P. Canioni

Bio: P. Canioni is an academic researcher from University of Provence. The author has contributed to research in topics: Colipase & Lipase. The author has an hindex of 11, co-authored 13 publications receiving 488 citations.

Studies on the Effect of Bile Salt and Colipase on Enzymatic Lipolysis. Improved Method for the Determination of Pancreatic Lipase and Colipase

Abstract: The rate of hydrolysis of long chain triglycerides by pure bovine pancreatic lipase has been determined in the presence of variable amounts of bile salts and colipase. Cofactor-free lipase is strongly inhibited by sodium taurodesoxycholate and by mixed bovine bile salts at concentrations higher than the critical micellar concentration. Bile salt inhibited lipase is reactivated by the addition of bovine colipase. Gel filtration of pancreatic juice from several species (Cow, dog, pig) on Sephadex G 100 allows the separation of lipase from colipase. It is found that the enzyme catalyzed hydrolysis of long chain triglycerides by pancreatic lipase from one species is activated by the addition of colipase from other species. Studies on the activation of pancreatic lipase by colipase in the presence of bile salts allowed the re-evaluation of optimal conditions for the determination of lipase and the development of a procedure to assay colipase.

Influence of the pH of cardioplegic solutions on intracellular pH, high-energy phosphates, and postarrest performance. Protective effects of acidotic, glutamate-containing cardioplegic perfusates.

Abstract: The common practice of using alkalotic cardioplegic solutions is not supported by experimental evidence. The present study was conducted (1) to assess the effects of varying the pH (7.00,7.40, and 7.70 at 20° C) of a glutamate-containing cardioplegic solution on intracellular pH, high-energy phosphate content, and postarrest functional recovery and (2) to compare the effects of various buffers (glutamate, bicarbonate, TRIS, and histidine) at a given pH (7.00 and 7.40). Isolated perfused rat hearts were subjected to 2 hours of cardioplegic arrest at 15° C followed by 30 minutes of reperfusion. Intracellular pH and high-energy phosphate content were measured at 4 minute intervals by phosphorus 31 nuclear magnetic resonance spectroscopy. These data were correlated with postischemic recovery of function. There was no significant difference between the intracellular pH values recorded at the end of arrest in the three glutamate-containing groups. However, the acidotic solution (pH 7.00) resulted in better preservation than the alkalotic solution (pH 7.70), as evidenced by (1) a higher creatine phosphate content at the end of arrest (61% ± 9% of control values versus 30% ± 9% [mean ± standard error of the mean], p

Characterization of Triton X 100 extracted colipase from porcine pancreas.

Abstract: Summary Colipase was isolated from porcine pancreas homogenate prepared in the presence of detergent (Triton X 100). After precipitation by ammonium sulfate and ethanol, the cofactor was purified by chromatography on SP-Sephadex in the presence of Triton X 100 and on DEAE-cellulose in the absence of detergent. Two molecular forms of porcine colipase were obtained. They represent 80 per cent (colipase A) and 20 per cent (colipase B), respectively, of the total colipase. Valine is the N-terminal residue of both proteins. Their aminoacid composition is similar to that found by Borgstrom for the two forms of porcine colipase. Determination of the sequence of the first sixteen residues at the N-terminal end of colipase A indicates that the cofactor undergoes no proteolytic degradation in this region of the molecule when extraction is carried out in the presence of detergent. The recovery of colipase is about 30 per cent.

Ovine pancreatic lipase : purification and some properties.

Abstract: Summary Lipase has been isolated from sheep pancreas. The lipoprotein complex formed in pancreas homogenates by the enzyme and endogenous lipids is split by treatment with acetone. Lipase is further purified by ion-exchange chromatography and gel filtration. The molecular weight and the amino-acid composition of ovine lipase are very similar to that of the porcine and bovine enzymes. As previously found in bovine lipase, no carbohydrate is covalently bound to the polypeptide chain which has a N-terminal residue of lysine. The study of the catalytic properties of ovine pancreatic lipase indicates that the enzyme is fully activated by colipase from various species in the presence of conjugated bile salt micellar solutions.

