Steady-state kinetic investigation of cytochrome P450cam: interaction with redox partners and reaction with molecular oxygen.

Biochemistry 2004 Jan;43(1):271-81

Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA.

Cytochrome P450cam (CYP101) is a prokaryotic monooxygenase that requires two proteins, putidaredoxin reductase (PdR) and putidaredoxin (Pdx), to supply electrons from NADH. This study addresses the mechanism by which electrons are transported from PdR to P450cam through Pdx and used to activate O(2) at the heme of P450cam. It is shown that k(cat)/Km(O2) is independent of the PdR concentration and hyperbolically dependent on Pdx. The phenomenon of saturation of reaction rates with either P450cam or PdR at high ratios of one enzyme to the other is investigated and shown to be consistent with a change in the rate limiting step. Either the reduction of Pdx by PdR (high P450) or the reduction of P450 by Pdx (high PdR) determines the rate. These data support a mechanism where Pdx acts as a shuttle for transport of electrons from PdR to P450cam, effectively ruling out the formation of a kinetically significant PdR/Pdx/P450cam complex.

Download full-text PDF

Source
http://dx.doi.org/10.1021/bi0356045DOI Listing
January 2004
4 Reads

Publication Analysis

Top Keywords

pdr high
8
pdr p450cam
8
cytochrome p450cam
8
pdr
7
pdx
6
p450cam
6
support mechanism
4
kcat/kmo2 independent
4
independent pdr
4
rate data
4
data support
4
concentration hyperbolically
4
dependent pdx
4
hyperbolically dependent
4
pdr concentration
4
p450cam kcat/kmo2
4
transported pdr
4
electrons transported
4
high p450
4
mechanism electrons
4

Similar Publications