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Beringer A, Citterio-Quentin A, Otero RO, Gustin C, Clarke R, Salvi JP, Boulieu R. Determination of inosine 5'-monophosphate dehydrogenase activity in red blood cells of thiopurine-treated patients using HPLC. J Chromatogr B Analyt Technol Biomed Life Sci 2017; 1044-1045:194-199. [PMID: 28110955 DOI: 10.1016/j.jchromb.2017.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/30/2016] [Accepted: 01/05/2017] [Indexed: 01/25/2023]
Abstract
Thiopurine drugs are commonly used in immune diseases and to a lesser extent, in transplant rejection prophylaxis: however interindividual variability in drug response and in the occurrence of adverse events is observed. Genetic variation in thiopurine S-methyltransferase (TPMT) doesn't completely explain the occurrence of all adverse events and drug response variability. The potential implication of other enzymes involved in thiopurine metabolism, such as ITPA, has been investigated over the last decade but little data is available on inosine 5'-monophosphate dehydrogenase (IMPDH) in patients treated with thiopurine drugs. The authors reported a HPLC method to determine IMPDH activity in the red blood cells (RBCs) of thiopurine-treated patients. IMPDH activity was evaluated by enzymatic conversion of inosine 5'-monophosphate (IMP) to xanthosine 5'-monophosphate (XMP). The XMP formed was analyzed on a Luna® NH2 stationary phase, a weak anion exchange phase that exhibits both ionic and hydrophobic properties. XMP was eluted below 15min. Intra-assay and inter-assay precisions were below 9% for RBCs supplemented with 2, 40 and 80μmol/L of XMP. IMPDH activity was measured in adults without thiopurine treatment as well as in adult and paediatric patients treated with thiopurines. A wide interindividual variability in IMPDH activity in RBCs was observed. No difference in IMPDH activity was found between untreated subjects and adult and paediatric patients on thiopurine therapy (median value 11.8, 7.9 and 7.7nmol XPM/g Hb/h respectively). The method described is useful in the determination of IMPDH phenotype from patients on thiopurine therapy and in the investigation of the potential relationship between IMPDH activity in RBCs and the occurrence of adverse events and drug response variability.
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Affiliation(s)
- Audrey Beringer
- Université de Lyon, Université Lyon 1, UMR CNRS 5305, Pharmacie Clinique, Pharmacocinétique et Evaluation du Médicament, Lyon, France; Hospices Civils de Lyon, Groupement Hospitalier Edouard Herriot, Laboratoire de Biologie Médicale Multi Sites du CHU de Lyon, unité de Pharmacocinétique Clinique, Lyon, France
| | - Antony Citterio-Quentin
- Université de Lyon, Université Lyon 1, UMR CNRS 5305, Pharmacie Clinique, Pharmacocinétique et Evaluation du Médicament, Lyon, France; Hospices Civils de Lyon, Groupement Hospitalier Edouard Herriot, Laboratoire de Biologie Médicale Multi Sites du CHU de Lyon, unité de Pharmacocinétique Clinique, Lyon, France
| | - Rebeca Obenza Otero
- Université de Lyon, Université Lyon 1, UMR CNRS 5305, Pharmacie Clinique, Pharmacocinétique et Evaluation du Médicament, Lyon, France
| | - Clémence Gustin
- Université de Lyon, Université Lyon 1, UMR CNRS 5305, Pharmacie Clinique, Pharmacocinétique et Evaluation du Médicament, Lyon, France; Hospices Civils de Lyon, Groupement Hospitalier Edouard Herriot, Laboratoire de Biologie Médicale Multi Sites du CHU de Lyon, unité de Pharmacocinétique Clinique, Lyon, France
| | - Rebecca Clarke
- Université de Lyon, Université Lyon 1, UMR CNRS 5305, Pharmacie Clinique, Pharmacocinétique et Evaluation du Médicament, Lyon, France; School of Pharmacy and Pharmaceuticals Sciences, Trinity College Dublin, Dublin, Ireland
| | - Jean-Paul Salvi
- Université de Lyon, Université Lyon 1, UMR CNRS 5305, Pharmacie Clinique, Pharmacocinétique et Evaluation du Médicament, Lyon, France
| | - Roselyne Boulieu
- Université de Lyon, Université Lyon 1, UMR CNRS 5305, Pharmacie Clinique, Pharmacocinétique et Evaluation du Médicament, Lyon, France; Hospices Civils de Lyon, Groupement Hospitalier Edouard Herriot, Laboratoire de Biologie Médicale Multi Sites du CHU de Lyon, unité de Pharmacocinétique Clinique, Lyon, France.
