Purification of an inositol 1,4,5-trisphosphate-binding calreticulin-containing intracellular compartment of HL-60 cells

To investigate the identity of Ins(1,4,5)P3-sensitive intracellular Ca2+ stores in myeloid cells, we have developed a method that yields subcellular fractions highly enriched in Ins(1,4,5)P3 binding. HL-60 cells were disrupted by nitrogen cavitation, and subcellular fractions were obtained by differential centrifugation, followed by Percoll- and sucrose-density-gradient separations. A subcellular fraction enriched 26-fold in Ins(1,4,5)P3-binding sites was obtained. This fraction showed no enrichment in plasma-membrane markers and only a comparatively moderate enrichment (7-fold) in endoplasmic-reticulum markers. The ratio between specific enrichment of Ins(1,4,5)P3 binding and endoplasmic-reticulum markers in the different fractions varied over 50-fold, from less than 0.1 to greater than 5. The purified Ins(1,4,5)P3-binding fraction was enriched to a similar extent (27-fold) in the putative intravesicular Ca(2+)-storage protein calreticulin. Our results favour the concept of a distinct Ins(1,4,5)P3-binding, calreticulin-containing compartment (i.e. the calciosome) in HL-60 cells.

Natural killer cell cytolytic granule-associated enzymes. I. Purification, characterization, and analysis of function of an enzyme with sulfatase activity

An enzyme with sulfatase activity has been isolated from the granules of a rat NK leukemia cell line, CRNK-16. The enzyme has been purified from crude preparation, with a specific activity of 52 nmol/min/mg of protein, by DEAE ion exchange and Con A-Sepharose affinity chromatography, resulting in a specific activity of 230 nmol/min/mg of protein. The molecular mass of the purified enzyme was estimated to be 40 kDa by gel filtration chromatography at pH 7.4, but the enzyme had the ability to complex to molecular masses of greater than 300 kDa at low pH when crude granule extract was used as the starting sample, suggesting that it associates with other granule components. The enzyme was determined to be an arylsulfatase by its ability to (a) hydrolyze p-nitrophenyl sulfate (Km = 26.0 mM) and p-nitrocatechol sulfate (pNC sulfate) (Km = 1.1 mM) and (b) be inhibited by sulfite (Ki = 6.0 x 10(-7) M), sulfate (Ki = 1 x 10(-3) M), and phosphate (Ki = 4 x 10(-5) M) in a competitive manner. The pH optimum for enzymatic activity was determined to be 5.6. The role of this enzyme in cytolytic function was investigated by examining the effect of its substrates and inhibitors on granule- and cell-mediated lysis. pNC sulfate was shown to cause a dose-dependent inhibition of target cell lysis by isolated cytolytic granules (complete inhibition at 12.5 mM). Sulfite induced an incomplete inhibition (50% at 1 mM), whereas phosphate was essentially without inhibitory effect. Sulfate, on the other hand, altered lytic activity in a biphasic manner, inasmuch as it induced an inhibition of lysis at high concentrations and an increase of lysis at low concentrations. Cell-mediated lysis was inhibited by pNC sulfate in a dose-dependent fashion at concentrations greater than 2.5 mM, with nearly complete inhibition at 50 mM. Sulfate also altered the lytic activity by intact cells in a biphasic manner, although the effect was much less pronounced. Sulfite and phosphate caused only a 30% inhibition of lytic activity. These results suggest that the sulfatase enzyme is involved in NK cytolytic function, presumably at the lethal hit stage.

Immunoquantification of the low abundance lysosomal enzyme N-acetylgalactosamine 4-sulphatase

The low abundance lysosomal enzyme N-acetylgalactosamine 4-sulphatase (4-sulphatase) has been quantified using a microimmunopurification step and a monoclonal-based ELISA detection system. The assay is similar in principle to a two-site ELISA but uses a single monoclonal antibody against one epitope to bind 4-sulphatase in two separate assay steps. The sensitivity of this assay is sufficient to allow the quantification of 4-sulphatase in human cultured skin fibroblasts derived from normal controls and patients deficient in 4-sulphatase activity (mucopolysaccharidosis type VI or Maroteaux-Lamy syndrome). The results obtained suggest a range of mucopolysaccharidosis type VI or 4-sulphatase deficient mutants, from those expressing little or no quantifiable 4-sulphatase protein to those examples with quantifiable levels of 4-sulphatase protein which is enzymically inactive. Phenotypic variability in patients with a 4-sulphatase deficiency may therefore be partially attributed to a range of protein expressions. The method should allow the determination of 4-sulphatase specific activity in mucopolysaccharidosis type VI patients.

