Metal ion induced allosteric transition in the catalytic activity of an artificial phosphodiesterase.
An artificial phosphodiesterase () bearing two types of metal binding sites, a catalytic site and a regulatory bipyridine site showed a unique allosteric transition in the catalytic activity against the metal concentration. The rate constants for the hydrolysis reaction of 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) and RNA dimer (ApA) with and without an effector metal ion were evaluated; the k(obs) value of HPNP hydrolysis for .(Zn(2+))(3) (2.0 x 10(-4) s(-1)) is 3.3 times larger than that for .(Zn(2+))(2). In the case of and Cu(2+), a 19.4 times larger k(obs) value was obtained for .(Cu(2+))(3) (1.2 x 10(-3) s(-1)) against .(Cu(2+))(2). The increase in the catalytic activity is ascribed to the allosteric conformational transition of induced by the coordination of effector metal ion to the Bpy moiety. A detailed investigation revealed that a conformational change of induced by the third M(2+) complexation enhances the rate of hydrolysis rather than a change in the substrate affinity.
Takebayashi
Shinji
S
Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka, 819-0395, Japan. seijitcm@mbox.nc.kyushu-u.ac.jp.
Shinkai
Seiji
S
Ikeda
Masato
M
Takeuchi
Masayuki
M
D000494:Allosteric Regulation / Q000187:drug effects; D002384:Catalysis / Q000187:drug effects; D003300:Copper / Q000737:chemistry / Q000494:pharmacology; D006868:Hydrolysis / Q000187:drug effects; D007700:Kinetics; D008670:Metals / Q000737:chemistry / Q000494:pharmacology*; D009711:Nucleotides / Q000737:chemistry; D010755:Organophosphates; D009943:Organophosphorus Compounds / Q000737:chemistry; D010727:Phosphoric Diester Hydrolases / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D012313:RNA / Q000737:chemistry; D015032:Zinc / Q000737:chemistry / Q000494:pharmacology
C436487:2-(hydroxypropyl)-4-nitrophenyl phosphate; D008670:Metals; D009711:Nucleotides; D010755:Organophosphates; D009943:Organophosphorus Compounds; D012313:RNA; D003300:Copper; D010727:Phosphoric Diester Hydrolases; D015032:Zinc