Lactose Repressor-Operator DNA Interactions: Kinetic Analysis by a Surface Plasmon Resonance Biosensor

摘要: Lactose repressor binding to operator DNA and subsequent dissociation of the complex was monitored continuously by a biosensor, measuring surface plasmon resonance. In this analysis synthetic, double-stranded oligonucleotide containing site immobilized on sensor protein passed over surface. The formation repressor-operator specific could be inhibited isopropyl-β-D-thiogalactopyranoside inducer. From association curve, apparent kass determined 1.8 × 106 M−1 s−1. Dissociation was, for first time lac repressor, as an uncatalyzed reaction kdiss 3.4 10−4 As reference, interaction analyzed electrophoretic mobility shift assay under similar conditions. With method equilibrium constant calculated 2.4(±0.2) 108 M−1. corresponding value from biosensor data 5.1 109