ABSTRACT
Triacylglycerols consist of three fatty acid chains esterified to a glycerol backbone. Simple triacylglycerols have three identical fatty acids, mixed triacylglycerols have two or three different fatty acids. Triacylglycerols are the major energy store and the major dietary lipid in humans. They are insoluble in water and are stored in specialized adipose cells. Triacylglycerols are synthesized from fatty acyl CoAs and glycerol 3-phosphate. The initial event in the utilization of both stored fat and dietary fat as energy sources is the hydrolysis of triacylglycerol by lipases. The breakdown of fatty acids in ß-oxidation is controlled mainly by the concentration of free fatty acids in the blood, which is, in turn, controlled by the hydrolysis rate of triacylglycerols in adipose tissue by hormone-sensitive triacylglycerol lipase. The anabolic hormone insulin has the opposite effect to glucagon and epinephrine. It stimulates the formation of triacylglycerols through decreasing the level of cAMP, which promotes the dephosphorylation and inactivation of hormone-sensitive lipase.
