Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.6.1 (sulfatase)
3,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of glutaraldehyde fixation on glucose 6-phosphatase activity in mouse liver was investigated. After transparenchymal perfusion with 2% glutaraldehyde for 1.5 minutes, the activity of the recovered enzyme was higher than those reported for acid phosphatase and aryl sulfatase activities after fixation under similar condition, and an abundant deposition of reaction product was observed in hepatocytes. Subsequent immersion in the same fixative solution for 30 minutes after 4 degrees C resulted in only a slight decrease in the activity. However, the activity was almost completely destroyed after 3 hours of immersion fixation at 4 degrees C following the perfusion. Therefore, the enzyme can be said to be aldehyde-sensitive when a long fixation time is used, but not aldehyde-sensitive during a short fixation time.
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PMID:Sensitivity of glucose 6-phosphatase activity to glutaraldehyde. 16 8

This report describes a radioenzymatic assay for the measurement of salsolinol and dopamine sulfate levels in plasma. It is based on a sulfatase-catalyzed hydrolysis of the sulfoconjugates followed by catechol-O-methyltransferase and [methyl-3H]-S-adenosylmethionine-catalyzed O-methylation of the resulting free salsolinol and dopamine. Rapid thin-layer chromatographic separation of the formed labeled metabolites attributed to the specificity of the differential enzymatic assay of salsolinol and dopamine. This assay was used to study plasma salsolinol and dopamine levels in a group of adult males (n = 36) serving as controls and a group of hospitalized chronic alcoholics (n = 18). The results (mean and range) of this preliminary study show that alcoholics had significantly (p less than 0.0001) elevated plasma concentration of salsolinol sulfate (497; 50-1331 pg/ml) as compared to controls (93; 0-232 pg/ml). This was accompanied by significant (p less than 0.0003) elevation in plasma levels of dopamine sulfate. Elevation of plasma salsolinol sulfate reported here may be interpreted as a reflection of abnormalities in oxidative metabolism of dopamine, metabolically derived acetaldehyde, and/or biological carbonyls in chronic alcoholics.
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PMID:Elevation of plasma salsolinol sulfate in chronic alcoholics as compared to nonalcoholics. 265 49

In sulfatases a Calpha-formylglycine residue is found at a position where their cDNA sequences predict a cysteine residue. In multiple sulfatase deficiency, an inherited lysosomal storage disorder, catalytically inactive sulfatases are synthesized which retain the cysteine residue, indicating that the Calpha-formylglycine residue is required for sulfatase activity. Using in vitro translation in the absence or presence of transport competent microsomes we found that newly synthesized sulfatase polypeptides carry a cysteine residue and that the oxidation of its thiol group to an aldehyde is catalyzed in the endoplasmic reticulum. A linear sequence of 16 residues surrounding the Cys-69 in arylsulfatase A is sufficient to direct the oxidation. This novel protein modification occurs after or at a late stage of cotranslational protein translocation into the endoplasmic reticulum when the polypeptide is not yet folded to its native structure.
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PMID:Conversion of cysteine to formylglycine: a protein modification in the endoplasmic reticulum. 934 45

Human lysosomal arylsulfatase A (ASA) is a prototype member of the sulfatase family. These enzymes require the posttranslational oxidation of the -CH2SH group of a conserved cysteine to an aldehyde, yielding a formylglycine. Without this modification sulfatases are catalytically inactive, as revealed by a lysosomal storage disorder known as multiple sulfatase deficiency. The 2.1 A resolution X-ray crystal structure shows an ASA homooctamer composed of a tetramer of dimers, (alpha 2)4. The alpha/beta fold of the monomer has significant structural analogy to another hydrolytic enzyme, the alkaline phosphatase, and superposition of these two structures shows that the active centers are located in largely identical positions. The functionally essential formylglycine is located in a positively charged pocket and acts as ligand to an octahedrally coordinated metal ion interpreted as Mg2+. The electron density at the formylglycine suggests the presence of a 2-fold disordered aldehyde group with the possible contribution of an aldehyde hydrate, -CH(OH)2, with gem-hydroxyl groups. In the proposed catalytic mechanism, the aldehyde accepts a water molecule to form a hydrate. One of the two hydroxyl groups hydrolyzes the substrate sulfate ester via a transesterification step, resulting in a covalent intermediate. The second hydroxyl serves to eliminate sulfate under inversion of configuration through C-O cleavage and reformation of the aldehyde. This study provides the structural basis for understanding a novel mechanism of ester hydrolysis and explains the functional importance of the unusually modified amino acid.
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PMID:Crystal structure of human arylsulfatase A: the aldehyde function and the metal ion at the active site suggest a novel mechanism for sulfate ester hydrolysis. 952 84

