Pancreatic phospholipase A2 hydrolysis of phosphatidylcholines in various physicochemical states
| Autor: | Jacques C. Hauton, Christiane Chabert, Denis Lairon, Robert Verger, Gilles Nalbone, Vigne Jl, Jeannie Leonardi, Monique Charbonnier-Augeire |
|---|---|
| Rok vydání: | 1980 |
| Předmět: |
Swine
Biophysics digestive system Biochemistry Micelle Phospholipases A Bile Acids and Salts Hydrolysis chemistry.chemical_compound Endocrinology Phosphatidylcholine Animals Bile Lipolysis Pancreas Micelles chemistry.chemical_classification Chromatography biology Substrate (chemistry) Egg Yolk Enzyme assay Rats Phospholipases A2 Apolipoproteins Enzyme chemistry Phospholipases Emulsion Phosphatidylcholines biology.protein Emulsions Female Chickens |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism. 620:612-625 |
| ISSN: | 0005-2760 |
| DOI: | 10.1016/0005-2760(80)90153-8 |
| Popis: | Bile salts-phosphatidylcholines-cholesterol mixed micelles, native bile, egg yolk and intralipid emulsions were used as pancreatic phospholipase A2 (EC 3.1.1.4) substrates. The enzyme activity depends on the bile salt/phosphatidylcholine molar ratio. The enzyme had a low specific activity on bile phosphatidylcholines, because of the existence in native bile of a high bile salt/phosphatidylcholine molar ratio generating unfavorable conditions of hydrolysis, as demonstrated with mixed micelles. However when the bile salt/phosphatidylcholine molar ratio from bile was decreased to 2: 1, enzyme activity increases up to an optimum. This optimal activity was about one third that observed when the substrate was mixed micelles. Under these optimal conditions a simultaneous hydrolysis of intralipid and bile phosphatidylcholines mixture shows comparable initial hydrolysis rates. During an extended incubation, however, nearly all intralipid phosphatidyl-cholines and only half the bile phosphatidylcholines were hydrolyzed by pancreatic phospholipase A2. Bile salts mixture or native bile desorb a portion of the phosphatidylcholines from the intralipid emulsion in optimally hydrolysable bile salts phosphatidylcholines mixed micelles. These micelles bind about 85% of the enzyme indicating that hydrolysis occurs primarily in the micellar phase. These results are discussed in terms of fat lipolysis in vivo. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|