Studies on sulphatases. 9. The arylsulphatases of mammalian livers

Abstract

Kinetic data for the hydrolysis of potassium pacetylphenyl sulphate by fresh rat liver suspensions suggested that the arylsulphatase activity so observed could be attributed to a single enzyme (Dodgson, Spencer & Thomas, 1953) which was later found to be localized mainly in the microsomes of the liver cell (Dodgson, Spencer & Thomas, 1954a). Preliminary attempts to purify the microsome enzyme (unpublished data) were handicapped by its insolubility in various buffers and salt solutions of widely differing pH even after treatment of the liver by acetone-drying, alternate freezing and thawing, or use of the tissue disintegrator (Mickle, 1948). Sulphate and phosphate ions had little effect on the enzyme. These results contrast sharply with the arylsulphatase pattern reported for ox liver (Roy, 1953a, b; 1954). Using dipotassium 2-hydroxy-5nitrophenyl sulphate as the assay substrate, Roy was able to separate two arylsulphatases from the soluble material of acetone-dried ox liver and both enzymes were strongly inhibited by sulphate and phosphate ions. With the same substrate the arylsulphatase activity of mouse liver was found to be mainly concentrated in the mitochondria (Roy, 1953a). The present work, a preliminary report of which has already appeared (Dodgson, Spencer & Thomas, 1954 b), shows how the occurrence of three different arylsulphatases in mammalian livers enables these contrasting findings to be reconciled. METHODS Arylsulphates. Potassium p-acetylphenyl sulphate (APS) and potassium p-nitrophenyl sulphate (NPS) were prepared by the method of Burkhardt & Lapworth (1926) and dipotassium 2-hydroxy-5-nitrophenyl sulphate (nitrocatechol sulphate, NCS) according to Roy (1953a). Measurement of arylnulphata8e activity. The method previously used for APS (Dodgson, Lewis & Spencer, 1953) was also adopted for NPS but using the Am.. and e,,. determined for p-nitrophenol (Dodgson & Spencer, 1953). The use of NPS was restricted to liver extracts, as recoveries of p-nitrophenol from fresh liver suspensions are low (Dodgson & Spencer, 1953). The faint turbidity of the final solutions was the same in both test and controls and duplicate determinations were satisfactory. Turbidity only inter

Studies on metabolism of vitamin A. 2. Enzymic synthesis and hydrolysis of phenolic sulphates in vitamin-A-deficient rats

“…Existing literature shows that the relative distribution of the arylsulphatases A, B and C was studied with whole homogenates or with acetonedried preparations of animal tissues (Robinson, Smith & Williams, 1951;Dodgson et al 1955;Dodgson, Spencer & Wynn, 1956;Pulkinen, 1961). A reinvestigation of their distribution in rat tissues, the mitochondrial fraction being used for the sulphatases A and B and the microsomal fraction for sulphatase C, instead of the whole homogenates, was therefore undertaken ( Table 2).…”

“…Three arylsulphatases (A, B and C) have been shown (Dodgson, Spencer & Thomas, 1955) to exist in animal tissues, A and B being of mitochondrial origin, whereas C is a microsomal enzyme. The mitochondrial fractions isolated from 10% homogenates of tissues in 0 25M-sucrose, prepared according to Schneider & Hogeboom (1950) Proteins were estimated by the biuret method (Gornall, Bardawill & David, 1949).…”

The biochemistry of epithelia: enzyme levels in bronchial and tracheal epithelia of smokers and non-smokers and in bronchial carcinoma

“…The cytoplasmic localization of these enzymes in human tracheobronchial epithelial cells is in accord with the results obtained for the same enzymes in rat-liver cells by the technique of differential centrifuging of cell homogenates. Although a good correlation between RNA content of the cells and enzymes which are localized in the endoplasmic reticulum might have been expected, a similar high degree of correlation was seen with acid phosphatase and arylsulphatases A plus B, which are found in the lysozymes (Viala & Gianetto, 1955;Dodgson, Spencer & Thomas, 1954), and f,-glucuronidase, which is of mixed mitochondrialysozyme localization (de Duve, Pressman, Gianetto, Wattiaux & Appelmans, 1955). The correla--tion of RNA content with the activities of these various enzymes may indicate some direct relationship, or, both the RNA content and the enzyme activities may simply be reflexions of the variation in cytoplasmic size of the cell (Fig.…”

The Arylsulphatases and Related Enzymes in the Livers of Some Lower Vertebrates

“…It is impossible to provide data for the effects of anions on the latter enzyme because of its sensitivity to cations but it is clear from previous work that sulphate, chloride and phosphate ions have little effect on the type I arylsulphatases of the eutheria (Dodgson, Spencer and Thomas, 1955;Roy, 1956b). It is obvious that although the three enzymes have rather similar Km values for nitrophenyl sulphate they differ in other respects, particularly in the lower values of their pH optima and their sensitivity to sulphate and phosphate ions, the effect of the latter on the opossum enzyme being particularly striking.…”