title: Kinetic analyses of divalent cation-dependent EcoRV digestions on a DNA-immobilized quartz crystal microbalance.
abstract: Enzymatic digestion with a type IIP restriction endonuclease EcoRV was investigated on a DNA-immobilized 27-MHz quartz crystal microbalance (QCM). Real-time observations of both the enzyme binding process and the DNA cleavage process of EcoRV were followed by frequency (mass) changes on the QCM, which were dependent on divalent cations such as Ca(2+) or Mg(2+). In the presence of Ca(2+), the site-specific binding of EcoRV to DNA could be observed, without the catalytic process. On the other hand, in the presence of Mg(2+), both the binding of the enzyme to the specific DNA (mass increase) and the site-specific cleavage reaction (mass decrease) could be observed continuously from QCM frequency changes. From time courses of frequency (mass) changes, each kinetic parameter, namely binding rate constants (k(on)), dissociation rate constants (k(off)), dissociation constants (K(d)) of EcoRV to DNA, and catalytic rate constant (k(cat)) of the cleavage reaction, could be determined. The binding kinetic parameters of EcoRV in the presence of Ca(2+) were consistent with those of the binding process followed by the cleavage process in the presence of Mg(2+). The k(cat) value obtained by the QCM method was also consistent with that obtained by other methods. This study is the first to simultaneously determine k(on), k(off), and k(cat) for a type IIP restriction endonuclease on one device.
authors.affiliation: Department of Biomolecular Engineering, Frontier Collaborative Research Center, Tokyo Institute of Technology and CREST, Japan Science and Technology Corp., 4259 Nagatsuta, Yokohama 226-8501, Japan.
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Takahashi
authors.forename: Hisao
authors.initials: H
authors.lastname: Matsuno
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Furusawa
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Okahata
mesh_terms: D000595:Amino Acid Sequence; D001710:Biotin / Q000737:chemistry; D002118:Calcium / Q000737:chemistry*; D002384:Catalysis / Q000187:drug effects; D002413:Cations, Divalent / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D053837:DNA Cleavage; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry*; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry*; D008969:Molecular Sequence Data; D011791:Quartz / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D011791:Quartz; D001710:Biotin; D004247:DNA; D015252:Deoxyribonucleases, Type II Site-Specific; C027440:GATATC-specific type II deoxyribonucleases; D008274:Magnesium; D002118:Calcium