Human pancreatic lipase

Several studies have been conducted on calcium-fat interactions in human infants (64-70). Low synthesis of bile salts and low pancreatic lipase activity may be responsible for poorer fat utilization in infants than in adults (63,71). Fat from infant formulas may be lower than that from human milk because of the lack of a bile-stimulated lipase in the former (72). In infants, fat absorption tends to decrease with increase in fatty acid length, with lower degree of saturation, and with increase of total fat (3). Triglyceride structure may also influence fat absorption in the infant and, thus, indirectly, might also affect calcium absorption in the infant. 

A further group of AT-[(acyloxy)methyl] pro-moieties contains acidic and/or lipid-like substituents. Here again, most published results concern phenytoin. Thus, some phenytoin-lipid conjugates such as 8.183 and 8.186 (with R = various fatty acyl moieties) were reported [233]. Such prodrugs are, of course, insoluble in water but formed dispersions when briefly sonicated in EtOH/water mixtures containing sodium taurodeoxycholate. No significant hydrolysis was seen in buffer or plasma. In contrast, incubation with pancreatic lipase yielded the bis-deacyl derivatives (i.e., 8.182 and 8.185, respectively), with subsequent liberation of phenytoin the time for 50% liberation of phenytoin varied from 20 to 200 min under the conditions of the studies [233][234], The intermediates 8.182, 8.184, and 8.185 were also substrates for human and rat plasma hydrolases. 

Selected entries from Methods in Enzymology [vol, page(s)] Detergent-resistant phospholipase Ai from Escherichia coll membranes, 197, 309 phospholipase Ai activity of guinea pig pancreatic lipase, 197, 316 purification of rat kidney lysosomal phospholipase Ai, 197, 325 purification and substrate specificity of rat hepatic lipase, 197, 331 human postheparin plasma lipoprotein lipase and hepatic triglyceride lipase, 197, 339 phospholipase activity of milk lipoprotein lipase, 197, 345. 

Human pancreatic lipase Seri 52 Leul53 Phe77 ... 

Hydrolases, which catalyze the hydrolysis of various bonds. The best-known subcategory of hydrolases are the lipases, which hydrolyze ester bonds. In the example of human pancreatic lipase, which is the main enzyme responsible for breaking down fats in the human digestive system, a lipase acts to convert triglyceride substrates found in oils from food to monoglycerides and free fatty acids. In the chemical industry, lipases are also used, for instance, to catalyze the —C N —CONH2 reaction, for the synthesis of acrylamide from acrylonitril, or nicotinic acid from 3-pyridylnitrile. 

In another set of studies, it has been reported that the in vitro digestibility of lipid droplets by pancreatic lipase is significantly affected by emulsifier type (Mun et al, 2006, 2007 Park et al., 2007). Intuitively, one might expect that a thick dense layer of strongly bound protein-polysaccharide complex at the oil-water interface would reduce considerably the in vivo accessibility of lipases, and hence would reduce the rate of human metabolism of fats. Establishment of the validity of this hypothesis must still await consolidation of a substantial body of detailed results from independent systematic studies on a broad range of mixed biopolymer systems. 

In addition to LPL, human milk contains a bile salts-activated lipase, which probably contributes to the metabolism of lipids by breast-fed babies who have limited pancreatic lipase activity. Bovine milk and milks from other dairy animals do not contain this enzyme. 

Patton, J.S. and Carey, M.C. 1981. Inhibition of human pancreatic lipase-colipase activity by mixed bile salt-phospholipid micelles. Am. J. Physiol. 241, G328-G336. 

The three dimensional structures of human pancreatic Lipase and Rhizo-mucor miehei lipase have recently been elucidated 1141-1431. Among the lipases purified foam different sources—mammals, bacteria, fungi, and plants-—the fungal lipases from Rhizopuj species exhibit a remarkably broad pH zone of stability and activity, extending from pH 3 to 9. 

As illustrated in Figure 2, human pancreatic lipase consists of two domains. The larger N-terminal domain, a mixed 0E,P-stmcture, comprises residues 1-335 and contains the catalytic triad and a calcium-banding site. The smaller C-terminal domain is formed by two layers of antiparallel -strands and presents a binding site for colipase. 

K. Winkler, A. DfArcy, and W. Hunzlker. Structure of human pancreatic lipase. Aferure 343 771 (1990). 

M. UndsttOm, B. Stentby, and B. BotgstrtJrn. Conceited notion of human carboxyl ester lipase and pancreatic lipase during lipid digestion In vitro Impair-... 

L. Biadcbeig, O. Hemell, and T. Olivecrona. Hydrolysis of human milk fit globules by pancreatic lipase 7. Ctin, Invest. 67 1741 (I9BIX... 

Perez de la Cruz Moreno M, Oth M, Deferme S, Lammert F, Tack J, Dressman J and Augustijns P (2006) Characterization of fasted-state human intestinal fluids collected from duodenum and jejunum. J Pharm Pharmacol 58(8) 1079-1089 Reboul E, Berton A, Moussa M, Kreuzer C, Crenon I and Borel P (2006) Pancreatic lipase and pancreatic lipase-related protein 2, but not pancreatic lipase-related protein 1, hydrolyze retinyl palmitate in physiological conditions. Biochim Biophys Acta 1761(1 ) 4—10 Scheele G, Bartelt D and Biegzr W (1981) Characterisation of human exocrine pancreatic proteins. Gastroent 80(3) 461 473... 

Triglycerides are hydrolyzable into their component fatty adds and glycerol. They are espedally susceptible to alkaline hydrolysis. If KOH or NaOH is used, the process is saponification and the products, sodium and potassium salts of fatty adds, are called soaps. In the human organism, triglycerides are hydrolyzed by various esterases called lipases. These enzymes are quite spedfic, and they do not necessarily remove all three fatty add molecules from a triglyceride molecule. Thus, pancreatic lipase, the main lipid digestive enzyme of the small intestine, catalyzes the removal of fatty acids from positions 1 and 3 only. 

Blackberg, L, Hernell, O., Olivecrona, T. 1981a. Hydrolysis of human milk fat globules by pancreatic lipase. J. Clin. Invest. 67, 1748-1752. 

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