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  • Recognition of benztropine by the dopamine transporter (DAT) differs from that of the classical dopamine uptake inhibitors cocaine, methylphenidate, and mazindol as a fun ... 15879005

    Binding of cocaine to the dopamine transporter (DAT) protein blocks synaptic dopamine clearance, triggering the psychoactive effects associated with the drug; the discrete drug-protein interactions, however, remain poorly understood. A longstanding postulate holds that cocaine inhibits DAT-mediated dopamine transport via competition with dopamine for formation of an ionic bond with the DAT transmembrane aspartic acid residue D79. In the present study, DAT mutations of this residue were generated and assayed for translocation of radiolabeled dopamine and binding of radiolabeled DAT inhibitors under identical conditions. When feasible, dopamine uptake inhibition potency and apparent binding affinity K(i) values were determined for structurally diverse DAT inhibitors. The glutamic acid substitution mutant (D79E) displayed values indistinguishable from wild-type DAT in both assays for the charge-neutral cocaine analog 8-oxa-norcocaine, a finding not supportive of the D79 "salt bridge" ligand-docking model. In addressing whether the D79 side chain contributes to the DAT binding sites of other portions of the cocaine pharmacophore, only inhibitors with modifications of the tropane ring C-3 substituent, i.e., benztropine and its analogs, displayed a substantially altered dopamine uptake inhibition potency as a function of the D79E mutation. A single conservative amino acid substitution thus differentiated structural requirements for benztropine function relative to those for all other classical DAT inhibitors. Distinguishing the precise mechanism of action of this DAT inhibitor with relatively low abuse liability from that of cocaine may be attainable using DAT mutagenesis and other structure-function studies, opening the door to rational design of therapeutic agents for cocaine abuse.
    Document Type:
    Reference
    Product Catalog Number:
    MAB369
    Product Catalog Name:
    Anti-Dopamine Transporter Antibody, NT, clone DAT-Nt

  • Immobilization of glutaryl-7-aminocephalosporanic acid acylase on silica gel and enhancement of its stability. 12665670

    Glutaryl-7-aminocephalosporanic acid (GL-7-ACA) acylase is an enzyme that converts GL-7-ACA to 7-aminocephalosporanic acid, a starting material for semisynthetic cephalosporin antibiotics. In this study, optimal conditions for the immobilization of GL-7-ACA acylase were determined by experimental observations and statistical methods. The optimal conditions were as follows: 1.1 M phosphate buffer (pH 8.3) as buffer solution, immobilization temperature of 20 degrees C, and immobilization time of 120 min. Unreacted aldehyde groups were quenched by reaction with a low-molecular-weight material such as L-lysine, glycine, and ethanolamine after immobilization in order to enhance the activity of immobilized GL-7-ACA acylase. The activities of immobilized GL-7-ACA acylase obtained by using the low-molecular-weight materials were higher than those obtained by immobilized GL-7-ACA acylase not treated with low-molecular-weight materials. In particular, the highest activity of immobilized GL-7-ACA acylase was obtained using 0.4% (v/v) ethanolamine. We also investigated the effect of sodium cyanoborohydride in order to increase the stability of the linkage between the enzyme and the support. The effect on operational stability was obvious: the activity of immobilized GL-7-ACA acylase treated with 4% (w/w) sodium cyanoborohydride remained almost 100% after 20 times of reuse.
    Document Type:
    Reference
    Product Catalog Number:
    03-104
    Product Catalog Name:
    RIPAb+ CUGBP1 - RIP Validated Antibody and Primer Set

  • Modulation of choroidal neovascularization by subretinal injection of retinal pigment epithelium and polystyrene microbeads. 19158960

    The study was conducted to create a rapidly developing and reproducible animal model of subretinal choroidal neovascularization (CNV) that allows a time-dependent evaluation of growth dynamics, histopathologic features, and cytokine expression.C57BL/6 and chemoattractant leukocyte protein-2 deficient (DeltaCcl-2) mice were studied. Mice received single or combined subretinal injections of cultured retinal pigment epithelium (RPE; C57BL/6-derived), polystyrene microbeads, or phosphate buffer solution (PBS). Fluorescence angiograms were performed over a period of 3 weeks. Mice were euthanized on post inoculation day 3, 7, 10, 14, or 21, and their eyes were evaluated by light, confocal, and electron microscopy.CNV membranes occurred in all study groups with an overall incidence of 94.3%. They extended in the subretinal space through central breaks in Bruch's membrane. CNV lesions were characterized by dynamic changes such as initiation, active inflammatory, and involution stages. CNV thickness peaked around PI day 7 and was greater in mice that received combined injections of RPE and microbeads or RPE cells alone. Small lesions developed in the control groups (microbeads or PBS only), in DeltaCcl-2, and old C57BL/6 mice. Variable expression of cytokines and growth factors was detected within the membranes.Our murine model represents a reliable approach inducing CNV growth by subretinal injection of either RPE cells alone or RPE cells and microbeads. The development of CNV lesions is a dynamic process that relies in part on macrophage trafficking and age.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple