EstB is an esterase from Burkholderia gladioli whose physiological function is the hydrolysis of an N5-acyl-L-ornithine ester with moderate S-enantioselectivity.
It is also known to act on short-chain (C4-C6) fatty acid esters and triglycerides, including tertiary alcohol esters (e.g. linalyl acetate). It also shows activity on p-nitrophenyl esters is generally higher than on o-nitrophenyl esters. The Burkholderia gladioli protein is known to be strongly inhibited by eserin, NaF, HgCl2, SDS and Triton X-100.
The primary structure exhibits homology to esterases from family VIII, which are related to class C beta-lactamases. However, catalytic activity is located within the 'beta-lactamase' motif and not the 'esterase' motif. Despite structural similarity with peptidases and class C beta-lactamases, EstB shows no activity with peptides or beta-lactamases.
Defined by 10 residues: SER:A-75LYS:A-78TYR:A-133LEU:A-135ILE:A-152TYR:A-181ASP:A-186HIS:A-253TRP:A-348VAL:A-351