Elementary plant Biochemistry and Biotechnology (2+1)

Lipases

• Triacylglycerols or triglycerides undergo hydrolysis by lipases to form glycerol and fatty acids, which undergo further oxidation generating energy.
• Lipases have been reported to be present in dry seeds of some species, e.g. castor bean, Scots pine and Douglas fir but at a low level, or absent in others e.g. apple.
• In most cases of seeds, following imbibitions, there appears to be a rise in lipase activity but whether this increase is due to the de novo synthesis of the enzyme or activation of existing lipases has not been determined.
• A decline in lipase activity is always associated with decline in acylglycerol reserves.
• In castor bean, as in many other fat storing seeds, free fatty acids do not accumulate, but are rapidly degraded and converted to carbohydrate within the endosperm.
• In other seeds such as germinating seeds of oil palm (Elaeis guineensis), a different pattern of fat mobilization can be observed.
• The products of lipid catabolism are transported via specialized structures called haustorium through its vascular system.
• Lipases are generally non specific and can hydrolyse a wide variety of triacylglycerols.
• They initiate digestion by hydrolyzing triacylglycerols to form free fatty acids and 1,2 diacylglycerols.
• Complete hydrolysis of triacylglycerols produces glycerol and fatty acids.Lipase hydrolyses easily the terminal fatty acids to produce 2 monoacyl glycerol as major