandrosterone and 17beta-estradiol was studied in 41 tumors in vitro using tumor cytosol, adenosine triphosphate, [35S]SO42-, Mg2+, and added steroid. Six tumors showed no sulfurylating ability, 9 sulfurylated dehydroepiandrosterone at a rate greater than that for 17beta-estradiol (ratio, greater than 1), and 26 sulfurylated dehydroepiandrosterone at a rate lower than that for 17beta-estradiol (ratio, less than 1). Evidence was obtained that low levels of dehydroepiandrosterone sulfotransferase were responsible for ratios of less than 1, in many instances. Adenosine 3'-phosphate 5'-phosphosulfate synthesis and steroid sulfotransferase activities were measured in 30 tumors. A significant correlation was found between synthesis of the former and levels of estrogen sulfotransferase, but this relationship did not hold for dehydroepiandrosterone sulfotransferase, again due to low levels of this enzyme in many tumors. It is suggested that dehydroepiandrosterone sulfate formation in the tumors is mainly controlled by the sulfotransferase, which acts as a shunt in regulating the level of free dehydroepiandrosterone, and related compounds, available for metabolism to steroids influencing the growth of mammary epithelial cells.
Adrenalectomy↗
A correlation between estrogen sulfotransferase levels and estrogen receptor status in human primary breast carcinoma.
Estrogen sulfotransferase (EC 2.8.2.4) activity and estrogen receptor levels were measured in 32 human primary breast cancer cytosol preparations. Two types of tumors were identified: type 1, in which estrogen sulfotransferase levels were low (less than 40 pmol 17 beta-estradiol 3-sulfate formed per mg protein per 2 hr) and were independent of [35S]adenosine 3'-phosphate 5'-phosphosulfate production from [35S]sulfate and adenosine triphosphate, and type 2, in which estrogen sulfotransferase levels ranged from 50 to 200 pmol 17 beta-estradiol 3-sulfate per mg protein per 2 hr and were correlated with [35S]adenosine 3'-phosphate 5'-phosphosulfate formation (r = 0.70; p less than 0.005). In type 1 tumors, 11 of 16 were estrogen receptor negative; in type 2 tumors, 2 of 16 were receptor negative. Estrogen sulfotransferase levels in receptor-negative tumors were significantly lower than the levels in receptor-positive tumors (p = 0.025).
Breast Neoplasms↗
3'-phosphoadenylylsulfate:galactosylceramide 3'-sulfotransferase. An optimized assay in homogenates of developing brain.
An optimized in vitro assay of 3'-phosphoadenylysulfate:galactosylceramide 3'-sulfotransferase (EC 2.8.2.11, galactosylceramide sulfotransferase, formerly known as galactocerebroside sulfotransferase) activity is presented, that can be used in crude homogenate of brain tissue of various developmental stages. The enzyme activity is determined by measuring the [35S]sulfatides formed by the enzymic transfer of [35S]sulfate from 3'-phosphoadenoside 5'-phospho [35S]sulfate to galactosylceramides. The sulfatide formation at 30 degrees C is linear up to 30 min and up to a protein concentration of 1 mg per 0.5 ml assay volume. The presence of 0.4% Triton X-100 and 50 micrometer exogenous bovine cerebrosides are optimal for enzyme activity. The pH optimum of the reaction is at pH 6.5 using 0.1 M imidazole buffer. The enzyme reaction is stimulated by NaCl, KCl, MgCl2, CaCl2, MnCl2, ATP and inhibited by ADP. The developmental enzyme activity pattern of mouse brain is the same, if derived from homogenates and microsomes, respectively, under our assay conditions.
Adenosine Diphosphate↗
Purification and characterization of N-hydroxy-2-acetylaminofluorene sulfotransferase from rat liver.
