scholarly journals Resolution of Multiple Substrate Binding Sites in Cytochrome P450 3A4:  The Stoichiometry of the Enzyme−Substrate Complexes Probed by FRET and Job's Titration†

Biochemistry ◽  
2006 ◽  
Vol 45 (13) ◽  
pp. 4199-4209 ◽  
Author(s):  
Harshica Fernando ◽  
James R. Halpert ◽  
Dmitri R. Davydov
Keyword(s):  
Cytochrome P450 ◽  
Binding Sites ◽  
Substrate Binding ◽  
Cytochrome P450 3A4 ◽  
Enzyme Substrate ◽  
Multiple Substrate ◽  
Substrate Binding Sites

scholarly journals Multiple substrate-binding sites are retained in cytochrome P450 3A4 mutants with decreased cooperativity

Xenobiotica ◽  
2010 ◽  
Vol 41 (4) ◽  
pp. 281-289 ◽  
Author(s):  
Harshica Fernando ◽  
Jessica A. O. Rumfeldt ◽  
Nadezhda Y. Davydova ◽  
James R. Halpert ◽  
Dmitri R. Davydov
Keyword(s):  
Cytochrome P450 ◽  
Binding Sites ◽  
Substrate Binding ◽  
Cytochrome P450 3A4 ◽  
Multiple Substrate ◽  
Substrate Binding Sites

scholarly journals Sigmoidal kinetic model for two co-operative substrate-binding sites in a cytochrome P450 3A4 active site: an example of the metabolism of diazepam and its derivatives

1999 ◽  
Vol 340 (3) ◽  
pp. 845-853 ◽  
Author(s):  
Magang SHOU ◽  
Qin MEI ◽  
JR. Michael W. ETTORE ◽  
Renke DAI ◽  
Thomas A. BAILLIE ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Kinetic Model ◽  
Binding Affinity ◽  
Active Site ◽  
Binding Sites ◽  
Dissociation Constants ◽  
Substrate Binding ◽  
Cytochrome P450 3A4 ◽  
Multiple Drugs ◽  
Substrate Binding Sites

Cytochrome P450 3A4 (CYP3A4) plays a prominent role in the metabolism of a vast array of drugs and xenobiotics and exhibits broad substrate specificities. Most cytochrome P450-mediated reactions follow simple Michaelis-Menten kinetics. These parameters are widely accepted to predict pharmacokinetic and pharmacodynamic consequences in vivo caused by exposure to one or multiple drugs. However, CYP3A4 in many cases exhibits allosteric (sigmoidal) characteristics that make the Michaelis constants difficult to estimate. In the present study, diazepam, temazepam and nordiazepam were employed as substrates of CYP3A4 to propose a kinetic model. The model hypothesized that CYP3A4 contains two substrate-binding sites in a single active site that are both distinct and co-operative, and the resulting velocity equation had a good fit with the sigmoidal kinetic observations. Therefore, four pairs of the kinetic estimates (KS1, kα, KS2, kβ, KS3, k∆, KS4 and kγ) were resolved to interpret the features of binding affinity and catalytic ability of CYP3A4. Dissociation constants KS1 and KS2 for two single-substrate-bound enzyme molecules (SE and ES) were 3-50-fold greater than KS3 and KS4 for a two-substrate-bound enzyme (SES), while respective rate constants k∆ and kγ were 3-218-fold greater than kα and kβ, implying that access and binding of the first molecule to either site in an active pocket of CYP3A4 can enhance the binding affinity and reaction rate of the vacant site for the second substrate. Thus our results provide some new insights into the co-operative binding of two substrates in the inner portions of an allosteric CYP3A4 active site.

scholarly journals The Tim8–Tim13 Complex Has Multiple Substrate Binding Sites and Binds Cooperatively to Tim23

2008 ◽  
Vol 382 (5) ◽  
pp. 1144-1156 ◽  
Author(s):  
Kristen N. Beverly ◽  
Michael R. Sawaya ◽  
Einhard Schmid ◽  
Carla M. Koehler
Keyword(s):  
Binding Sites ◽  
Substrate Binding ◽  
Multiple Substrate ◽  
Substrate Binding Sites

scholarly journals QM/MM Study of the Active Species of the Human Cytochrome P450 3A4, and the Influence Thereof of the Multiple Substrate Binding

2007 ◽  
Vol 111 (49) ◽  
pp. 13822-13832 ◽  
Author(s):  
Dan Fishelovitch ◽  
Carina Hazan ◽  
Hajime Hirao ◽  
Haim J. Wolfson ◽  
Ruth Nussinov ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Substrate Binding ◽  
Active Species ◽  
Cytochrome P450 3A4 ◽  
Human Cytochrome ◽  
Multiple Substrate
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