Cerebroside sulfatase

CEREBROSIDE SULFATASE CERULOPLASMIN FERROXIDASE CEiCFo ATPase... 

Dubois, G., Harzer, K.. and Bauman, N., Very low arylsulfatase A and cerebroside sulfatase activities in leukocytes of healthy members of metachromatic leukodystrophy family. Am. J. Hum. Genet. 29, 191-194 (1977). 

Fischer, G., and Jatzkewitz, H., The activator of cerebroside sulfatase A model of the activation. Biochim. Biophys. Acta 528, 69-76 (1978). 

Harzer, K., StinshofF, K., Mraz, W., and Jatzkewitz, H., The patterns of arylsul tases A and B in human normal and metachromatic leukodystrophy tissues and their relationship to the cerebroside sulfatase activity. J. Neurochem. 20, 279-287 (1973). 

Jerfy, A., and Roy, A. B., Comparison of the arylsulfatase and cerebroside sulfatase activities of sulfatase A. Biochim. Biophys. Acta 293, 178-190 (1973). 

Porter, M. T., Fluharty, A. L., Trammell, J., and Kihara, M., A correlation of intracellular cerebroside sulfatase activity in fibroblasts with latency in metachroraatic leukodystrophy. Biochem. Biophys. Res. Commun. 44, 660-666 (1971a). 

The activator of cerebroside sulfatase (or sulfatide activator ) was purified by Fischer and Jatzkewitz (1975) from human liver and identified as a water-soluble glycoprotein with an isoelectric point at pH 4.3 and a molecular weight of approximately 22,000 Daltons. From kinetic and binding experiments and from the fact that this cofactor stimulated only the degradation of lipid substrates but not of artificial water-soluble ones, these authors concluded that the cofactor serves to solubilize the lipid by binding to it and extracting it from the membrane (or micelle). The resulting activator/lipid complex was assumed to be the true substrate of the enzymic reaction (Fischer and Jatzkewitz, 1977, 1978). 

A number of studies examined the enzymic basis for impairment of sulfatide catabolism in ML, which is probably located at the site of the sulfate bond. The search for a cerebroside-sulfatase in normals which would catalyze the reaction cerebroside-sulfate cerebroside + sulfuric acid (Jatzkewitz 1958, 1960, 1963) was unsuccessful for a number of years (Fujino and Negishi 1957 Green and Robinson 1960 Heald and Robinson 1961 Davison and Gregson 1962), but the enzyme was finally found in shellfish by Fujino and Negishi (1957). 

In 1963, Mehl and Jatzkewitz succeeded in isolating fractions with cerebroside-sulfatase activity from pig kidneys, and Bleszynski and Dzialoszynski (1965) purified soluble arylsulfatases from ox brain. A study by Mehl and Jatzkewitz (1965) on the significance of a lack of arylsulfatase in ML as reported by Austin (1963 a), and Austin et al. (1964 a, b), with 2-hydroxy-5-nitrophenyl-sulfate as substrate, resulted in the finding of two fractions with arylsulfatase activity in normal kidneys. While in ML the smaller of both fractions was present in normal concentration, the second component, and the predominant one in normals, was below the limits (0.005 o. d. units Mehl and Jatzkewitz 1965) of the method in ML. It seems that diminution or lack of this heat-labile fraction, which corresponds to the arylsulfatase A of Austin, is typical for ML, and according to Mehl and Jatzkewitz (1965), supports the assumption of a block in the degradation of ML between sulfatides and cerebrosides (see fig. 3). 

Recent studies in rabbit brain show a progressive physiologic increase in arylsulfatase and cerebroside-sulfatase after birth, with maximum activity upon completion of myelination. It is possible that a deficiency of the enzyme assumes significance at this time this seems relevant to the manifestation of ML after the first year of life. An interpretation of later onset, as in adult cases (Mehl and Jatzkewitz 1965 Hollander and Pilz 1964), is more difficult. Although here a different enzymic lesion is a possibility, a quantitatively less severe enzyme defect seems more likely. In a number of adult cases sulfatide storage was less than in infantile cases (Jatzkewitz et al. 1964 Svennerholm 1963), regardless of the speed of progression of the disease. 

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. 

Two enzymes have activities related to the metabolism of sulfatides a sulfatase, which is capable of hydrolyzing sulfatides to yield cerebroside and sulfate, and a sulfatide synthetase, which catalyzes the formation of cerebroside and a sulfate donor (phosphoa-denosine phosphosulfate). The exact role of these enzymes in the overall sulfatide metabolism is not clear. A galactosylglucosyl ceramide esterfied with sulfuric acid in position 3 of the galactose has been found in kidney. The dihexose ceramide sulfatide is believed to be synthesized from the neutral ceramide in presence of phosphoadenosine phosphosulfate. The synthetase is a microsomal enzyme. The sulfatase is believed to be a lysosomal enzyme. 

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