N-Hydroxy-2-acetylaminofluorene (N-OH-2-AAF) sulfotransferase is an enzyme that catalyzes the sulfate transfer from the active sulfate, 3'-phosphoadenosine 5'-phosphosulfate (PAPS), to N-OH-2-AAF to form a highly reactive product acetylaminofluorene N-sulfate. It has been purified about 2000-fold with a yield of over 12% from adult Sprague-Dawley male rat livers by an eight-step procedure. The final preparation was homogeneous on analytrical disc gel electrophoresis. The purified enzyme had activity toward p-nitrophenol with an approximately 1600-fold increase in specific activity over the crude homogenate, but it had almost no detectable activity toward steroids such as estrone, beta-estradiol, testosterone, dehydroisoandrosterone, and corticosterone. There was also very little sulfation activity toward serotonin and L-tyrosine methyl ester. The optimal pH for the enzyme activity is approximately 6.3 when measured in sodium phosphate buffer. Mg2+ at 6 to 9 mM could increase the enzyme activity up to 30%. Mn2+ activated the enzyme only slightly at very low concentrations. Zn2+, Co2+, Cu2+, and Ni2+ were all strongly inhibitory, but Ca2+ had very little effect. Thiol compounds were found to have a stabilizing effect and thiol-blocking reagents were potent inhibitors for this enzyme. The pure enzyme was very unstable especially in diluet solutions. The isoelectric point (pl) of the enzyme is 5.66 +/- 0.07. The molecular weight of the native enzyme was 68,000 +/- 500 as estimated by Sephadex G-100 and G-200 gel filtrations. A single component with molecular weight of 38,250 +/- 1,350 was observed on sodium dodecyl sulfate gel electrophoresis in the absence and presence of 2-mercaptoethanol. Comparison of the enzyme activity in mail and female rat livers at each stage of purification revealed that there was only a trace amount of N-OH-2-AAF sulfotransferase present in the female rat liver.
Animals↗
Dual role of glucuronyl- and sulfotransferases converting xenobiotics into reactive or biologically inactive and easily excretable compounds.
Glucuronyl- and sulfotransferases inactivate a wide variety of hazardous compounds, for example, phenols and dihydrodiols generated during the metabolism of polycyclic hydrocarbons. Our understanding of the firmly membrane-bound glucuronyltransferase is complicated because of their marked activation by membrane perturbants in vitro. Membrane perturbation also occurs in vivo, for example in liver injury caused by CCl4. Moreover, glucuronyltransferases are inducible by xenobiotics. Phenobarbital and 3-methylcholanthrene probably stimulate separate glucuronyltransferases. Sulfotransferases, located in the cytoplasm, often compete with glucuronyltransferases for the same substrates. The generation of 'active sulfate' (PAPS) from cysteine is more likely to be depleted in vivo than the formation of UDP-glucuronic acid generated from carbohydrates. Hence the proportion of sulfate ester/glucuronide may fall with increasing dose of the substrate. Sulfate esters and glucuronides of certain N-hydroxy-arylamines (N-hydroxy-N-acetylaminofluorene, N-hydroxy-phenacetin) are more reactive than the parent compound and bind covalently to cell constituents. Of the two conjugates, sulfate esters are more reactive and thereby more toxic than the corresponding glucuronides. Glucuronides may become toxic in the kidney and bladder where they are highly concentrated.
Animals↗
Studies on bovine adrenal estrogen sulfotransferase. III. Facile synthesis of 3'-phospho- and 2'-phosphoadenosine 5'-phosphosulfate.
A practical synthesis of 3'-phosphoadenosine 5'-phosphosulfate (IV) in yields of 68-72% from adenosine 2',3'-cyclic phosphate 5'-phosphate (II) is described. Reaction of II with triethylamine-N-sulfonic acid affords adenosine 2',3'-cyclic phosphate 5'-phosphosulfate (III) which, on treatment with ribonuclease-T2, provides IV. Spleen phosphodiesterase, on the other hand, converts III to 2'-phosphoadenosine 5'-phosphosulfate (V). The biological activity of IV, measured by sulfate transfer to [6,7-3H2]estrone as mediated by bovine adrenal estrone sulfotransferase (3'-phosphoadenylyl-sulfate:estrone 3-sulfotransferase, EC 2.8.2.4), is identical with that obtained with a sample of IV prepared by an established biochemical procedure. By contrast, V exhibits approximately one-third the activity of the natural isomer.
Adenine Nucleotides↗
Phenol sulfotransferases.
Two phenol sulfotransferases have been purified from rat liver by conventional techniques coupled with affinity chromatography on Affi-Gel blue and ATP-agarose. Both enzymes are homogeneous by the criterion of sodium dodecyl sulfate gel electrophoresis. Each enzyme has a molecular weight of approximately 65,000 and consists of two subunits of apparently equal size. The enzymes are also similar in specificity and in their kinetic parameters but differ in amino acid composition and in their elution from DEAE-cellulose. With adenosine 3'-phosphate 5'-phosphosulfate as donor, a large variety of phenolic compounds serve as sulfate acceptor; sterols, simple alcohols, bile acids, and hydroxamates do not serve as substrates. The transferases may be considered as detoxification enzymes which catalyze the conjugation of xenobiotics containing a phenol group or of phenolic compounds generated by endogenous oxidation. The enzymes act on 3-hydroxyindole to yield indican, suggesting that their in vivo function may include the production of this normal tryptophan metabolite.
