The wax esters of fish and of jojoba seed oils are poorly hydrolysed by the pancreatic lipases of the human digestive system so that these lipids have poor nutritive value for man. Fish, such as salmon and herring grow rapidly when feeding on zooplankton rich in wax esters, yet do not contain these lipids themselves. Their digestive systems are adapted to the efficient hydrolysis of wax esters, most of the products being absorbed and resyn-thesized into TAG. Tissue breakdown of wax esters so that the products can be utilized as metabolic fuels presumably involves lipases or esterases analogous to the hormone-sensitive lipases in adipose tissue of organisms that store TAG, but these reactions have been little studied.
Some authorities now believe that wax esters have to be considered as key compounds in the transmission of carbon through the marine food chain. Wax esters seem to be found in greatest amounts in regions where animals experience short periods of food plenty followed by long periods of food shortage, for example in polar regions, where
Normal chain length fatty acyl-CoA
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