2002-60-0Relevant articles and documents
Purines oxidation by immobilized xanthine oxidase on magnetic polysiloxane-polyvinyl alcohol composite
Neri, David F.M.,Bernardino, Débora P.B.,Beltr?o, Eduardo I.C.,Carvalho Jr., Luiz B.
, p. 210 - 214 (2011)
Bovine milk xanthine oxidase (XOD, E.C. 1.17.3.2) was covalently immobilized, via glutaraldehyde, on magnetic polysiloxane-polyvinyl alcohol (mPOS-PVA) particles yielding a preparation containing 9.5 ± 0.5 μg of protein per mg of support and specific activity of 36.3 ± 7.8 mU/mg of protein (55.0 ± 11.7% of the free enzyme). Optimal pH (8.8) and temperature (60 °C) were slightly higher than those established for the free enzyme (8.2 and 55 °C, respectively). No decrease of activity was observed after five reuses and only 17% was lost at the tenth reuse. The apparent Michaelis constant estimated for the mPOS-PVA-XOD (8.86 ± 0.88 μM) was not statistically different from the free enzyme (7.48 ± 1.01 μM). The 6-mercaptopurine oxidation catalyzed by the mPOS-PVA-XOD followed the same pathway described for the free enzyme, namely, 6-mercaptopurine → 6-mercapto-8-hydroxypurine → 6-thiouric acid, and no 6-thioxanthine was formed.
Thermodynamic quantities for different steps involved in the mechanism of the oxidation of 6-mercaptopurine by diperiodatocuprate(III) in aqueous alkaline medium
Naik, Keerti M.,Nandibewoor, Sharanappa T.
, p. 123 - 136 (2011)
The kinetics of oxidation of 6-mercaptopurine (6-MP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.01mol/dm3 was studied spectrophotometrically. The reaction between DPC and 6-MP in an alkaline medium exhibits 1:4 stoichiometry (6-MP:DPC). The reaction is of first order in [DPC] and has less than unit order in both [6-MP] and [alkali]. However, the order of [6-MP] and [alkali] changes from first order to zero order as their concentration increases. Intervention of free radicals was observed in the reaction. An increase in periodate concentration decreases the rate. The oxidation reaction in an alkaline medium has been shown to proceed via a monoperiodatocuprate(III)-6-MP complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main oxidative products were identified by spot test, IR, GC-MS and HPLC studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to a slow step of the mechanism are computed and discussed, and thermodynamic quantities are also determined. Figure Presented.
In vitro oxidative metabolism of 6-mercaptopurine in human liver: Insights into the role of the molybdoflavoenzymes aldehyde oxidase, xanthine oxidase, and xanthine dehydrogenase
Choughule, Kanika V.,Barnaba, Carlo,Joswig-Jones, Carolyn A.,Jones, Jeffrey P.
, p. 1334 - 1340 (2017/01/22)
Anticancer agent 6-mercaptopurine (6MP) has been in use since 1953 for the treatment of childhood acute lymphoblastic leukemia (ALL) and inflammatory bowel disease. Despite being available for 60 years, several aspects of 6MP drug metabolism and pharmacok