In multiple sulfatase deficiency, a rare human lysosomal storage disorder, all known sulfatases are synthesized as catalytically poorly active polypeptides. Analysis of the latter has shown that they lack a protein modification that was detected in all members of the sulfatase family. This novel protein modification generates a 2-amino-3-oxopropanoic acid (C alpha-formylglycine) residue by oxidation of the thiol group of a cysteine that is conserved among all eukaryotic sulfatases. The oxidation occurs in the endoplasmic reticulum at a stage when the nascent polypeptide is not yet folded. The aldehyde is part of the catalytic site and is likely to act as an aldehyde hydrate. One of the geminal hydroxyl groups accepts the sulfate during sulfate ester cleavage leading to the formation of a covalently sulfated enzyme intermediate. The other hydroxyl is required for the subsequent elimination of the sulfate and regeneration of the aldehyde group. In some prokaryotic members of the sulfatase gene family, the DNA sequence predicts a serine residue, and not a cysteine. Analysis of one of these prokaryotic sulfatases, however, revealed the presence of the C alpha-formylglycine indicating that the aldehyde group is essential for all members of the sulfatase family and that it can be generated from either cysteine or serine.
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PMID:A novel protein modification generating an aldehyde group in sulfatases: its role in catalysis and disease. 969 62

Arylsulfatase A belongs to the sulfatase family whose members carry a Calpha-formylglycine that is post-translationally generated by oxidation of a conserved cysteine or serine residue. The formylglycine acts as an aldehyde hydrate with two geminal hydroxyls being involved in catalysis of sulfate ester cleavage. In arylsulfatase A and N-acetylgalactosamine 4-sulfatase this formylglycine was found to form the active site together with a divalent cation and a number of polar residues, tightly interconnected by a net of hydrogen bonds. Most of these putative active site residues are highly conserved among the eukaryotic and prokaryotic members of the sulfatase family. To analyze their function in binding and cleaving sulfate esters, we substituted a total of nine putative active site residues of human ASA by alanine (Asp29, Asp30, Asp281, Asn282, His125, His229, Lys123, Lys302, and Ser150). In addition the Mg2+-complexing residues (Asp29, Asp30, Asp281, and Asn282) were substituted conservatively by either asparagine or aspartate. In all mutants Vmax was decreased to 1-26% of wild type activity. The Km was more than 10-fold increased in K123A and K302A and up to 5-fold in the other mutants. In all mutants the pH optimum was increased from 4.5 by 0.2-0.8 units. These results indicate that each of the nine residues examined is critical for catalytic activity, Lys123 and Lys302 by binding the substrate and the others by direct (His125 and Asp281) or indirect participation in catalysis. The shift in the pH optimum is explained by two deprotonation steps that have been proposed for sulfate ester cleavage.
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PMID:Amino acid residues forming the active site of arylsulfatase A. Role in catalytic activity and substrate binding. 1021 97

Arylsulfatase A (ASA) belongs to the sulfatase family whose members carry a C(alpha)-formylglycine that is post-translationally generated by oxidation of a conserved cysteine or serine residue. The crystal structures of two arylsulfatases, ASA and ASB, and kinetic studies on ASA mutants led to different proposals for the catalytic mechanism in the hydrolysis of sulfate esters. The structures of two ASA mutants that lack the functional C(alpha)-formylglycine residue 69, in complex with a synthetic substrate, have been determined in order to unravel the reaction mechanism. The crystal structure of the inactive mutant C69A-ASA in complex with p-nitrocatechol sulfate (pNCS) mimics a reaction intermediate during sulfate ester hydrolysis by the active enzyme, without the covalent bond to the key side-chain FGly69. The structure shows that the side-chains of lysine 123, lysine 302, serine 150, histidine 229, the main-chain of the key residue 69 and the divalent cation in the active center are involved in sulfate binding. It is proposed that histidine 229 protonates the leaving alcoholate after hydrolysis.C69S-ASA is able to bind covalently to the substrate and hydrolyze it, but is unable to release the resulting sulfate. Nevertheless, the resulting sulfation is low. The structure of C69S-ASA shows the serine side-chain in a single conformation, turned away from the position a substrate occupies in the complex. This suggests that the double conformation observed in the structure of wild-type ASA is more likely to correspond to a formylglycine hydrate than to a twofold disordered aldehyde oxo group, and accounts for the relative inertness of the C69S-ASA mutant. In the C69S-ASA-pNCS complex, the substrate occupies the same position as in the C69A-ASA-pNCS complex, which corresponds to the non-covalently bonded substrate. Based on the structural data, a detailed mechanism for sulfate ester cleavage is proposed, involving an aldehyde hydrate as the functional group.
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PMID:Crystal structure of an enzyme-substrate complex provides insight into the interaction between human arylsulfatase A and its substrates during catalysis. 1112 5

