0-Glucuronidases

Erythrocyte-entrapped P-glucuronidase has been retained in the circulation and in the Hver of P-glucuronidase-deficient mice for longer periods of... 

Rabbit peritoneal neutrophils were harvested and their release of p-glucuronidase was measured at 37°C, as described previously (13). For indo-1, neutrophils were washed twice in a calcium-free buffer, then loaded with 15 indo-1 acetoxymethyl ester (24) for 40 min at 37 C at a density of 5 x 10 cells/ml. The cells were then washed twice more in calcium-free buffer, resuspended to a density of 1 X 10 cells/mL, and kept on ice. Prior to fluorometry, cells were diluted 4x with the appropriate buffer at 37 C. For CTC, neutrophils were incubated with 20 pH CTC at 37°C in the spectrofluorometer cuvette. All measurements were carried out using an SLH-Aminco SPF 500C fluorospectrometer interfaced with an IBM PC microcomputer. 

Figure 4. Effect of hyperosmolality on lysosomal enzyme release from rabbit neutrophils. Cells were preincubated 10 min at 37 C in either regular HEPES buffer at 320 mosmol/kg ( ) or in HEPES buffer with 0.3-M sucrose at 680 mosmol/kg ( ), 5 Mg/mL cyto-chalasin B was added, cells were stimulated with FMLP, and p-glucuronidase was released into the medium during a 6-min period measured.

Figure 5. Inhibition of lysosomal enzyme release from neutrophils by increased osmotic strength. Cells were preincubated for 10 min at 37°C in regular buffer containing no additions (o), or containing sodium sulfate ( ), sodium HEPES ( ), or sucrose ( ) to increase the osmotic strength. Cells were treated with cyto-chalasin B (5 arid FMLP (10" M) and p-glucuronidase was...

MIM 253200) Sly (MIM 253220) MPS VII sulfatase (arylsulfatase B) P-Glucuronidase Dermatan sulfate, heparan sulfate, chondroitin... 

After exhaustive hydrolysis with bovine liver 3-glucuronidase. Trace -<0.01% administered dose. 

R. A. Jeffer.son, Beta-glucuronidase (GUS) transposons for ecological and genetic studies of rhizobia and other gram-negative bacteria. Microbiology 14l 69l (1995). 

Several extraction techniques have also been described that use enzymatic or chemical reactions to improve extraction efficiency. A technique that has been used to increase the overall recovery of the marker residue is enzymatic hydrolysis to convert specific phase II metabolites (glucuronides or sulfates) back into the parent residue. Cooper etal used a glucuronidase to increase 10-fold the concentration of chloramphenicol residues in incurred tissue. As an example of a chemical reaction, Moghaddam et al. used Raney nickel to reduce thioether bonds between benomyl and polar cellular components, and as a result achieved a substantially improved recovery over conventional solvent extraction. In choosing to use either of these approaches, thorough characterization of the metabolism in the tissue sample must be available. 

Based on the data from animal studies, diisopropyl methylphosphonate is principally excreted in the urine as the metabolite IMPA (Hart 1976 Ivie 1980). Chromatographic behavior of urinary metabolites does not change after the urine is treated with glucuronidase and sulfatase, so there is no conjugation of diisopropyl methylphosphonate or IMPA by microsomal enzymes (Hart 1976). There was minimal excretion of diisopropyl methylphosphonate metabolites in bile (Hart 1976) or in the milk of a lactating cow (<1%) (Palmer et al. 1979). 

D-Saccharic acid 1,4-lactone (SAL 5-10 mM), a selective inhibitor of/3-glucuronidase [29], is often included in UGT reactions for improving yield. As /3-glucuronidases and UGTs have different optimal pH ranges, use of SAL in preparative-scale reactions may be avoided. 

Zenser, T.V., Lakshmi, V.M. and Davis, B.B. (1999) Human and Escherichia coli /3-glucuronidase hydrolysis of glucuronide conjugates of benzidine and 4-aminobiphenyl, and their hydroxy metabolites. Drug Metabolism and Disposition The Biological Fate of Chemicals, 27, 1064—1067. 

Kushinsky, S. and Chen, V.L. (1967) The inhibition of/3-glucuronidase from bovine liver by 1,4-saccharolactone. Comparative Biochemistry and Physiology, 20, 535—542. 

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