10.9 Lipases and esterases
Lipases and esterases catalyse the hydrolysis of esters made between alcohols and organic (‘fatty’) acids. They generally have low specificity and any lipase will hydrolyse virtually any organic ester, though different esters will be acted upon at different rates. The main factors influencing what specificity is expressed are the lengths and shape of hydrocarbon chains either side of the ester link. The term esterase is generally applied to enzymes ‘preferring’ short carbon chains in the acyl group. Lipases ‘proper’ tend to favour long carbon chains in the acyl group. Their substrates include fats, the lipid components of lipoprotein and the ester bonds in phospholipids.
Extracellular lipase production has been detected in Agaricus bisporus during degradation of bacteria. In fermenter cultures most of the lipase is produced in the stationary phase (i.e. is a secondary metabolic activity) and regulation of lipase production in Rhizopus is very much affected by carbon and nitrogen sources in the medium and by the oxygen concentration.
Updated December 17, 2016