Factor VIIa: Difference between revisions

===Evolutionary specificity===

All of the serine proteases have a catalytic domain consisting of two β-barrels with the catalytic triad, Ser-His-Asp located at the interface<ref>PMID:9374470</ref>. Five enzyme-substrate hydrogen bonds at positions P1 and P3 are well conserved and serve to position the scissile peptide bond in the correct orientation for an attack by the γ-oxygen of Ser. More distal contacts diverge. Mutational experiments have shown that the S1 pocket is important in organization of the substrate for catalysis. Divergent evolution[http://en.wikipedia.org/wiki/Divergent_evolution]enabled mammals to possess multiple enzymes with specific roles. Earlier organisms, bacteria and prokaryotes, possess broad specificities of the active site where more distant residues play a bigger role in substrtate recognition<ref>PMID:2716847</ref>. The most divergent are the surface loops which control specificity. Serine proteases not only show the divergence of substrate specificity but also examples of convergent evolution[http://en.wikipedia.org/wiki/Convergent_evolution].  A demonstration of convergent evolution in serine proteases is found in four other folds, besides the chynotrypsin-like fold, with the catalytic triad in similar positions<ref>PMID:879782</ref>.