J3-glucuronidase

Enzymes. See also. Amylases, Calac-tosidases, j3-Glucuronidase. acting on pectic substances, 5, 79-102 degradation by. of starch and glycogen, 3, 251-310 17, 407-430 specificity of, in the domain of carbohydrates, 5,49-78... 

Fig. 8. Hypothesis on the controls of heme synthesis in the hepatic cell at both the transcriptional and translational levels. In the nucleus a repressor protein blocks transcription at the promoter end of the operator gene, thus preventing synthesis of the mRNA of ALA-synthetase. A 5 -H steroid removes the repression by interacting with the repressor protein. The level of the steroid is controlled by glucuronidation with UDPGA transferase which renders it inactive, and by hydrolysis with j3-glucuronidase which renders it active. In the cytoplasm heme represses the synthesis of ALA-synthetase at the translational level and thus its own synthesis. Excess heme is destroyed by heme oxygenase of the microsomes.

Phenol red glucuronide was determined after either HC1 or 3-glucuronidase hydrolysis. The presence of the glucuronide was confirmed by thin layer chromatography in three systems (J3). 

The enzymatic hydrolysis is the method of choice when undesired reactions are to be avoided. /Tglucosidases (or /J-glucuronidases) from Helix pomatia digestive juice are now commercially available. They usually show a good hydrolytic performance, even if sometimes need long time reactions (days). Other enzymes are reported to have been used to specifically hydrolize saccharidic bonds like hesperidinase, /J-xylosidase, j3-galactosidase, and mixed crude enzymes like cellulase. 

In the field of aldobiouronic acid derivatives an ingenious method has been devised for the preparation of radioactive disaccharides for use as substrates for o-L-iduronidase, jS-D-glucuronidase, and 2-sulpho-L-iduronate 2-sulphatase. Heparin was cleaved by the deamination procedure and the products were reduced using sodium borotritide to afford access to a-L-idopyranosyluronic and j3-D-glucopyranosyluronic acid derivatives of 2,5-anhydro-D-[l- H]mannitol. Acidic treatment in methanol of the water-soluble polysaccharides of wobaku wood, followed by acetylation, have led to the isolation of the anhydride derivative (53) which was concluded to arise by way of the corresponding aldo-... 

With phenolphthalein j3-D-glucopyranosyluronic acid as substrate in a human serum jS-D-glucuronidase assay, centrifugation at high speed after addition of alkali was required to minimize blanks.Optimal substrate concentration was 3-6 mM excess substrate was inhibitory. 

The intracellular localization of exogenously supplied human platelet 3-D-glucuronidase in cultured skin fibroblasts derived from a j3-D-glucuronidase-deficient patient was studied.Four cellular fractions were obtained by... 

A pool of acid hydrolases exists within the acellular lining material of the alveoli and distal airways of the lungs.These extracellular hydrolases, obtained using pulmonary lavage procedures, appear to be of a selected variety insofar as some hydrolases (i8-D-2-acetamido-2-deoxyglucosidase and a-D-mannosidase) are highly active while others (j3-D-glucuronidase and arylsulphatase) are barely detectable (see p. 421). 

A novel polysaccharide gel, which has been isolated from the fruit of Thauma-tococcus danielli, contains residues of L-arabinose, D-xylose, D-glucuronic acid and its 4-0-methyl ether in the ratio 1.0 7.2 1.91 0.66. All of the uronic acid residues were oxidized by periodate and, from the results of methyla-tion analysis, the structure was found to be highly branched. Many of the uronic acid residues were removed by the action of j3-D-glucuronidase but the gel was not completely depolymerized by this treatment. 

The effect of cortisone and. thyroxine on j8-D-glucuronidase levels in rat forebrain and cerebellum have been examined during early postnatal development. To investigate the chemical relationships between rat liver lysosomal and microsomal j3-D-glucuronidase, which are essentially identical catalytically and in reactivity with antibody and are similar in molecular weight, the two enzymes were isolated by procedures in which modifications of the proteins were avoided. The enzymes were found to differ in both carbohydrate and amino-acid compositions. The microsomal enzyme contained much more D-mannose and, in contrast to the lysosomal enzyme, contained neuraminic acid but no D-glucose. 

Gel electrophoresis showed that rabbit Oryctolegus cuniculus) and, probably, rat (Ratius norvegiciis) livers contain variants of jS-D-glucuronidase corresponding to those in mouse Mus musculus) tissues.Microsomal and lysosomal fractions from rabbit liver differed only quantitatively in the j3-D-glucuronidases present. 

Treatment of hyaluronic acid with hydrazine removed some of the A -acetyl groups, which were reconstituted on reacetylation with tritiated acetic anhydride the tritiated mucopolysaccharide was used as a substrate in a semimicro assay for hyaluronidase. Tritium-labelled hyaluronic acid, labelled by the tritium-recoil technique, has been treated with j8-D-glucuronidase to yield tritiated oligosaccharides containing terminal, non-reducing 2-acetamido-2-deoxy-j3-D-glucopyranosyl residues. ... 

Decrease of rat liver glycogen by 45 and 68% has been shown 30 ami 120 minutes after glucagon injection. Botti the kidney and spleen glycogen ami j3-glucuronidaae, and the liver 3-glucuronidase activity are not modified by glucagon (Dohrmaim ei al., 1964, 1966). 

After whole body Co irradiation of male rats 750 r, LDm for 14 days), lysosomal enzymes increased in the first 3 days although the extent of the increase as a function of time differed in the various enzymes and also from one tissue to another. Irradiation enhanced the activity of all enzymes except muramidase in the brain, muramidase and j3-glueuronidase in the small intestines, and acid RNase and DNase in the heart jS-galactosidasc, /3-glucuronidase, and aryl sulfatase were enhanced in the liver. Within 2-6 days postirradiation the activities of lysosomal enzymes decreased except for heart RNase, liver muramidase, and small intestine /3-gaiactosid-ase, /3-glucuroiiidase, and aryl sulfatase (Noamaii et al., 1968). 

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