Sanfilippo syndrome, type D: a spectrophotometric assay with prenatal diagnostic potential

Sanfilippo syndrome, type D (MPS IIID), is characterized by moderate physical abnormalities, progressive mental deterioration, and deficient activity of N-acetylglucosamine 6-sulfate sulfatase, a lysosomal hydrolase involved in the degradation of heparin, keratan sulfate, and heparan sulfate. To date, demonstration of the enzyme deficiency typically relies on a radiolabeled trisaccharide substrate derived from heparan sulfate. In our study, we have developed a spectrophotometric assay for the determination of N-acetylglucosamine 6-sulfate sulfatase activity using the monosaccharide, N-acetylglucosamine 6-sulfate, as substrate. The reaction mixture was incubated for 6 h at 37 degrees C and, after Dowex chromatography, released N-acetylglucosamine was measured by a modification of the method of Reissig. Assay conditions were optimized for cultured skin fibroblasts and primary cultures of amniotic fluid cells. The pH optimum for each was 5.5. The assay was linear for 24 h and up to 0.1 absorbance units. Activities of the three known MPS IIID skin fibroblast cell lines were more than 4 SD below the skin fibroblast control mean and more than 5 SD below the control mean for amniotic fluid cells. An enzyme deficiency in cultured amniotic fluid cells of the same magnitude as the skin fibroblasts of the known patients would be detectable and, therefore, prenatal diagnosis by this method is feasible.

Human placental sterylsulfatase: immunocytochemical and biochemical localization

Human placental sterylsulfatase was localised in situ by light and electron microscope immunocytochemical techniques as well as in homogenate and tissue extract fractions by enzyme assays. Light microscope observations on frozen sections of term and preterm placenta revealed sterylsulfatase immunoactivity primarily in the syncytiotrophoblast. Electron microscope observations confirmed the light microscope findings; in addition, they showed that the sulfatase is present in the endoplasmic reticulum of endothelial cells, too. In the syncytiotrophoblast, the enzyme was detectable in the cytoplasmic membrane of the nuclear evelope, in the membranes of the rough endoplasmic reticulum, in the plasma membrane with predominant localisation in coated pits, and in the membranes of endosomes and multivesicular bodies; little or no reactivity was detectable over the membranes of the Golgi complex and of lysosomes. Sterylsulfatase immunoactivity was absent in placentas with hereditary sterylsulfatase deficiency. The observations indicate that human placental sterylsulfatase is normally present in the membranes of compartments along the secretory pathway and the endocytic route of cells lining the fetal and maternal blood. Homogenates of normal term placenta as well as membrane vesicle preparations obtained by extraction of trophoblast tissue with isotonic saline were fractionated by differential centrifugation; the fractions were assayed for specific activities of sterylsulfatase and several marker enzymes of cellular topography. In agreement with our immunocytochemical findings, the results of these biochemical localisation experiments indicate the repeatedly described association of the placental sterylsulfatase with microsomal membranes but also point to the presence of the enzyme's activity in the microvillous plasma membrane of the syncytiotrophoblast. This localisation of sterylsulfatase may have functional implications in the placental uptake of circulating steroid sulfates.

The N-terminal amino-acid sequence of human placental sterylsulfatase

The N-terminus of the recently isolated sterylsulfatase of human placental cellular membranes was sequenced. According to our results, the enzyme preparation proved to be homogeneous at least with respect to this part of the polypeptide chain; the n-terminal sequence of the sulfatase previously proposed by others, however, had to be revised partially.

