CYP3A4: Difference between revisions

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Because water molecules are stripped away when the substrate binds, this causes an entropy change of 26 kcal/mol. This entropy driven reaction has a spontaneous free energy change of -7.7 at 21ºC <ref name="Dai">PMID: 15352783</ref>.

The cycle begins with the binding of the substrate to the ferric heme. With the addition of an electron, the heme gets reduced. This can only happen once the substrate is bound because the reduction potential is -300V while in that state and is more electronegative. After substrate binding, the induced conformational shift causes the reduction potential to be more positive at -230V making this a more thermodynamically favorable reaction. Oxygen next binds to the heme and oxidizes it. The addition of a second electron cleaves the oxygen-oxygen bond allowing one atom to bind two hydrogens producing water and the second oxygen joins the substrate in what is called a monoxygenation reaction.

The cycle begins with the binding of the substrate to the ferric heme. With the addition of an electron, the heme gets reduced. This can only happen once the substrate is bound because the reduction potential is -300V while in that state and is more electronegative. After substrate binding, the induced conformational shift causes the reduction potential to be more positive at -230V making this a more thermodynamically favorable reaction. Oxygen next binds to the heme and oxidizes it. The addition of a second electron cleaves the oxygen-oxygen bond allowing one atom to bind two hydrogens producing water and the second oxygen joins the substrate in what is called a monoxygenation reaction <ref> Devlin, Thomas M., ed. Textbook of Biochemistry with Clinical Correlations. 6th ed. Hoboken: John Wiley, 2006. Print.</ref>

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 Because water molecules are stripped away when the substrate binds, this causes an entropy change of 26 kcal/mol.  This entropy driven reaction has a spontaneous free energy change of -7.7 at 21ºC <ref name="Dai">PMID: 15352783</ref>.
-The cycle begins with the binding of the substrate to the ferric heme.  With the addition of an electron, the heme gets reduced. This can only happen once the substrate is bound because the reduction potential is -300V while in that state and is more electronegative. After substrate binding, the induced conformational shift causes the reduction potential to be more positive at -230V making this a more thermodynamically favorable reaction.  Oxygen next binds to the heme and oxidizes it. The addition of a second electron cleaves the oxygen-oxygen bond allowing one atom to bind two hydrogens producing water and the second oxygen joins the substrate in what is called a monoxygenation reaction.
+The cycle begins with the binding of the substrate to the ferric heme.  With the addition of an electron, the heme gets reduced. This can only happen once the substrate is bound because the reduction potential is -300V while in that state and is more electronegative. After substrate binding, the induced conformational shift causes the reduction potential to be more positive at -230V making this a more thermodynamically favorable reaction.  Oxygen next binds to the heme and oxidizes it. The addition of a second electron cleaves the oxygen-oxygen bond allowing one atom to bind two hydrogens producing water and the second oxygen joins the substrate in what is called a monoxygenation reaction  <ref> Devlin, Thomas M., ed. Textbook of Biochemistry with Clinical Correlations. 6th ed. Hoboken: John Wiley, 2006. Print.</ref>
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