Combining medium effects and cofactor catalysis: metal-coordinated synzymes accelerate phosphate transfer by 10(8).
Chemistry
; 15(45): 12371-80, 2009 Nov 16.
Article
in En
| MEDLINE
| ID: mdl-19798717
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 3.8x10(5) and a catalytic proficiency (k(cat)/K(m))/k(uncat) of 1.5x10(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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Paraoxon
/
Phosphates
/
Polyethylenes
/
Enzymes
/
Metals
Type of study:
Prognostic_studies
Language:
En
Journal:
Chemistry
Journal subject:
QUIMICA
Year:
2009
Document type:
Article
Affiliation country:
United kingdom