[Study on the steroid sulfatase (STS) activity in normal individuals and patients with abnormal sexual differentiation]

The STS (steroid sulfatase) gene which has been assigned to the short arm of human X chromosome (band p22) is thought to have escaped from Lyon's inactivation. For that reason, the STS enzyme activities differ between male and female according to the number of X chromosomes in cells. In this report, the STS enzyme activities were studied in different human tissues such as placentas, lymphocytes, and cultured fibroblasts of normal individuals and sex anomaly patients. Tritium labelled dehydroepiandrosterone sulfate (DHA-S) was used as the reaction substrate. The placental STS activities between normal male and female subjects showed a significant difference in spite of wide variances that were ascertained not to be the effects of methodological alterations involving enzyme purification, substrate concentration, and activity calculation (units per mg of protein or DNA). Further, lymphocytes and fibroblasts which had low levels of enzyme concentration compared with placentas, the STS enzyme activities were also significantly different between both sexes. These results confirmed that the STS gene in cells of tissue tested here seemed to be inactive at the gene level and followed the gene dosage effect to some extent. The enzyme activity was also studied in 17 patients with sex anomalies using lymphocytes and cultured fibroblasts. The cells of 45,X Turner Syndrome and of Klinefelter syndrome with 47,XXY or other karyotypes, showed slightly lower levels of enzyme activity when compared with control values of normal males or females. The enzyme activity in intersexual disturbances, especially XX male and XX true hermaphrodites, showed intermediate levels between normal male and female values. This result may give support to the concept that at least one X chromosome in these diseases is genetically abnormal due to X-Y interchanges, something that has been partly proved recently by analysis of H-Y antigen and Y-specific DNA probes. The present study on the STS enzyme activity revealed the presence of a gene dosage effect of STS gene between males and females not precise but rather rough in quantity, and it pointed out problem, some of which were related to genetic and environmental factors modifying the STS gene expression in normal individuals as well as sex anomaly patients.

Immobilized sulfatase:beta-glucuronidase enzymes for the qualitative and quantitative analysis of drug conjugates

The enzymes sulfatase and beta-glucuronidase from Helix pomatia were simultaneously immobilized on aminopropyl control pore glass. Once immobilized, these enzymes retained activity under varied conditions of pH, organic solvent, and temperature. To hydrolyze the sulfate and glucuronide conjugates of xenobiotics, the immobilized enzymes were either added directly to incubation mixtures for qualitative in vitro studies or packed in a short stainless steel column and placed in an HPLC system for quantitative studies. By incorporating specific inhibitors (D-saccharic acid-1,4-lactone to inhibit beta-glucuronidase or phosphate ions to inhibit sulfatase) into the incubation mixture or into the HPLC mobile phases, selective hydrolysis of either sulfate or glucuronide conjugates was achieved. Upon removal of the inhibitors from the incubation mixtures or from the mobile phases, original enzyme activity was restored. The utility of immobilized enzymes was demonstrated for quantitative analysis of sulfate and glucuronide conjugates of fenoldopam, where the liberation of the catechol aglycone moiety was necessary for electrochemical detection.

Sanfilippo D syndrome: estimation of N-acetylglucosamine-6-sulfatase activity with a radiolabeled monosulfated disaccharide substrate

N-Acetylglucosamine-6-sulfatase activity was assayed by incubation of the radiolabeled disaccharide O-(a-N-acetylglucosamine-6-sulfate)-(1----3)-L-[6-3H]-idonic acid (GlcNAc6S-IdOA), with homogenates of leucocytes, cultured fibroblasts, and urine from normal individuals, patients affected with N-acetylglucosamine-6-sulfatase-deficiency (Sanfilippo D syndrome, mucopolysaccharidosis type IIID), and patients affected with other mucopolysaccharidoses and lysosomal storage disorders. The assay clearly distinguished affected homozygotes from their obligate heterozygotes and normal controls and other lysosomal storage disorders. Sulfatase activity in fibroblasts, leucocytes, and urine toward GlcNAc6S-IdOA exhibited a pH optimum at 4.2, 4.5, and 5.1, respectively. Sulfatase activity in fibroblasts had an apparent Km of 7.2 microM and was significantly inhibited by both sulfate and phosphate ions. The action of fibroblast or leucocyte N-acetylglucosamine-6-sulfatase activity toward GlcNAc6S-IdOA is recommended for the routine enzymatic detection and classification of mucopolysaccharidosis type IIID patients.

