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Combining Medium Effects and Cofactor Catalysis: Metal‐Coordinated Synzymes Accelerate Phosphate Transfer by 10 8
Author(s) -
Avenier Frédéric,
Hollfelder Florian
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802616
Subject(s) - chemistry , catalysis , transesterification , enzyme kinetics , phosphate , kinetics , metal , nuclear chemistry , medicinal chemistry , stereochemistry , inorganic chemistry , organic chemistry , active site , physics , quantum mechanics
The systematic exploration of the modification of polyethylene imine with guanidinium and octyl groups has led to the identification of a catalyst, CD6, which accelerates the phosphate transfer reaction of HPNP (2‐hydroxypropyl‐4‐nitrophenyl phosphate) in the presence of divalent metals such as Zn 2+ , Co 2+ , Mg 2+ or Ni 2+ . CD6 exhibits saturation kinetics that are described by Michaelis–Menten parameters K m ranging from 2.5–8 m M and k cat ranging from 0.0014–0.09 s −1 . For Zn II –CD6 this corresponds to an overall acceleration k cat / k uncat of 3.8×10 5 and a catalytic proficiency ( k cat / K m )/ k uncat of 1.5×10 8 . Catalysis by Zn II –CD6 is specifically inhibited by inorganic phosphate, allowing turnover regulation by product inhibition. This effect stands in contrast to Zn II ‐catalysed transesterification of HPNP in water or by the synzymes Co II –CD6 and Ni II –CD6, with which no such interference by product is observed. These characteristics render synzyme Zn II –CD6 an efficient enzyme model that reflects enzyme‐like properties in a wide range of features.