ABSTRACT
Triacylglycerols consist of three fatty acid chains esterified to a glycerol backbone. Triacylglycerols constitute the major fuel store and the major dietary lipid in humans. Triacylglycerols are a highly concentrated energy store. Triacylglycerols are synthesized from fatty acyl coenzyme A (CoA) and glycerol 3-phosphate. The glycolytic intermediate dihydroxyacetone phosphate is first reduced to glycerol 3-phosphate which is, in turn, acylated by glycerol-3-phosphate acyltransferase to form lysophosphatidic acid. 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.
