The different roles of metal ions and water molecules in the recognition and catalyzed hydrolysis of ATP by phenanthroline-containing polyamines.
The phenanthroline bridging polyaza ligands L1, L2 and L3 can selectively and strongly bind nucleotides at physiological pH, and hence accelerate the hydrolysis rate of the bound ATP. It is interesting that a phosphoramidate intermediate at 2.88 ppm (should be added 5.63 ppm when compared with other models) was found in the hydrolysis process of L/ATP. By introduction of metal ions (critical Zn(2+) or hard Mg(2+), Ca(2+)) to the L/ATP system, recognition of the anionic substrates by the protonated ligands was greatly promoted. However, due to the different affinities of metal ions to the receptor and the substrate, ATP hydrolysis in Zn(2+)/L/ATP system and Mg(2+)(Ca(2+))/L/ATP system occurs through different mechanisms. By comparison with the M/ATP (M=Zn(2+), Mg(2+), Ca(2+)) system, the rates of ATP-hydrolysis in the Mg(2+)Ca(2+)/L/ATP system and the Zn(2+)/L/ATP system were enhanced and retarded, respectively. Moreover, the reasons contributing to large rate range of the L/ATP systems and M(2+)/L/ATP systems were given. The results show that metal ions vertically regulate the recognition and hydrolysis of ATP. On the other hand, water molecule participates in the hydrolysis reactions at different steps with different functions in the L/ATP systems and M(Zn(2+), Mg(2+), Ca(2+))L/ATP systems.
Guo
Yanhe
Y
Department of Chemistry, Nankai University, Tianjin 300071, PR China.
Ge
Qingchun
Q
Lin
Hai
H
Lin
Hua Kuan
HK
Zhu
Shourong
S
Zhou
Changyue
C
D000244:Adenosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000737:chemistry; D002384:Catalysis; D002413:Cations, Divalent / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010618:Phenanthrolines / Q000737:chemistry*; D011073:Polyamines / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D011522:Protons; D013696:Temperature; D014867:Water / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
D002413:Cations, Divalent; D008670:Metals; D010618:Phenanthrolines; D011073:Polyamines; D011522:Protons; D014867:Water; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008274:Magnesium; D015032:Zinc; D002118:Calcium