Enzymatic degradation of urinary indoxyl sulfate by Providencia stuartii and Klebsiella pneumoniae causes the purple urine bag syndrome

The etiology of the purple urine bag syndrome (PUBS), in which the urinary catheter bag of some elderly patients develops intense purple coloration, was studied. The purple was found to be a mixture of indirubin dissolved in the plastic and indigo on its surface. Six patients with PUBS were studied, and Providencia stuartii was isolated from the urine of five and Klebsiella pneumoniae was isolated from the urine of one. These strains produced indigo in 7.9 mM indoxyl sulfate-containing agar. One hundred and fifty isolates of 41 species of bacteria were tested for their ability to produce indigo on agar containing indoxyl sulfate, but only 17 of 27 strains of P. stuartii, a single strain of Klebsiella pneumoniae, and Enterobacter agglomerans were positive. All of the indigo-producing bacteria had an indoxyl phosphatase with a pI of 6.4. This enzyme also possessed indoxyl sulfatase activity and was not present in strains that were unable to produce indigo from indoxyl sulfate. We conclude that PUBS results from the decomposition of urinary indoxyl sulfate to indigo and indirubin by bacteria (notably P. stuartii). As elderly catheterized patients often have high urinary indoxyl sulfate levels and colonization of their urinary tract with P. stuartii, the condition is most commonly seen in them.

The distinction between arylsulphatases in chorionic villi

The relatively high activity of arylsulphatase C (ASC) in the placenta is a potential risk for the misdiagnosis of arylsulphatase A (ASA) or arylsulphatase B (ASB) deficiency in chorionic villus sampling when assayed by synthetic substrates. A clear distinction between these enzymes can be achieved in either the direct villi or the cultured villi cells. Interestingly, the activity of ASC differed significantly in cultured villi cells when prepared by two different methods, namely, minced villi versus treatment with trypsin and collagenase, while ASA and ASB were not affected by these treatments. Whether ASC was directly affected by one of these treatments or whether a selection of cells with different ASC levels was achieved is not yet clear, but this phenomenon clearly indicates the importance of precise definition of CVS preparations to correlate with the enzyme activity data.

Ultrastructural localization of lysosomal enzymes in the egg cortex of Brachydanio

The localization of acid phosphatase (E.C. 3.1.3.2), inorganic trimetaphosphatase (E.C. 3.6.1.2), and aryl sulfatase (E.C. 3.1.6.1) in the cortex of unactivated and activated eggs of Brachydanio was examined by ultrastructural cytochemistry. Using a lead capture method, activity for all three acid hydrolases was demonstrated in organelles of the cortex before and after egg activation. Acid phosphatase (AcPase) reaction product was consistently present in primary lysosomes, secondary lysosomes, multivesicular bodies, and yolk bodies. AcPase activity was absent from mitochondria, profiles of the endoplasmic reticulum, coated pits of exocytosed cortical granules, and coated vesicles. Although most cortical granules of the mature, unactivated egg were unreactive for this enzyme, a few showed AcPase reaction product. It is not clear whether the AcPase-positive granules might be an immature form of cortical granules or a subpopulation of these organelles with lysosomal properties. Most cisternae of the Golgi apparatus did not stain for AcPase; however, reaction product was occasionally localized in a single cisterna as well as several small vesicles at the inner face of the Golgi. The intensity of the reaction product and the pattern of distribution of trimetaphosphatase (Tm-Pase) activity was very similar to that of AcPase. However, TmPase was never observed in cortical granules. Cortices of unactivated and activated eggs showed less overall aryl sulfatase (ArSase) activity when compared with AcPase and TmPase. The presence of ArSase reaction product in lysosomes and multivesicular bodies confirmed the acid hydrolytic nature of these organelles. AcPase and TmPase, and to a lesser extent ArSase, are adequate markers of a cortical lysosomal system in the danio egg.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue-specific expression of human arylsulfatase-C isozymes and steroid sulfatase

