An Esterase is a subclass of the hydrolase superfamily for enzymes. There are eight major families and the biological classification has helped determine the properties of these particular enzymes. The different esterases actually vary through their substrate specificity as well as particular protein structures and their function in the body.
There are various esterases. One is the Glucuronoyl esterases, that have recently been discovered and are assumed to have a crucial role to play in the dissociation of cellulose and hemicellulose from lignin. This mechanism occurs through the cleaving of certain ester bonds that exist connecting the aromatic alcohols.
Other studies have highlighted that this is a novel conserved amino acid sequence G-C-S-R-X-G. This features a particular serine residue which is involved with the mechanism of this particular substrate of the esterase family.
Esterases are grouped based on their interaction with crucial organophosphates that are toxicological. These are A-, B- as well as C- esterases. It’s worth pointing out that c- esterases to do not interact with organophosphates at all.
Some studies have explored the esterase activity as well as the conformation changes that occur between the bovine serum albumin and the interaction with mephedrone. The study suggested that the binding mechanism was completely entropic driven. Furthermore, the research also concluded that the forces are hydrophobic.
According to studies psychrophilic organisms that live in a cold environment where the climate does not fluctuate produce enzymes. These are adapted to function and show high catalytic efficiency through low temperatures. This can be explained by two factors. One is the reduction in enthalpy with these enzymes. This is due to the diminished number of protein-ligand interactions. It ensures substrate-binding as well as product release with a low energy barrier at lower temperatures. Secondly, there is an entropy contrast between the enzyme-substrate complex and the apo-enzyme. This is due to the flexibility in confirmation during the substrate binding process.
Studies have also suggested that the b6-a4 loop region of the enzyme could be crucial for controlled ligand recognition. It may also function as a substrate filter which is selective. Another research study highlighted that the enzyme displayed various levels of activity towards certain substrates with an exception to p-NDo.
There have been several crystal structures of microbial esterases that have recently been described. This includes the Bacillus subtilis strain 168, Rhodopeseudomonas paulustris and B. subsites Thai I-8. Based on new studies esterases have an a/b hydrolase fold that is canonical. This is made up of a central b-sheet which is surrounded by a-helices. Furthermore, the active site contains a catalytic triad. That is formed by Ser-Asp-His residues. It’s found in various other serine proteases and esterases.
Indeed, the crystal structure of esterase is complex with a peravetate molecule. This suggests that it could have perhydrolase activity. It is also possible that perhydrolysis could be a side activity from lipases and esterases. One study found that there was significant perhdrolysis activity with a 0.24 ± 0.01 s-1 k value. This is considered to be substantially higher than wild esterases.