NMR-Derived Models of Amidopyrine and Its Metabolites in Complexes with Rabbit Cytochrome P450 2B4 Reveal a Structural Mechanism of Sequential N-Dealkylation
摘要:
To understand the molecular basis of sequential N-dealkylation by cytochrome P450 2B enzymes, we studied the binding of amidopyrine (AP) as well as the metabolites of this reaction, desmethylamidopyrine (DMAP) and aminoantipyrine (AAP), using the X-ray crystal structure of rabbit P450 2B4 and two nuclear magnetic resonance (NMR) techniques: saturation transfer difference (STD) spectroscopy and longitudinal (T-1) relaxation NMR. Results of STD NMR of AP and its metabolites bound to P450 2B4 were similar, suggesting that they occupy similar niches within the enzyme's active site. The model-dependent relaxation rates (R-M) determined from T-1 relaxation NMR of AP and DMAP suggest that the N-linked methyl is closest to the heme. To determine the orientation(s) of AP and its metabolites within the P450 2B4 active site, we used distances calculated from the relaxation rates to constrain the metabolites to the X-ray crystal structure of P450 2B4. Simulated annealing of the complex revealed that the metabolites do indeed occupy similar hydrophobic pockets within the active site, while the N-linked methyls are free to rotate between two binding modes. From these bound structures, a model of N-demethylation in which the N-linked methyl functional groups rotate between catalytic and noncatalytic positions was developed. This study is the first to provide a structural model of a drug and its metabolites complexed to a c-ytochrome P450 based on NMR and to provide a structural mechanism for how a drug can undergo sequential oxidations without unbinding. The rotation of the amide functional group might represent a common structural mechanism for N-dealkylation reactions for other drugs such as the local anesthetic lidocaine.
An immunoassay element for assaying a target substance in a fluid sample by utilizing homogeneous competitive reaction of the target substance and a labelled substance which is a target substance or an analogue thereof labelled with a marker, with a substance which specifically reacts with both the target substance and the labelled substance. The immunoassay element comprises, in the order mentioned from the top to the bottom, the layers of a) a fibrous porous spreading layer; b) a non-fibrous porous reaction layer comprising the substance which specifically reacts with both the target substance and the labelled substance; and c) a non-porous layer comprising a macromolecular substance in which the labelled substance is incorporated. The labelled substance gives a signal which is changed when the labelled substance is bound to the substance which specifically reacts with both the target substance and the labelled substance.
Analyte concentration detection devices and methods
申请人:Intuity Medical, Inc.
公开号:EP2322914A1
公开(公告)日:2011-05-18
Arrangements for the detection of the presence and/or concentration of an analyte in a sample of bodily fluid include diffuse transmission, diffuse reflection and edge or waveguide illumination arrangements. A vertical flow assay and/or detection component (100) is provided in the form of an array of optical detection elements (24).
NUCLEIC ACID ELEMENT FOR USE IN ANALYSIS, AND ANALYTICAL METHOD, ANALYTICAL REAGENT AND ANALYTICAL INSTRUMENT USING SAME
申请人:NEC Soft, Ltd.
公开号:EP2463660A1
公开(公告)日:2012-06-13
The technique by which simple analysis of an intended subject to be analyzed can be carried out is provided, In this technique, a nucleic acid element 16 for use in analysis including: a first nucleic acid part 12; and a second nucleic acid part 13 is used. In the nucleic acid element 16, the first nucleic acid part 12 is a binding part that can bind to a subject 11 to be analyzed, and the second nucleic acid part 13 is a labeling part that can distinguish between binding and non-binding of the first nucleic acid part 12 to the subject 11. It is preferred that the first nucleic acid part 12 is an aptamer against the subject 11. The subject 11 can be analyzed easily by using the nucleic acid element 16, binding the subject 11 to the first nucleic acid part 12, and then analyzing the binding with the second nucleic acid part 13.
The present invention provides a detection instrument capable of easily detecting an intended detection object without any skilled technique. The detection instrument (1) of the present invention includes a detection portion (12), a detection reagent which develops a color by specifically reacting with a detection object in a sample is placed in the detection portion (12), positional information of the detection reagent in the detection portion (12) is information on the detection object, and color development of the detection reagent can be optically read. It is preferred that a bar code is formed in the detection portion (12), and the detection reagent is placed as a part of the bar code.
The present invention provides a technique capable of simply analyzing a target to be analyzed. An analytical device of the present invention includes a basal plate; a nucleic acid element; and a detection section of detecting a signal. The nucleic acid element and the detection section are arranged on the basal plate. The nucleic acid element includes a first nucleic acid molecule and a second nucleic acid molecule. The first nucleic acid molecule is a nucleic acid molecule capable of binding to a target. The second nucleic acid molecule is a nucleic acid molecule capable of binding to streptavidin. When the target does not bind to the first nucleic acid molecule, a binding capacity of the second nucleic acid molecule to the streptavidin is inactivated. When the target binds to the first nucleic acid molecule, a binding capacity of the second nucleic acid molecule to the streptavidin is activated. The detection section detects binding between the second nucleic acid molecule and the streptavidin. The target is bound to the first nucleic acid molecule, so that the streptavidin is bound to the second nucleic acid molecule. Thus, the target can be analyzed through detecting the binding between the second nucleic acid molecule and the streptavidin using the detection device.