Steroid sulfatase (STS; E.C.3.1.6.2), which acts on 3-hydroxysteroid sulfates, and arylsulfatase-C (ARC; E.C.3.1.6.1), assayed with aromatic artificial substrates, are both membrane-bound, microsomal enzymes with alkaline pH optima. Although they copurify during preparation and their gene loci are mapped to the short arm of the human X chromosome where they appear to have escaped from X inactivation, it has not been settled whether STS and ARC are the same enzyme or not. Recent work from our laboratory has shown that ARC exists in two electrophoretically distinct forms in human fibroblasts. We now report that these two forms--the faster migrating (F) and more slowly migrating (S)--occur in human tissues. Each of 11 human tissue types from 10 subjects showed a consistent pattern of ARC isozymes. Thyroid, heart, spleen, skeletal muscle, and adrenal tissue mainly had the S form. In contrast, kidney, liver, and pancreas tissue had mainly the F form, while gonadal, lung, and intestinal tissue had both the S and the F forms. The question of escape of their gene locus from X-chromosome inactivation was examined by comparing the specific activities of ARC and STS in male-derived vis-à-vis female-derived tissues. The majority of the tissues did not show any significant difference in these activities between the sexes, the exceptions being heart muscle, gonadal, and kidney tissue. None showed the 1:2 ratio between male- and female-derived tissues expected of a locus that had escaped X inactivation. The question of identity between ARC and STS was examined by comparing the ratios of their activities in these tissue types: if the enzymes were identical, the ratios of their activities should have remained constant across the different tissue types. It was thus shown that ARC activity varied by as much as 100-fold, depending on the ARC isozymic pattern of the tissue. STS, measured as estrone sulfatase and dehydroepiandrosterone sulfatase, did not show similar variations. This provides further evidence that ARC activity is not necessarily identical to that of STS.

Problems with ultrastructural demonstration of aryl sulphatase activity in rat liver parenchymal cells

The classical method for the electron microscopical demonstration of aryl sulphatase activity in lysosomes (Hopsu-Havu et al. 1967) has been applied for selective demonstration of lysosomes in rat liver parenchymal cells. A positive reaction was obtained in some lysosomes, but the greater part of the precipitate was found in the form of big conglomerates which frequently filled up the interstices between various organelles rather than that they were localized within the organelles. Modifications of the procedure in order to try to confine the demonstration of enzyme activity to lysosomes only included measures: To reduce the amount of primary reaction product, to improve the trapping efficiency of the incubation medium, to prevent possible displacement of the final reaction product. Extralysosomal precipitate persisted under all circumstances; this is interpreted as an artefact rather than as a demonstration of enzyme activity localized in vivo in the cytoplasmic matrix. It is concluded that the present method for demonstration of aryl sulphatase activity is not well suited for microscopical identification of lysosomes in rat liver parenchymal cells.

Studies on cross-reacting material to steroid sulphatase in fibroblasts from patients affected by different types of steroid sulphatase deficiency

Immunologically cross-reacting material to antibodies against steroid sulphatase has not been found in fibroblasts from patients with steroid sulphatase deficiency.

Chromatofocusing of mammalian estrone sulfate sulfohydrolase activity

Estrone sulfate sulfohydrolase (estrogen sulfatase) activity was solubilized by treatment with Triton X-100 from 105,000 g pellets of guinea pig uterus, testis and brain, as well as from rat liver and human placenta. The solubilized forms were subjected to chromatofocusing in the fast protein liquid chromatography (FPLC) system and on conventional columns packed in our laboratory. The guinea pig tissue pattern was complex. Uterus showed peaks of activity with apparent pI's of 9.11 and 7.6; testis contained 3 peaks with pI's of 9.18, 8.7 and 7.5; brain possessed peaks with pI's of 9.28 and 8.6. In each case the major activity peak was that with pI greater than 9. Rat liver activity chromatofocused as a single peak of apparent pI = 6.87 and the human placental enzyme also showed a single, though broad, peak, of pI = 6.57. This suggests not only that the guinea pig enzyme(s) differs markedly from those of rat liver and human placenta, but that there may be qualitative differences between the forms in the three guinea pig tissues. Chromatofocusing behaviour was not independent of the specific exchange resins and ampholytes utilized. The recovered enzyme activity was fairly stable and it seems that chromatofocusing could be a useful step in purification of the guinea pig enzyme(s), particularly the main form possessing a pI greater than 9.

The arylsulphatases of chorionic villi: potential problems in the first-trimester diagnosis of metachromatic leucodystrophy and Maroteaux-Lamy disease

Three pregnancies at risk for late infantile metachromatic leucodystrophy have been monitored using chorionic villus biopsies. In the first of these a false negative diagnosis was made following assay of arylsulphatase A in villi. Subsequent studies have shown that this error was probably due to interference from another sulphatase in the villi, although the possibility that maternal contamination was also partly responsible could not be excluded. For reliable prenatal diagnosis of metachromatic leucodystrophy using chorionic villi it is advisable that studies with the nitrocatechol substrate are carried out on fractionated homogenates, or that the natural substrate is used. Problems may also occur when chorionic villi are used for assay of arylsulphatase B for first trimester diagnosis of Maroteaux-Lamy disease.

Enzyme activity in human gingival crevicular fluid: considerations in data reporting based on analysis of individual crevicular sites

Using a reproducible approach to collection, processing and analysis of gingival crevicular fluid (GCF), this study examined 284 fluid samples from individual crevicular sites for the presence of the enzymes lactate dehydrogenase (LDH), B-glucuronidase (BG) and arylsulfatase (AS). 88 of the sites were from periodontally healthy individuals (probing depth 1-3 mm), while 98 sites from patients with periodontitis were examined before and 2 weeks after scaling and root planing (probing depths 1-3 mm, 4-6 mm and 7-10 mm). This study demonstrated the sensitivity of the enzyme assays. When GCF was collected with a 30-s insertion of the filter strip, 90% of the sites from the control subjects demonstrated LDH activity, 85% demonstrated BG activity and 73% demonstrated AS activity. For the 1-3 mm sites from the patients with periodontitis, 100% of sites from which fluid was collected demonstrated LDH and BG activity, and 90% of sites had AS activity before therapy. After therapy, 100% of sites demonstrated LDH activity, 90% had BG activity and 83% had AS activity. All sites in the 4-6 mm and 7-10 mm categories demonstrated activity of all 3 enzymes. The data were analyzed in terms of enzyme activity/30-s sample and as concentration of enzyme in a standard volume of GCF. Enzyme activity/30-s sample was a different and possibly more sensitive indicator of periodontal pathology than standard clinical parameters. There was a disassociation between clinical parameters and the data for enzyme analysis when it was reported as concentration.

A modified radioimmunoassay for arylsulfatase A in human serum and urine

A radioimmunoassay was developed for the determination of arylsulfatase A (EC 3.1.6.1) in human serum and urine. An isoenzyme of arylsulfatase A purified from human urine was used as a standard antigen. The enzyme was radioiodinated with 125I using the Chloramine T method and was stable for about 4 wk. Antibody-bound enzyme was separated from free enzyme by means of a double antibody technique in the presence of polyethylene glycol (PEG). The working range of the method was 0.15-5.0 ng of arylsulfatase A per assay. The within-assay CV was about 8% for both biological fluids and the between-assay CV for serum was 14.1%. Analytical recoveries were 93.2 +/- 9.1% and 97.8 +/- 5.5% for serum and urine, respectively, and the sensitivity was 0.040 ng of arylsulfatase per assay. Serum samples of 50 healthy blood donors were assayed to establish the normal serum level of immunoreactive enzyme, which was found to be 8.3 ng/ml +/- 1.8 ng/ml of serum. Storage of frozen serum was shown to have no significant effect on results obtained using this RIA.

