Biochemical and structural comparative study between bird and mammal pancreatic colipases

Fat digestion and metabolism: effect of different fat sources and fat mobilisers in broilers diet on growth performance and physiological parameters – a review

Commercial broilers have a short production cycle and a high requirement for energy (3000 kcal/kg in starter phase and 3200 kcal/kg in finisher phase). Therefore, the need to add energy rich lipids to their diet is inevitable. Digestibility of fat depends on its multiple properties: chain length, the composition of fatty acids, ratio of saturated/unsaturated fatty acids and free fatty acids. The high cost of vegetable oils and less availability due to their consumption in human diet are the main reasons for searching cheaper alternative fat sources. Animal oils like poultry and fish oil are the by-product of rendering plants and after refining, they are used in poultry diets as an energy source. Due to presence of impurities and free fatty acids, the digestibility of animal fat is less. There is a limited amount of bile acids and lipase available during early age and when birds are reared on high energy diet (finisher phase). Supplementation of emusifier or lipase in broilers diet increase fat utilisation. Emulsifiers increase fat digestibility by increasing active surface area of lipid droplets. Lysolecithin and Lysophospholipids are produced from hydrolyses of lecithin and phospholipids by phopholipase A2. The bile acids mainly compose of cholic acid, hyodeoxycholic acid and chenodeoxycholic acid and have strong emulsification properties. Triacylglyceryl acylase (lipase) is an enzyme involved in catalysis and the hydrolysis of lipids. It can be concluded that use of emulsifier and lipase in broilers diet improves growth performance, nutrient digestibility and intestinal histology in broilers.

Helix aspersa gelatin as an emulsifier and emulsion stabilizer: functional properties and effects on pancreatic lipolysis

Emulsions are widely used in food and pharmaceutical applications for the encapsulation, solubilization, entrapment, and controlled delivery of active ingredients.

Phospholipase A2 purification and characterization: a case study

We compared here the purification procedures, the pH, the calcium, the bile salts, and the temperature dependencies as well as the catalytic activities on phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of two purified secreted PLA2 from chicken pancreatic (ChPLA2-IB) and chicken intestinal (ChPLA2-IIA) origins. Interestingly, ChPLA2-IB hydrolyzes efficiently both purified PC and PE, whereas ChPLA2-IIA hydrolyzes only PE and not PC, even after a long incubation period. These analytical results clearly indicate that the catalytic activity of ChPLA2-IIA, measured with the pH-stat and using egg yolk as substrate, is mainly due to the hydrolysis of the PE fraction present in egg yolk.

Biochemical properties of pancreatic colipase from the common stingray Dasyatis pastinaca

BACKGROUND

Pancreatic colipase is a required co-factor for pancreatic lipase, being necessary for its activity during hydrolysis of dietary triglycerides in the presence of bile salts. In the intestine, colipase is cleaved from a precursor molecule, procolipase, through the action of trypsin. This cleavage yields a peptide called enterostatin knoswn, being produced in equimolar proportions to colipase.

RESULTS

In this study, colipase from the common stingray Dasyatis pastinaca (CoSPL) was purified to homogeneity. The purified colipase is not glycosylated and has an apparent molecular mass of around 10 kDa. The NH2-terminal sequencing of purified CoSPL exhibits more than 55% identity with those of mammalian, bird or marine colipases. CoSPL was found to be less effective activator of bird and mammal pancreatic lipases than for the lipase from the same specie. The apparent dissociation constant (Kd) of the colipase/lipase complex and the apparent Vmax of the colipase-activated lipase values were deduced from the linear curves of the Scatchard plots. We concluded that Stingray Pancreatic Lipase (SPL) has higher ability to interact with colipase from the same species than with the mammal or bird ones.

CONCLUSION

The fact that colipase is a universal lipase cofactor might thus be explained by a conservation of the colipase-lipase interaction site. The results obtained in the study may improve our knowledge of marine lipase/colipase.