Lipases at interfaces : a review

Abstract: Lipases are acyl hydrolases that play a key role in fat digestion by cleaving long-chain triglycerides into polar lipids Due to an opposite polarity between the enzyme (hydrophilic) and their substrates (lipophilic), lipase reaction occurs at the interface between the aqueous and the oil phases Hence, interfaces are the key spots for lipase biocatalysis and an appropriate site for modulating lipolysis Surprisingly enough, knowledge about the effects of the interfacial composition on lipase catalysis is still limited and only described by the term "interfacial quality" Recent systematic studies based on a biophysical approach allowed for the first time to show the effects of the interfacial microenvironment on lipase catalysis These studies demonstrate that lipase activity as a function of interfacial composition is more attributed to substrate inaccessibility rather than to enzyme denaturation or inactivation, as it is often hypothesized A detailed analysis of the interfacial properties of all compounds involved in triglyceride digestion revealed that lipolysis is a self-regulated reaction This feedback mechanism can be explored as a new avenue to control lipase catalysis To substantiate this hypothesis, oil hydrolysis in a model gastro-intestinal system was performed, which can be seen as an interfacial engineering approach to enzyme reactivity control The presented characterization of the interfacial composition and its consequences provide a new approach for the understanding of lipase reactions at interfaces with direct impact on biotechnological and health care applications

Kinetics and mechanisms of reactions catalysed by immobilized lipases.

Abstract: This review focuses on the kinetics and mechanisms of reactions catalysed by immobilized lipases. The effects of pH, temperature, and various substances on the catalytic properties of immobilized lipases and on the processes by which they are deactivated are reviewed and discussed.

Studies on the detergent inhibition of pancreatic lipase activity.

Abstract: Pancreatic lipase requires colipase, a protein cofactor, to counteract the in vitro inhibition by bile salt. Lipase activity is inhibited by nonsteroidic detergents regardless of their charge and structure. Detergent-inhibited lipase is reactivated by colipase but in all cases activation is limited to a narrow range of detergent concentration. Complementary studies on the bile salt and detergent effect on lipase activity and on interfacial tension at the substrate-water interface show that inhibition is not related to the interfacial surface tension. It is hypothesized that absorption of amphiphilic compounds to the substrate surface modifies the distribution of the enzyme between the lipid surface and the aqueous phase. The activity of detergent-inhibited lipase is fully restored by adding bile salt to the reaction system. Bile salt might play a critical role during in vivo lipolysis by desorbing surface-active substances from the lipid-water interface thus allowing lipase and colipase to interact with substrate.

New Na(+)-H+ exchange inhibitor HOE 694 improves postischemic function and high-energy phosphate resynthesis and reduces Ca2+ overload in isolated perfused rabbit heart.

Abstract: BACKGROUND Experiments were carried out using the new Na(+)-H+ exchange inhibitor (3-methylsulfonyl-4-piperidinobenzoyl)guanidine methanesulfonate (HOE 694) to assess the role of Na(+)-H+ exchange in myocardial ischemic and reperfusion injury. METHODS AND RESULTS Three groups of rabbit hearts (n = 5 in each) were perfused with blood and were subjected to 45 minutes of global normothermic (37 degrees C) ischemia, followed by 1 hour of reperfusion. Group 1 was the control group (vehicle only); in group 2, HOE 694 (1 mumol/L) was administered before ischemia (pretreatment group); and in group 3, HOE 694 was given only during reperfusion to separate actions exerted during ischemia from those specifically obtained during reperfusion. End-diastolic pressure rise at 1 hour of reperfusion was reduced by administration of HOE 694 starting before ischemia (from 52.2 +/- 8.5 mm Hg in group 1 to 17.6 +/- 4.5 mm Hg in group 2, P CONCLUSIONS Postischemic dysfunction was associated with a rise in end-diastolic pressure. This rise was effectively blocked by HOE 694. The drug was most effective when hearts were treated before ischemia, although partial protection was observed when administration was started on reperfusion. The action of HOE 694 strengthens the idea that Na(+)-H+ exchange during both ischemia and reperfusion contributes to contractile dysfunction.