Sublobular distribution of transferases and hydrolases associated with glucuronide, sulfate and glutathione conjugation in human liver

Activities of glucuronosyltransferase, sulfotransferase, glutathione S-transferase, beta-glucuronidase and sulfatase were determined in microdissected samples of periportal and pericentral sublobular regions from four human livers obtained at immediate autopsy. New methods are presented for the microdetermination of sulfotransferase and sulfatase activities in microdissected samples weighing 0.1 to 4 micrograms dry weight using umbelliferone and 4-methylumbelliferone sulfate as substrates. The three transferases were distributed heterogeneously across the liver lobule. Glucuronosyltransferase and glutathione S-transferase were localized predominantly in pericentral regions. In contrast, sulfotransferase activity was greater in periportal than pericentral regions. Average activities for glucuronosyltransferase and sulfotransferase were 23, and 50 mumoles X gm dry wt-1 X hr-1, respectively, in periportal regions, and 34 and 38 mumoles X gm dry st-1 X hr-1, respectively, in pericentral regions. Activities of glutathione S-transferase were considerably higher than those of the other transferases and were 8.3 mmoles X gm dry wt-1 X hr-1 in periportal areas and 12.2 mmoles X gm dry wt-1 hr-1 in pericentral areas. The two hydrolases studied, beta-glucuronidase and sulfatase, were evenly distributed across the liver lobule. The presence of significant hydrolase and transferase activities in both zones of the liver lobule supports the idea that net production of both sulfate and glucuronide conjugates may be influenced by futile cycling of conjugation-deconjugation reactions in both zones of the liver. Based on enhanced formation of sulfate but not glucuronide conjugates in homogenates of human liver treated with inhibitors of the hydrolases, it is suggested that futile cycling is more pertinent to the regulation of sulfation than glucuronidation.

Isolation of a rat intestinal Clostridium strain producing 5 alpha- and 5 beta-bile salt 3 alpha-sulfatase activity

An unnamed sporeforming microorganism, termed Clostridium sp. strain S2, possessing bile salt sulfatase activity was isolated from rat intestinal microflora. The microorganism was a strictly anaerobic, nonmotile, gram-negative, asaccharolytic, sporeforming rod requiring CO2, vitamin K, and taurine; the guanine-plus-cytosine content of the DNA was 40.8 mol% (Tm), and the strain was tentatively classified as an atypical Clostridium species. Sulfatase activity was specific for 3 alpha-sulfate esters of 5 alpha- and 5 beta-bile salts, leaving the 3 beta-, 7 alpha-, and 12 alpha-sulfates unchanged. Strain S2 also deconjugated tauro- and glyco-conjugated bile salts and partially reduced into the corresponding 6 alpha-hydroxy bile salts. By these reactions, alpha-muricholate and beta-muricholate were more than 80% converted into hyocholate and omega-muricholate, respectively. In addition, strain S2 produced 12 alpha-hydroxysteroid dehydrogenase converting deoxycholate into 3 alpha-hydroxy-12-oxo-5 beta-cholanoate. When strain S2 was associated with gnotobiotic rats, the fecal bile salts were more than 90% desulfated and the fecal excretion of allochenodeoxycholate was five times lower than in control rats.

Recessive X-linked ichthyosis: lack of immunologically detectable steroid sulfatase enzyme protein

Patients with recessive X-linked ichthyosis (RXLI), one hereditary form of scaly skin, lack activity of the enzyme steroid sulfatase in all tissues studied. To investigate the molecular defect underlying the lack of enzyme activity, we prepared antisera against normal enzyme by injecting normal placental microsomal suspensions or partially purified steroid sulfatase into rabbits. Antibody activity was assessed by immunoprecipitation of detergent solubilized steroid sulfatase. In addition, we prepared rabbit antisera against RXLI placental microsomal suspensions. To detect immunologically cross-reactive material in patients' placentas, extracts were studied by immunoblot techniques and by competition with normal enzyme for antibody binding. Patients' extracts did not contain immunoreactive material co-migrating on electrophoresis with purified enzyme nor did they inhibit immunoprecipitation of normal enzyme. Sera from rabbits immunized with RXLI placental microsomes contain no antibodies to normal steroid sulfatase, as judged by their failure to immunoprecipitate normal enzyme or to react with normal steroid sulfatase on immunoblot. Thus the mutation in RXLI appears to reduce steroid sulfatase enzyme protein as well as enzyme activity.