Factor Xa: Difference between revisions
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===General Serine Protease Mechanism=== | ===General Serine Protease Mechanism=== | ||
During the acylation half of the reaction His57 acts as a general base to remove a proton from Ser195, allowing it to attack the carbonyl of the peptide bond to be broken within the substrate, to yield the first tetrahedral intermediate. The negative oxygen ion of the tetrahedral intermediate is stabilized through hydrogen bonding with the oxyanion hole (Gly192 and Ser195). Asp102 stabilizes the protonated His57 through hydrogen bonding. His57 protonates the amine of the scissile bond, promoting formation of the acylenzyme and release of the N-terminal portion of the substrate. | During the acylation half of the reaction His57 acts as a general base to remove a proton from Ser195, allowing it to attack the carbonyl of the peptide bond to be broken within the substrate, to yield the first tetrahedral intermediate. The negative oxygen ion of the tetrahedral intermediate is stabilized through hydrogen bonding with the oxyanion hole (Gly192 and Ser195). Asp102 stabilizes the protonated His57 through hydrogen bonding. His57 protonates the amine of the scissile bond, promoting formation of the acylenzyme and release of the N-terminal portion of the substrate. | ||
The deacylation portion repeats the same sequence. A water molecule is deprotonated by His57 and attacks the acyl enzyme, to yielding a second tetrahedral intermediate. Again, the tetrahedral intermediate is stabilized by the oxyanion hole. Upon collapse of the tetrahedral intermediate, the C-terminal portion of the protein is released.<ref name="specificity">PMID:12475199</ref>[[Image:Serine protease mechanism.gif.png| | The deacylation portion repeats the same sequence. A water molecule is deprotonated by His57 and attacks the acyl enzyme, to yielding a second tetrahedral intermediate. Again, the tetrahedral intermediate is stabilized by the oxyanion hole. Upon collapse of the tetrahedral intermediate, the C-terminal portion of the protein is released.<ref name="specificity">PMID:12475199</ref> | ||
[[Image:Serine protease mechanism.gif.png|400px|center|'''Serine protease reaction mechanism''' <ref> www.bmolchem.wisc.edu/</ref> />]] | |||
===Controversial Mechanisms=== | ===Controversial Mechanisms=== | ||