Hydrolysis 3-glucuronidase

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

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. 

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. 

Dray J, Dray F, Tiller F, Ulman A (1972) Hydrolysis of urine metabolites of different steroid hormons by b-glucuronidase of Escherichia coli. Ann Inst Pasteur 123 853-857... 

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). 

While some of these reactions are mediated by enzymes, e.g., glucuronidase, which hydrolyze glucuronide conjugates, many others are nonenzy-matic. These are driven by the electrophilicity of the substrates, which renders them susceptible to attack by the HO- anion (specific base catalyzed hydrolysis) or by other bases (general base catalyzed hydrolysis). A semblance of order in such a heterogeneous group of reactions is, thus, far from obvious. 

F. M. Brunelle, P. K. Verbeeck, Conjugation-Deconjugation Cycling of Diflunisal via Beta-Glucuronidase Catalyzed Hydrolysis of Its Acyl Glucuronide in the Rat , Life Sci. 

T. V. Zenser, V. M. Lakshmi, B. B. Davis, Human and Escherichia coli /3-Glucuronidase Hydrolysis of Glucuronide Conjugates of Benzidine and 4-Aminobiphenyl, and Their Hydroxy Metabolites , Drug Metab. Dispos. 1999, 27, 1064 - 1077. 

Xylans are heteropolysaccharides which are depolymerized by j8-l,4-D-endoxylanases. Due to the abundance and variety of substituents in native xylans, different accessory enzymes are also needed for the total hydrolysis of xylan. The knowledge of a-glucuronidase, a-arabinosidase, and acetyl xylan- and feruloyl esterases has increased considerably in recent years. In addition to acting in synergism with endoxylanases and )8-xylosidase for the complete hydrolysis of xylan, some of these accessory enzymes are also capable of changing the structure of polymeric xylans. 

This requires hydrolysis, and fermentation or transformation steps. While enzymes degrading the heteroxy-lan are known as xylanases, they also require the additional actions of / -xylosidases, a-arabinosidases, a-glucuronidases and certain esterases for total hydrolysis. 

The xylanolytic enzyme system of Trichoderma reesei, a well-known producer of cellulolytic enzymes, is versatile and well suited for the total hydrolysis of different xylans. It consists of two major, specific and several non-specific xylanases, at least one / -xylosidase, a-arabinosidase and a-glucuronidase and at least two acetyl esterases. The hydrolysis of polymeric xylans starts by the action of endoxylanases. The side-groupcleaving enzymes have their highest activities towards soluble, short xylo-oligosaccharides, and make the substituted oligosaccharides again accessible for xylanases and / -xylosidase. 

Following pretreatment, samples can be further treated with -glucuronidase (25-27) to achieve hydrolysis of conjugated chloramphenicol residues. It... 

Glucuronidase hydrolysis, EtOAc extn, liq-liq partn, SPE cleanup... 

Enzymatic digestion with protease, -glucuronidase hydrolysis, H2O/ acetone extn, cleanup on tandem basic alumina column and Bio-Rex anion-exchange membrane, liq-liq partns... 

A (tissues), Amberlite XAD-2 addn, -glucuronidase-arylsulfatase hydrolysis (urine, liver, kidney), on-line lAC cleanup, trace enrichment on Chrompack Cis, preconcn column and switching to analytical column... 

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