Enzymes arylsulfatase

Outline the design of a histochemical procedure for the localization of the enzyme arylsulfatase in tissues the enzyme catalyzes the following reaction type ... 

Aryplase is a specific form of the recombinant human enzyme, arylsulfatase B. In a phase I trial, the enzyme was well tolerated, and there were no drug-related serious adverse events and no significant allergic reactions to the infusions. Urinary GAG excretion was reduced by a mean of 70%in the high dose group and 55% in the low dose group. Urinary GAj excretion is a biomarker for MPS. 

Klotz and associates120 found that PEI-D-Im-type models catalyzed hydrolyses of 4-nitrocatechol sulfate by a two step mechanism resembling that of a natural enzyme. The polymer was reported to accelerate the rate by a factor of 1012 arm-pared to imidazole itself, and of 102 compared to a type-11A arylsulfatase enzyme. 

Familial demyelinative/dysmyelinative and axonal neuropathies may also be caused by impaired lysosomal lipid metabolism. Metachromatic leukodystrophy (sulfatide lipidosis) results from mutations of the arylsulfatase A gene, which encodes a lysosomal enzyme required for sulfatide turnover. Myelin is affected in both CNS and PNS, though dysfunction is restricted to the PNS in some patients, and the onset of symptoms can occur at any time between infancy and adulthood. Bone marrow transplantation can slow disease progression and improve nerve conduction velocities [57]. (See in Ch. 41.)... 

Enzyme activity (urease, amidase, dehydrogenase, pl-glucosidase, phosphatase, arylsulfatase, fluorescein diacetate hydrolysis) Laboratory incubation Indicates potential microbial activity and nutrient cycling reactions determined in nonstandard laboratory with specialized equipment highly spatially and temporally variable dependent upon organic inputs Dick et al. (1996) Parham et aL (2002)... 

EC 3.1.6.1) is a lysosomal enzyme that hydrolyzes sulfuric acid ester bonds. The enzyme exists in two forms, arylsulfatases A and B, that differ in substrate specificity and in sensitivity toward inhibitors [142][143]. Human tissues contain more arylsulfatase A than arylsulfatase B. The natural substrates of these enzymes are complex lipids such as cerebroside 3-sulfate, and gly-cosaminoglycans such as chondroitin 4-sulfate and derman sulfate [144], Deficiencies of these enzymes are associated with a number of lysosomal disorders. 

A number of enzymes known as sulfuric ester hydrolases (EC 3.1.6) are able to hydrolyze sulfuric acid esters. They comprise arylsulfatase (sulfatase, EC 3.1.6.1), steryl-sulfatase (steroid sulfatase, steryl-sulfate sulfohydrolase, arylsulfatase C, EC 3.1.6.2), choline-sulfatase (choline-sulfate sulfohydrolase, EC 3.1.6.6), and monomethyl-sulfatase (EC 3.1.6.16). Whereas mono-methyl-sulfatase is highly specific and does not act on higher homologues, arylsulfatase has a broad substrate specificity and is of particular significance in the hydrolysis of sulfate conjugates of phenols, be they endogenous compounds, drugs, or their metabolites [167-169],... 

Arylsulfatase [EC 3.1.6.1 ], also known simply as sulfatase, catalyzes the hydrolysis of a phenol sulfate, thereby producing a phenol and sulfate. This enzyme classification represents a collection of enzymes with rather similar specificities. (1) Steryl-sulfatase [EC3.1.6.2],also referred to as arylsulfatase C and steroid sulfatase, catalyzes the hydrolysis of 3-j8-hydroxyandrost-5-en-17-one 3-sulfate to 3-j8-hydroxyandrost-5-en-17-one and sulfate. The enzyme utilizes other steryl sulfates as substrates. (2) Cere-broside-sulfatase [EC 3.1.6.8], or arylsulfatase A, catalyzes the hydrolysis of a cerebroside 3-sulfate to yield a cerebroside and sulfate. The enzyme will also hydrolyze the galactose 3-sulfate bond present in a number of lipids. In addition, the enzyme will also hydrolyze ascorbate 2-sulfate and other phenol sulfates. 

This enzyme [EC 3.1.6.8], also known as arylsulfatase A, catalyzes the hydrolysis of a cerebroside 3-sulfate to produce a cerebroside and sulfate. The enzyme will also catalyze analogous reactions on the galactose 3-sulfate residues in a number of lipids as well as on ascorbate 2-sulfate and many phenol sulfates. 

For cells with /1-galactosidase deficiency (GM1 gangliosidosis or Morquio type as well as I-cell disease), the measured enzyme activity will be significantly lower than the true enzyme activity. In addition, cases of multiple sulfatase deficiency will also show low N-acetylgalactosamine-6-sulfatase activity. Therefore, arylsulfatase A or another sulfatase, as well as /1-galactosidase activities should also be determined in case of suspicious results. To exclude poor sample quality, the determination of a-mannosidase is recommended. 