Amino Acids↗
Cerebroside sulfotransferase activity in human lung tissues. An elevated level in lung adenocarcinoma.
Cerebroside sulfotransferase activity was demonstrated in particulate fractions from human lung and its carcinoma tissues. The activity in human lung adenocarcinoma was significantly higher than those in a different histological type of carcinoma (squamous cell carcinoma) and in normal tissue from which each carcinoma was derived.
Adenocarcinoma↗
Enzymatic sulfation of steroids. VIII. Control of hepatic cortisol sulfation and glucocorticoid sulfotransferases of rats by the pituitary gland.
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Adrenalectomy↗
The effect of bile duct ligation on hepatic bile acid sulfotransferase activity in the hamster.
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Animals↗
Radioisotopic assay for rat liver sulfotransferase activity.
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Animals↗
Enzymatic sulfation of steroids--VII. Hepatic cortisol sulfation and glucocorticoid sulfotransferases in old and young male rats.
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Aging↗
Glycosaminoglycan sulfotransferases of the developing chick cornea.
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Animals↗
Role of sulfate conjugation in estrogen metabolism and activity.
There has been an increasing interest in the sulfate conjugates of estrogens as important metabolites in steroid hormone homeostasis and activity. In women estrogen sulfates have been known as major components of plasma originating from ovarian secretion and hepatic metabolism. However, only recently has the capacity to sulfurylate estrogens been demonstrated in estrogen target tissues. Porcine uterus estrogen sulfotransferase appears only after the first complete estrous cycle. Following puberty, gilt uterine sulfurylation of estrogens is extremely active during diestrus, whereas estrogen sulfotransferase is not present during estrus. This cycling of estrogen sulfurylation in porcine and human uteri can be related directly to plasma progesterone levels. Rodent and human mammary tumors are also highly active in both steroid alcohol and estrogen sulfotransferases. Unlike uterine sulfotransferases, these enzymes are apparently stimulated by factors that appear following ovariectomy. The function of estrogen sulfurylation by target tissues remains obscure. However, recent investigations have indicated that the cyclic variation in endometrial estrogen sulfurylation may control the availability of 17 beta-estradiol to the cytoplasmic receptor. This premise is supported by the continued high estrogen sulfurylation activity and low nuclear receptor levels during implantation in fertilized gilts and sows. Utilizing purified bovine adrenal sulfotransferase, the substrate and inhibitor requirements were determined for this enzymes. It was also possible to design a specific inhibitor that will block estrogen sulfurylation without interfering with the receptor binding and nuclear migration of physiological levels of 17 beta-estradiol. This inhibitor, 3-methoxy-4-nitroestrone, will help in establishing the role of uterine and mammary estrogen sulfurylation.
Animals↗
Adenosine-5'-phosphosulfate (APS) as sulfate donor for assimilatory sulfate reduction in Rhodospirillum rubrum.
Crude extracts of Rhodospirillum rubrum catalyzed the formation of acid-volatile radioactivity from (35S) sulfate, (35S) adenosine-5'-phosphosulfate, and (35S) 3'-phosphoadenosine-5'-phosphosulfate. An enzyme fraction similar to APS-sulfotransferases from plant sources was purified 228-fold from Rhodospirillum rubrum. It is suggested here that this enzyme is specific for adenosine-5'-phosphosulfate, because the purified enzyme fraction metabolized adenosine-5'-phosphosulfate; 3'-phosphoadenosine-5'-phosphosulfate, however, only at a rate of 1/10 of that with adenosine-5'-phosphosulfate. Further, the reaction with 3'-phosphoadenosine-5'-phosphosulfate was inhibited with 3'-phosphoadenosine-5'-phosphate whereas this nucleotide had no effect on the reaction with adenosine-5'-phosphosulfate. For this activity with adenosine-5'-phosphosulfate the name APS-sulfotransferase is suggested. This APS-sulfotransferase needs thiols for activity; good rates were obtained with either dithioerythritol or reduced glutathione; other thiols like cysteine, 2'-3'-dimercaptopropanol or mercaptoethanol are less effective. The electron donor methylviologen did not catalyze this reaction. The pH-optimum was about 9.0; the apparent Km for adenosine-5'phosphosulfate was determined to be 0.05 mM with this so far purified enzyme fraction. Enzyme activity was increased with K2SO4 and Na2SO4 and was inhibited by 5'-AMP. These properties are similar to assimilatory APS-sulfotransferases from spinach and Chlorella.
Adenine Nucleotides↗