Assay for glucosamine 6-phosphate using a ligand-activated ribozyme with fluorescence resonance energy transfer or CE-laser-induced fluorescence detection.
A naturally occurring aptazyme, the glmS ribozyme, is adapted to an assay for glucosamine 6-phosphate, an effector molecule for the aptazyme. In the assay, binding of analyte allosterically activates aptazyme to cleave a fluorescently labeled oligonucleotide substrate. The extent of reaction, and hence analyte concentration, is detected by either fluorescence resonance energy transfer (FRET) or capillary electrophoresis with laser-induced fluorescence (CE-LIF). With FRET, assay signal is the rate of increase in FRET in presence of analyte. With CE-LIF, the assay signal is the peak height of cleavage product formed after a fixed incubation time. The assay has a linear response up to 100 (CE-LIF) or 500 microM (FRET) and detection limit of approximately 500 nM for glucosamine 6-phosphate under single-turnover conditions. When substrate is present in excess of the aptazyme, it is possible to amplify the signal by multiple turnovers to achieve a 13-fold improvement in sensitivity and detection limit of 50 nM. Successful signal amplification requires a temperature cycle to alternately dissociate cleaved substrate and allow fresh substrate to bind aptazyme. The results show that aptazymes have potential utility as analytical reagents for quantification of effector molecules.
Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA.
Jennifer R W
JR
Furchak
Peilin
P
Yang
Colin
C
Jennings
Nils G
NG
Walter
Robert T
RT
Kennedy
D001483:Base Sequence; D002138:Calibration; D019075:Electrophoresis, Capillary / Q000379:methods*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D019298:Glucose-6-Phosphate / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D008969:Molecular Sequence Data; D012270:Ribosomes / Q000378:metabolism*
D008024:Ligands; C001293:glucosamine 6-phosphate; D019298:Glucose-6-Phosphate; D005944:Glucosamine