All enzymes are measured at acidic pH with artificial fluorogenic substrates, except for arylsulfatase A, which is measured with a chromogenic substrate. The fluorogenic substrates are derivatives of 4-methylumbelliferone or 6-hexadecanoylamino-... 

In case of a deficiency of arylsulfatase A, at least one other sulfatase should be measured to exclude multiple sulfatase deficiency (see Chap. 4.1 for the assays of arylsulfatase and other sulfatases). Sulfatide excretion in urine should be measured (see assay below) and/or mutation analysis should to performed to confirm the diagnosis, especially if the clinical symptoms are atypical and in order to exclude a pseudodeficiency of arylsulfatase A. The enzyme should always be measured in the parents to check for the presence of compound heterozygosity of a metachromatic leukodystrophy and a pseudodeficiency allele. This is very important for the interpretation of the results of arylsulfatase A assays, especially when performed in asymptomatic or presymptomatic siblings or in the context of a prenatal diagnosis. Sulfatide should also be measured in case a normal arylsulfatase A activity is found in a patient with symptoms characteristic of (juvenile) metachromatic leukodystrophy. Increased urinary sulfatide excretion is indicative of an activator protein/saposin deficiency (Fig. 4.4.1). 

Reiter et al. (43) have shown that a second enzyme can also act to degrade SGG. They found that secondary lysosomes from rat liver contained not only arylsulfatase A, but also a lipase activity that could act to de-acylate SGG. Under the conditions used, more product was formed by the action of the lipase on SGG than by the action of arylsulfatase A. These workers also found that the latter enzyme could use the lyso-SGG as a substrate. It would be... 

Cadmium in the body is known to affect several enzymes. It is believed that the renal damage that results in proteinuria is the result of cadmium adversely affecting enzymes responsible for reabsorption of proteins in kidney tubules. Cadmium also reduces the activity of delta-aminolevulinic acid synthetase (Figure 10.3), arylsulfatase, alcohol dehydrogenase, and lipoamide dehydrogenase, whereas it enhances the activity of delta-aminolevulinic acid dehydratase, pyruvate dehydrogenase, and pyruvate decarboxylase. 

Arylsulfatase cleaves sulfate esters. Cerebroside sulfate is its natural substrate. The enzyme is also active toward p-nitrocatechol sulfate, which is the basis for this assay. 

The enzyme was prepared from human liver. This substrate is not hydrolyzed by arylsulfatase A. 

Figure 9.65 HPLC analysis of arylsulfatase B reaction with UDP-GalNAc-4-S The reaction mixture contained 5 mU of enzyme. (From Fluharty et al., 1982).

Acid phosphatase Alcohol dehydrogenase Alkaline phosphatase Amine oxidase Aminopeptidase P Angiotensin-converting enzyme Aniline hydroxylase ATPase Arylsulfatase Carboxypeptidase M Cyclooxygenase Cytochrome oxidase Endothelin-converting enzyme... 

Studies on the activity of rabbit sperm acrosomal enzymes have indicated that gossypol at 12-76 pM could significantly inactivate azocoll proteinase, acrosin, neuraminidase, and arylsulfatase. Hyaluronidase, p-glucuronidase, and acid phosphatase were also inhibited at a higher concentration of gossypol (380 pM) (Yuan et al., 1995). Since acrosomal enzymes play important roles in the fertilization process, the inhibition of... 

In the case of competitive inhibition the substrate and the inhibitor compete for the enzyme binding site. The same is true for product inhibition, where the accumulation of a product leads to a slow down of the enzyme reaction. Prominent examples are the inhibition of AP by phosphate, of arylsulfatase by sulfate, and of cholesterol oxidase by cholestenone. 

Histochemical observations. There was an increase in acid phosphatase and arylsulfatase activity in the region of basal epidermal cells, reaching a maximum at 3 h post-exposure. This was attributed to activation of lysosomal enzymes. At 8 and 19 h, post-exposure increased arylsulfatase staining of fibroblasts and histiocytes was noted. At 19 h, clusters of large AT-Pase positive mononuclear cells were identified just below the epidermis. These may have been derived from the Langerhans cells of the antigen presenting series. 

Arylsulfatase B (N-acetylgalactosamine 4-sulfatase) is a deficient enzyme in patients witti the genetic defect disease MPS VI. Like MPS I, GAGs are only partially broken down, and carbohydrate residues build relentlessly in the lysosomesof cells. Also like a-L-iduroni-dase replacement, the exogenous supply of arylsulfatase could breakdown the stored GAGs and cellular function could be restored. 

It is also of interest to note that the GRE-activating enzymes are not the only radical SAM proteins that act on a protein substrate AtsB catalyzes the formation of a Cct-formylglycine (2-amino-3-oxopropionic acid, FGly) on AtsA, thereby activating this arylsulfatase (see Section 8.17.3.8). 

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