Proteolytic cleavage of ostrich and turkey pancreatic lipases: production of an active N-terminal domain

OBJECTIVES

The aim of this study was to check some biochemical and structural properties of ostrich and turkey pancreatic lipases (OPL and TPL, respectively).

METHODS

Limited proteolysis of OPL and TPL was performed in conditions similar to those reported for porcine pancreatic lipase.

RESULTS

In the absence of bile salts and colipase, OPL failed to catalyze the hydrolysis of pure tributyrin or efficiently hydrolyze olive oil emulsion. When bile salts and colipase were preincubated with the substrate, the OPL kinetic behavior remained linear for more than 30 minutes. The enzyme presented a penetration power value into an egg phosphatidylcholine monomolecular film that was comparable to that of HPL and lower than that of TPL. Chymotrypsin, trypsin, and thermolysin were able to hydrolyze OPL and TPL in different ways. In both cases, only N-terminal fragments accumulated during the hydrolysis, whereas no C-terminal fragment was obtained in either case. Tryptic cleavage of OPL and TPL completely degraded the enzymes. Nevertheless, chymotryptic attack generated 35-kd and 43-kd forms for TPL and OPL, respectively. Interestingly, the OPL 43-kd form was inactive, whereas the TPL 35-kd protein conserved its lipolytic activity.

CONCLUSIONS

OPL, TPL, and mammal pancreatic lipases share a high amino acid sequence homology. Further investigations are, however, needed to identify key residues involved in substrate recognition responsible for biochemical differences between the 2 classes of lipases.

Modulating the activity of avian pancreatic lipases by an alkyl chain reacting with an accessible sulfhydryl group

Both turkey (TPL) and chicken (CPL) pancreatic lipases possess only one exposed sulfhydryl residue (Cystein114). After preincubation with the lipase, the sulfhydryl reagent C12 -TNB was found to be a powerful inhibitor of TPL whereas it had no effect on the CPL activity. Based on the 3D structure modelling and the molecular dynamics, the bulky dodecyl chain might hamper the lid movement of the TPL leading to the lipase inhibition upon reaction with C12 -TNB. Meanwhile, the predicted position of the C12 chain linked to Cystein114 of CPL could not block the lid opening mechanism which explains the absence of inhibition by C12 -TNB. Surprisingly, when added during the substrate hydrolysis, C12 -TNB activated the TPL but not the CPL that was slightly inhibited under these conditions. The 3D structure model generated for the open forms of C12 -TPL and C12 -CPL complexes showed that Cystein114 is still accessible and might react with C12 -TNB. Our models clearly explain the activation of TPL and the partial inhibition of CPL after the binding of the C12 chain to the enzyme.

Crab digestive lipase acting at high temperature: Purification and biochemical characterization

In recent years, recovery and characterization of enzymes from fish and aquatic invertebrates have taken place and this had led to the emergence of some interesting new applications of these enzymes. However, much less is known about lipases from crustaceans. A lipolytic activity was located in the crab digestive glands (hepatopancreas), from which a crab digestive lipase (CDL) was purified. Pure CDL has a molecular mass of 65kDa as determined by SDS/PAGE analysis. Unlike known digestive lipases, CDL displayed its maximal activity on long and short-chain triacylglycerols at a temperature of 60 degrees C. A specific activity of 500U/mg or 130U/mg was obtained with TC(4) or olive oil as substrate, respectively. Only 10% of the maximal activity was detected at 37 degrees C. The enzyme retained 80% of its maximal activity when incubated during 10 min at 60 degrees C, and was completely inactivated at a temperature higher than 65 degrees C. Interestingly, neither colipase, nor bile salts were detected in the crab hepatopancreas. Which suggests that colipase evolved in invertebrates simultaneously with the appearance of an exocrine pancreas and a true liver which produce bile salts. No similarity between the 13 N-terminal amino acid residues of CDL was found with those of known other digestive lipases.