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Borioni A, Bastanzio G, Delfini M, Mustazza C, Sciubba F, Tatti M, Del Giudice MR. High resolution NMR conformational studies of new bivalent NOP receptor antagonists in model membrane systems. Bioorg Chem 2011; 39:59-66. [PMID: 21211814 DOI: 10.1016/j.bioorg.2010.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 12/06/2010] [Accepted: 12/07/2010] [Indexed: 11/19/2022]
Abstract
The interaction of new bivalent NOP receptor antagonists with dodecyl phosphatidylcholine micelles and DMPC/cholesterol liposomes was investigated in solution by high resolution NMR. The ligands are structurally related to the NOP antagonist JTC-801 plus a propanediamine or heptanediamine spacer between the pharmacophoric units. Ligand internuclear distances were derived from 2D NOESY data and applied to molecular modelling calculations as conformational restraints. NMR experiments on micelles evidenced that the ligands closely approached the micelles but gave no hints on the preferential conformations of the interacting ligands. Results from NMR experiments in the presence of liposomes clearly indicated that both ligands strongly interacted with the bilayer assuming a preferential folded conformation with the quinoline arms superimposing on each other. The finding suggested that these strongly lipophilic pharmacophores could localize in the native receptorial membrane in the form of a depot, gaining access to the recognition site via the lipid bilayer.
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Affiliation(s)
- Anna Borioni
- Istituto Superiore di Sanità, Dipartimento del Farmaco, Viale Regina Elena 299, Rome, Italy.
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Riera TV, Wang W, Josephine HR, Hedstrom L. A kinetic alignment of orthologous inosine-5'-monophosphate dehydrogenases. Biochemistry 2008; 47:8689-96. [PMID: 18642884 PMCID: PMC2646883 DOI: 10.1021/bi800674a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
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IMP dehydrogenase (IMPDH) catalyzes two very different chemical transformations, a dehydrogenase reaction and a hydrolysis reaction. The enzyme toggles between the open conformation required for the dehydrogenase reaction and the closed conformation of the hydrolase reaction by moving a mobile flap into the NAD site. Despite these multiple functional constraints, the residues of the flap and NAD site are highly diverged, and the equilibrium between open and closed conformations (Kc) varies widely. In order to understand how differences in the dynamic properties of the flap influence the catalytic cycle, we have delineated the kinetic mechanism of IMPDH from the pathogenic protozoan parasite Cryptosporidium parvum (CpIMPDH), which was obtained from a bacterial source through horizontal gene transfer, and its host counterpart, human IMPDH type 2 (hIMPDH2). Interestingly, the intrinsic binding energy of NAD+ differentially distributes across the dinucleotide binding sites of these two enzymes as well as in the previously characterized IMPDH from Tritrichomonas foetus (TfIMPDH). Both the dehydrogenase and hydrolase reactions display significant differences in the host and parasite enzymes, in keeping with the phylogenetic and structural divergence of their active sites. Despite large differences in Kc, the catalytic power of both the dehydrogenase and hydrolase conformations are similar in CpIMPDH and TfIMPDH. This observation suggests that the closure of the flap simply sets the stage for catalysis rather than plays a more active role in the chemical transformation. This work provides the essential mechanistic framework for drug discovery.
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Affiliation(s)
- Thomas V Riera
- Departments of Biochemistry and Chemistry, Brandeis University, Waltham, Massachusetts 02454, USA
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Lee YC, Jackson PL, Jablonsky MJ, Muccio DD. Conformation of 3'CMP bound to RNase A using TrNOESY. Arch Biochem Biophys 2007; 463:37-46. [PMID: 17416340 DOI: 10.1016/j.abb.2007.02.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Accepted: 02/09/2007] [Indexed: 11/30/2022]
Abstract
The conditions for accurately determining distance constraints from TrNOESY data on a small ligand (3'CMP) bound to a small protein (RNase A, <14 kDa) are described. For small proteins, normal TrNOESY conditions of 10:1 ligand:protein or greater can lead to inaccurate structures for the ligand-bound conformation due to the contribution of the free ligand to the TrNOESY signals. By using two ligand:protein ratios (2:1 and 5:1), which give the same distance constraints, a conformation of 3'CMP bound to RNase A was determined (glycosidic torsion angle, chi=-166 degrees ; pseudorotational phase angle, 0 degrees < or = P < or =36 degrees ). Ligand-protein NOESY cross peaks were also observed and used to dock 3'CMP into the binding pocket of the apo-protein (7rsa). After energy minimization, the conformation of the 3'CMP:RNase A complex was similar to the X-ray structure (1 rpf) except that a C3'-endo conformation for the ribose ring (rather than C2'-exo conformation) was found in the TrNOESY structure.
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Affiliation(s)
- Yi-Chien Lee
- National Cancer Institute at Frederick, Laboratory of Medical Chemistry, 376 Boyles Street, Building 376, Frederick, MD 21702, USA
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