Combining Medium Effects and Cofactor Catalysis: Metal-Coordinated Synzymes Accelerate Phosphate Transfer by 108
✍ Scribed by Frédéric Avenier; Florian Hollfelder
- Book ID
- 102795099
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 564 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0947-6539
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
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 mM 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.