Application of HPLC to study the kinetics of a branched bi-enzyme system consisting of hypoxanthine-guanine phosphoribosyltransferase and xanthine oxidase-an important biochemical system to evaluate the efficiency of the anticancer drug 6-mercaptopurine in ALL cell line

Kalra, Sukirti ; Paul, Manash K. ; Balaram, Hemalatha ; Mukhopadhyay, Anup Kumar (2007) Application of HPLC to study the kinetics of a branched bi-enzyme system consisting of hypoxanthine-guanine phosphoribosyltransferase and xanthine oxidase-an important biochemical system to evaluate the efficiency of the anticancer drug 6-mercaptopurine in ALL cell line Journal of Chromatography: B, 850 (1-2). pp. 7-14. ISSN 1570-0232

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S15700...

Related URL: http://dx.doi.org/10.1016/j.jchromb.2006.10.012

Abstract

The thiopurine antimetabolite 6-mercaptopurine (6MP) is an important chemotherapeutic drug in the conventional treatment of childhood acute lymphoblastic leukemia (ALL). 6MP is mainly catabolized by both hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and xanthine oxidase (XOD) to form thioinosinic monophosphate (TIMP) (therapeutically active metabolite) and 6-thiouric acid (6TUA) (inactive metabolite), respectively. The activity of both the enzymes varies among ALL patients governing the active and the inactive metabolite profile within the immature lymphocytes. Therefore, an attempt was made to study the kinetic nature of the branched bi-enzyme system acting on 6MP and to quantitate TIMP and 6TUA formed when the two enzymes are present in equal and variable ratios. The quantification of the branched kinetics using spectrophotometric method presents problem due to the closely apposed gamma max of the substrates and products. Hence, employing an HPLC method, the quantification of the products was done with the progress of time. The limit of quantification (LOQ) of substrate was found to be 10 nM and for products as 50 nM. The limit of detection (LOD) was found to be 1 nM for the substrate and the products. The method exhibited linearity in the range of 0.01-100 μ M for 6MP and 0.05-100 μ M for both 6TUA and TIMP. The amount of TIMP formed was higher than that of 6TUA in the bi-enzyme system when both the enzymes were present in equivalent enzymatic ratio. It was further found that enzymatic ratios play an important role in determining the amounts of TIMP and 6TUA. This method was further validated using actively growing T-ALL cell line (Jurkat) to study the branched kinetics, wherein it was observed that treatment of 50 μ M 6MP led to the generation of 12 μ M TIMP and 0.8 μ M 6TUA in 6 h at 37 ° C.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Reverse-Phase HPLC; Branched Bi-Enzyme System; Acute Lymphoblastic Leukemia; 6-Mercaptopurine; 6-Thiouric Acid; Thioinosine Monophosphate
ID Code:1264
Deposited On:04 Oct 2010 07:58
Last Modified:30 Jan 2023 09:51

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