Factor VIIa: Difference between revisions
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===="His Flip" mechanism==== | ===="His Flip" mechanism==== | ||
This mechanism argues that the protonation of the substrate leaving group by His193 is equally favorable as re-protonation of Ser344 and regeneration of substrate. In order to prevent regeneration of the substrate, His193-H+ flips placing the Nδ1 proton near the leaving group. The argument against this mechanims is the need of disruption and reformation of many hydrogen bonds which seems unlikely in the short lifetime of the transition state. Additionally the principle of loss of motion would be violated<ref>PMID:3542033 </ref><ref>PMID:11170405</ref>. | This mechanism argues that the protonation of the substrate leaving group by His193 is equally favorable as re-protonation of Ser344 and regeneration of substrate. In order to prevent regeneration of the substrate, His193-H+ flips placing the Nδ1 proton near the leaving group. The argument against this mechanims is the need of disruption and reformation of many hydrogen bonds which seems unlikely in the short lifetime of the transition state. Additionally the principle of loss of motion would be violated<ref>PMID:3542033 </ref><ref>PMID:11170405</ref>. | ||
[[Image:his flip.jpg|center]] | |||