Fluorogenic indicator

Generally, sensors based on chromogenic or fluorogenic indicators are advantageous over sensors based on PSDs or ion-exchange/co-extraction. A... 

Chen, C. S. Gee, K. R. Redox-dependent trafficking of 2,3,4,5,6-pentafluorodihydrotetramethylrosamine, a novel fluorogenic indicator of cellular oxidative activity. Free Radical Biol. Med. 2000,28,1266-1278. 

Class 2 fluorophores that can reversibly bind an analyte. If the analyte is a proton, the term fluorescent pH indicator is often used. If the analyte is an ion, the term fluorescent chelating agent is appropriate. Fluorescence can be either quenched upon binding (CEQ type Chelation Enhancement of Quenching), or enhanced (CEF type Chelation Enhancement of Fluorescence). In the latter case, the compound is said to be fluorogenic [e.g. 8-hydroxyquinoline (oxine)]. 

Note Reactions were performed under the conditions described in the text with either colorimetric peptide pNA4 (250 pM) or fluorogenic peptide F3 (35 pM) as a substrate. The IC50 values represent the inhibitor concentration required to reduce the protease activity by 50% of the control containing no inhibitor. NI, no inhibition was observed at the concentrations indicated. E64, frans-epoxysuccinyl-L-leucylamide-(4-guanidino)-butane PMSF, phenylmethylsulphonyl fluoride TLCK, tosyl-L-lysine-chloromethyl ketone. 

In recent years, the importance of enzyme levels in body fluids for clinical diagnosis has been recognized. It has been established that activities of secreted enzymes and cellular enzymes in serum are a sensitive indication of the pathophysiological condition of the body. Specific and sensitive substrates play a prominent role for this purpose. Fluorogenic substrates, e.g., enable sensitive micro-analyses. 

MIC. The resulting concentrations were adsorbed on Amberlite XAD-2 and analyzed by desorbing and reacting with fluorescamine and subsequent fluorogenic assay. An average recovery of 101.3 percent was obtained. The excellent recoveries and the small precision statistic indicate that high relative humidities do not significantly effect sample collection and retention of MIC on XAD-2. Table X displays the results. 

The assay is based on the membrane-permeant fluorogenic substrate calcein-AM, which is hydrolyzed by intracellular esterases to yield a green fluorescent product (calcein) which is easily determined by fluorometry (ex/em 495/ 515 nm). Thus, green fluorescence is an indicator of cells that have esterase activity as well as an intact membrane to retain the esterase products. Since different cell lines may have different esterase activity on calcein-AM, a calibration curve should be prepared per each ceU line, in which a known number of cells is correlated to the amount of fluorescence read by the instrument. 

Employing variations of the ELISA technique, the fluorogenic ELISA assays are based on the capture of antigens or antibodies from a solution by an insoluble solid phase. These assays are used to determine concentrations of high molecular weight analytes, to indicate the presence of specific antibodies, or for competitive analysis of low-concentration haptens. A linear capillary... 

Fluorescent derivatives of naltrindole have been prepared. The fluorescent analog in which fluorescein was attached through a tet-raglycine spacer to 7 -amino-NTI has been prepared (339) its fluorescence is blocked by NTI, indicating specific binding to 8 receptors. Recently, a fluorogenic "reporter affinity label" derivative of naltrindole, PNTI, was prepared from 7 -amino-NTI that, in contrast to its reversible counterpart, is an agonist in the MVD (340) (see Section 5.11 below). 

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