User:Amy Kerzmann/Sandbox 5

== '''Serine Proteases''' ==

== '''Serine Proteases''' ==

Serine proteases account for over one-third of all known proteolytic enzymes <ref>PMID:17991683</ref>,<ref name="DiCera">PMID:19180666</ref>. Within the diverse collection of serine proteases, the most famous members are trypsin, chymotrypsin and elastase. Aside from their key roles in digestion (and other physiological processes) <ref name ="DiCera"/>, the unique specificities of these enzymes make them useful tools in biochemistry and molecular biology to ascertain protein sequences. More information about utilizing proteases for research can be found on the [http://www.expasy.org/ ExPASy Proteomics Server] under the [http://www.expasy.org/tools/peptidecutter/peptidecutter_enzymes.html PeptideCutter Tool].

Serine proteases account for over one-third of all known proteolytic enzymes <ref>PMID:17991683</ref>,<ref name="DiCera">PMID:19180666</ref>. Within the diverse collection of serine proteases, the most famous members are trypsin, chymotrypsin and elastase. Aside from their key roles in digestion (and other physiological processes) <ref name ="DiCera"/>, the unique specificities of these enzymes make them useful tools in biochemistry and molecular biology to ascertain protein sequences. More information about utilizing proteases for research can be found on the [http://www.expasy.org/ ExPASy Proteomics Server] under the [http://www.expasy.org/tools/peptidecutter/peptidecutter_enzymes.html PeptideCutter Tool].

Looking at the structures below, it is apparent that these three enzymes have similar folds. This conservation of tertiary structure is due to extensive similarities at the level of primary amino acid sequence. However, there are small differences in amino acid sequence among the proteins, which are reflected in their different specificities. Each protein cleaves the peptide backbone after (or on the carbonyl side) of a specific type of sidechain; chymotrypsin prefers to cut after aromatic residues, trypsin after basic residues and elastase after smaller neutral residues. After examining the molecular basis for these functional similarities and differences, you will hopefully see why serine proteases are a classic example of how '''''structure dictates function'''''!

Looking at the structures below, it is apparent that these three enzymes have similar folds. This conservation of tertiary structure is due to extensive similarities at the level of primary amino acid sequence. However, there are small differences in amino acid sequence among the proteins, which are reflected in their different specificities. Each protein cleaves the peptide backbone after (or on the carbonyl side) of a specific type of sidechain; chymotrypsin prefers to cut after aromatic residues, trypsin after basic residues and elastase after smaller neutral residues. After examining the molecular basis for these functional similarities and differences, you will hopefully see why serine proteases are a classic example of how '''''structure dictates function'''''!