title: Enzymatic and structural characterization of type II isopentenyl diphosphate isomerase from hyperthermophilic archaeon Thermococcus kodakaraensis.
abstract: Enzymatic and thermodynamic characteristics of type II isopentenyl diphosphate (IPP):dimethylallyl diphosphate (DMAPP) isomerase (Tk-IDI) from Thermococcus kodakaraensis, which catalyzes the interconversion of IPP and DMAPP, were examined. FMN was tightly bound to Tk-IDI, and the enzyme required NADPH and Mg2+ for the isomerization in both directions. The melting temperature (Tm), the change of enthalpy (deltaH(m)), and the heat capacity change (deltaC(p)) of Tk-IDI were 88.0 degrees C, 444 kJ mol(-1), and 13.2 kJ mol(-1) K(-1), respectively, indicating that Tk-IDI is fairly thermostable. Kinetic parameters dramatically changed when the temperature crossed 80 degrees C even though its native overall structure was stably maintained up to 90 degrees C, suggesting that local conformational change would occur around 80 degrees C. This speculation was supported by the result of the circular dichroism analysis that showed the shift of the alpha-helical content occurred at 80 degrees C.
authors.affiliation: Department of Bioscience, Nanobiotechnology Research Center, School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen Sanda, Hyogo 669-1337, Japan.
authors.forename: Masood Ahmed
authors.initials: MA
authors.lastname: Siddiqui
authors.forename: Aiko
authors.initials: A
authors.lastname: Yamanaka
authors.forename: Kazutake
authors.initials: K
authors.lastname: Hirooka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Bamaba
authors.forename: Akio
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Imanaka
authors.forename: Ei-ichiro
authors.initials: E
authors.lastname: Fukusaki
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Fujiwara
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D019748:Carbon-Carbon Double Bond Isomerases / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006358:Hot Temperature; D007700:Kinetics; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D019712:Thermococcus / Q000201:enzymology*; D013816:Thermodynamics
chemical_list: D017931:DNA Primers; D019748:Carbon-Carbon Double Bond Isomerases