Cirrhosis is the end stage of many forms of liver pathologies including hepatitis. The liver is known for its vital role in the processing of xenobiotics, including drugs and toxic compounds. Cirrhosis causes changes in the architecture of the liver leading to changes in blood flow, protein binding, and drug metabolizing enzymes. Drug metabolizing enzymes are primarily decreased due to loss of liver tissue. However, not all enzyme activities are reduced and some are only altered in specific cases. There is a great deal of discrepancy between various reports on cytochrome p450 alterations in liver cirrhosis, likely due to differences in disease severity and other underlying conditions. In general, however, CYP1A and CYP3A levels and related enzyme activities are usually reduced and CYP2C, CYP2A, and CYP2B are mostly unaltered. Both alcohol dehyrogenases and aldehyde dehydrogenases are altered in liver cirrhosis, although the etiology of the disease may determine the expression of alcohol dehydrogenases. Glucuronidation is mainly preserved, but there are a number of factors that determine whether glucuronidation is affected in patients with liver cirrhosis. Low sulphation rates are usually found in patients with liver disease but a decrease in sulfatase activity compensates for the decrease in sulphation rates. In all cases, a reduction in drug metabolizing enzyme activities in liver cirrhosis contributes to decreased clearance of drugs seen in patients with liver abnormalities. The reduction in drug metabolizing enzyme activity must be taken into consideration when adjusting doses, especially in patients with severe liver disease.
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PMID:The effect of liver cirrhosis on the regulation and expression of drug metabolizing enzymes. 1507 93

Metabolism of melatonin (MEL) in mouse was evaluated through a metabolomic analysis of urine samples from control and MEL-treated mice. Besides identifying seven known MEL metabolites (6-hydroxymelatonin glucuronide, 6-hydroxymelatonin sulfate, N-acetylserotonin glucuronide, N-acetylserotonin sulfate, 6-hydroxymelatonin, 2-oxomelatonin, 3-hydroxymelatonin), principal components analysis of urinary metabolomes also uncovered seven new MEL metabolites, including MEL glucuronide, cyclic MEL, cyclic N-acetylserotonin glucuronide, cyclic 6-hydroxymelatonin; 5-hydroxyindole-3-acetaldehyde, di-hydroxymelatonin and its glucuronide conjugate. However, N(1)-acetyl-N(2)-formyl-5-methoxy-kynuramine and N(1)-acetyl-5-methoxy-kynuramine, known as MEL antioxidant products, were not detected in mouse urine. Metabolite profiling of MEL further indicated that 6-hydroxymelatonin glucuronide was the most abundant MEL metabolite in mouse urine, which comprised 75, 65, and 88% of the total MEL metabolites in CBA, C57/BL6, and 129Sv mice, respectively. Chemical identity of 6-hydroxymelatonin glucuronide was confirmed by deconjugation reactions using beta-glucuronidase and sulfatase. Compared with wild-type and CYP1A2-humanized mice, Cyp1a2-null mice yielded much less 6-hydroxymelatonin glucuronide (approximately 10%) but more N-acetylserotonin glucuronide (approximately 195%) and MEL glucuronide (approximately 220%) in urine. In summary, MEL metabolism in mouse was recharacterized by using a metabolomic approach, and the MEL metabolic map was extended to include seven known and seven novel pathways. This study also confirmed that 6-hydroxymelatonin glucuronide was the major MEL metabolite in the mouse, and suggested that there was no interspecies difference between humans and mice with regard to CYP1A2-mediated metabolism of MEL, but a significant difference in phase II conjugation, yielding 6-hydroxymelatonin glucuronide in the mouse and 6-hydroxymelatonin sulfate in humans.
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PMID:A metabolomic perspective of melatonin metabolism in the mouse. 1818 45

Type I sulfatases require an unusual co- or post-translational modification for their activity in hydrolyzing sulfate esters. In eukaryotic sulfatases, an active site cysteine residue is oxidized to the aldehyde-containing C(alpha)-formylglycine residue by the formylglycine-generating enzyme (FGE). The machinery responsible for sulfatase activation is poorly understood in prokaryotes. Here we describe the identification of a prokaryotic FGE from Mycobacterium tuberculosis. In addition, we solved the crystal structure of the Streptomyces coelicolor FGE homolog to 2.1 A resolution. The prokaryotic homolog exhibits remarkable structural similarity to human FGE, including the position of catalytic cysteine residues. Both biochemical and structural data indicate the presence of an oxidized cysteine modification in the active site that may be relevant to catalysis. In addition, we generated a mutant M. tuberculosis strain lacking FGE. Although global sulfatase activity was reduced in the mutant, a significant amount of residual sulfatase activity suggests the presence of FGE-independent sulfatases in this organism.
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PMID:Function and structure of a prokaryotic formylglycine-generating enzyme. 1839 May 51


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