Abstract
Thermophilic and hyperthermophilic carboxylesterases (EC 3.1.1.1) are excellent model systems for studying structure function relationships as well as in vitro and in vivo evolution and possible biotechnological applications. In this paper we review the main aspect of one of most studied microbial representative of the hormone sensitive lipase family (HSL), namely carboxylesterase 2 (EST2) from Alicyclobacillus acidocaldarius.