Comparing the Three Hydrolases
You have had the opportunity to investigate three different proteins within the same enzymatic class. These three enzymes have under 20% homology between them, with 14.6% as the high and 9.0% as the low. The cellular location for the enzymes ranged from the cytoplasm to the nucleus of the cell. The function each enzyme has is very specific even though they reside in the same class. They also differ based on their topologies. This includes mainly beta, mainly alpha, alpha and beta and alpha-beta-alpha sandwiches. In addition, they all catalyze bond breaking reactions. However, the bond is at different places or within completely different molecules. Human beta tryptase and human aminopeptidase-2 break peptides bonds, but at different residues, where human uracil-DNA glycosylase breaks a glycosylic bond between a modified base and a sugar. Even though they are all performing the same basic reaction, they use very different catalytic mechanisms. Beta tryptase uses three very specific residues within its active site, where on the other hand, aminopeptidase-2 uses several residues to complete its reaction. As for the glycosylase, it under goes a conformational change that forms its active site. When you take an in-depth look in to this enzyme class, it appears that all of they enzymes are different. The reason they have all been grouped together is because they use the same overall mechanism to cleave bonds. They rely on a water molecule to break the bond into two parts. So in reality, these enzymes are in a world of "Hydrolase Havoc."