Pancreatic lipase hydrolysis, glyceride

Figure 10-3 The Course of Pancreatic Lipase Hydrolysis of Tricaprylin. MG = monoglycerides, DG = diglycerides, TG = triglycerides. Source. From A. Boudreau and J.M. deMan, The Mode of Action of Pancreatic Lipase on Milkfat Glycerides, Can. J. Biochem., Vol. 43, pp. 1799-1805, 1965.

Glowacz et al. (1996) Batch Hydrolysis of triolein and its partial glycerides Porcine pancreatic lipase... 

Ransac, S., Rogalska, E., Gargouri, Y., Deveer, A. M. T. J., Paltauf, F., De Haas, G. H., and Verger, R. 1990. Stereoselectivity of lipases I. Hydrolysis of enantiomeric glyceride analogues by gastric and pancreatic lipases, a kinetic study using the monomolecular film technique. J. Biol. Chem., 265, 20263-20270. 

Several studies have been made on the effect of fatty acid chain length on the rate of hydrolysis of triglycerides. There is fairly general agreement that short-chain glycerides are hydrolyzed at the maximum rate. Most workers find a maximum rate of hydrolysis with tripropionin or tributyrin as substrate. Relative velocities are summarized for pancreatic lipase in Table II. 

Pfluger (1901), put forward the hypothesis that the complete hydrolysis of glycerides by pancreatic lipase was an essential step in triglyceride absorption. The lipolytic theory , was further advanced by Verzar and McDougal (1936), who also demonstrated the hydrotropic action of bile salts, which causes the solubilization of fatty acids and enables them to cross the intestinal barrier. This theory requires also the resynthesis of the triglycerides in the intestinal cells, to... 

An enzyme which catalyses the hydrolysis of glycerides int( glycerol and fatty acids. Several types of lipase may be present ii normal plasma, including pancreatic lipase and lipoproteii lipase. Increased serum levels are found in acute pancreatitis ii much the same way as serum amylase. 

The bile-salt-dependent lipase of pancreatic juice has many names such as cholesterol esterase, nonspecific lipase, the most rational being carboxyl ester lipase [27], In the case of water-insoluble substrates this enzyme has an absolute requirement for bile salts specifically having hydroxyl groups in the 3a and la positions [28.29]. The best documented role for this enzyme is to allow the absorption of dietary cholesterol, through hydrolysis of cholesterol esters in the lumen. The enzyme also catalyzes the esterification of cholesterol and a role for it has been proposed in cholesterol absorption [30]. In addition, a wide range of primary and secondary fatty acyl esters including glycerides, vitamin A and E esters are hydrolyzed by this enzyme. 

Hydrolysis of esterified lipids is essential in order for lipid absorption to occur. Anatomically, lipolysis begins in the stomach where a limited amount of partial hydrolysis of triglycerides provides more polar lipids (fatty acids and partial glycerides) to assist in emulsification. A lingual lipase is thought to be involved in this process. The net result of this gastric phase of fat digestion is the initiation of lipolysis and the preparation of a stable emulsion on which the major pancreatic lipolytic enzymes can act in the milieu of the small intestine. 

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