Dmd056374 695..699
نویسندگان
چکیده
When investigating the potential for xanthine oxidase (XO)-mediated metabolism of a new chemical entity in vitro, selective chemical inhibition experiments are typically used. Most commonly, these inhibition experiments are performed using the inhibitor allopurinol (AP) and commercially prepared human liver cytosol (HLC) as the enzyme source. For reasons detailed herein, it is also a common practice to perfuse livers with solutions containing AP prior to liver harvest. The exposure to AP in HLC preparations could obviously pose a problem for measuring in vitro XO activity. To investigate this potential problem, an HPLC-MS/MS assay was developed to determine whether AP and its primary metabolite, oxypurinol, are retained within the cytosol for livers that were treated with AP during liver harvest. Differences in enzymatic activity for XO and aldehyde oxidase (AO) in human cytosol that can be ascribed to AP exposure were also evaluated. The results confirmed the presence of residual AP (some) and oxypurinol (all) human liver cytosol preparations that had been perfused with an AP-containing solution. In every case where oxypurinol was detected, XO activity was not observed. In contrast, the presence of AP and oxypurinol did not appear to have an impact on AO activity. Pooled HLC that was purchased from a commercial source also contained residual oxypurinol and did not show any XO activity. In the future, it is recommended that each HLC batch is screened for oxypurinol and/or XO activity prior to testing for XO-mediated metabolism of a new chemical entity.
منابع مشابه
Light energy conversion in Halobacterium halobium.
INTRODUCTION .............................................................. 682 PURPLE MEMBRANE ....................................................... 683 BACTEBRIORHODOPSIN: A LIGHT-DRIVEN PUMP FOR PROTONS ..... ..... 686 SECONDARY GRADIENTS: TRANSMEMBRANE MOVEMENTS OF Na+, K', AND Cl................................................................... 689 AMINO ACID TRANSPORT ............... ....
متن کاملSports Med 2005; 35 (8): 685-715
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 686 1. Auto Racing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 687 2. Baseball . . . . . . . . . . . . . . . . . . . . . . ...
متن کاملAnimal behavior: a continuing synthesis.
CONTENTS INTRODUCTION ..................................................................................................................... 676 The Historical Synthesis of Animal Behavior .................................................... 676 Current Status of the Synthesis .......................................................................... 677 A Reconsideration of the Synthesis .........
متن کاملThe contribution of amino acid region ASP695-TYR698 of factor V to procofactor activation and factor Va function.
There is strong evidence that a functionally important cluster of amino acids is located on the COOH-terminal portion of the heavy chain of factor Va, between amino acid residues 680 and 709. To ascertain the importance of this region for cofactor activity, we have synthesized five overlapping peptides representing this amino acid stretch (10 amino acids each, HC1-HC5) and tested them for inhib...
متن کامل