Lamb pregastric lipase catalysed hydrolysis of 1,2,3-tri[(cis)-9-octadecenoyl]glycerol: temperature, pH and solvent isotope effects

✍ Scribed by Charmian J. O'Connor; Andrew D. MacKenzie; Richard H. Barton; Paul A.G. Butler

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 921 KB
• Volume: 96
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/1381-1169(94)00035-2

✦ Synopsis

Lamb pregastric lipase, extracted from the tongue and epiglottal region of lamb, has been partially purified and used to catalyse the hydrolysis of (9-10 3H) ( 1,2,3-tris-[ (cis)-9-octadecenoyllglycerol) over the pH range 5.50-7.50 and temperature range 20.0-4O.O"C. Michaelis-Menten plots were constructed for each reaction condition, and allowed evaluation of K,,, and %a* The values of &,, have been fitted to a three-dimensional activity profile. The optimum pH for reactivity was 6.3 f. 0.3 and the optimum temperature 32 * 3°C. Under optimum conditions the values of kcBt and K,,, were 0.073 pm01 . min -' * mg -' and 9 mM, respectively. The reaction has also been studied in DzO as solvent at pD = 6.50 and T= 3O.O"C. The kinetic isotope effects were 1.46 and 1.3 1 for the rate determining acylation and deacylation steps, respectively. The activity of the enzyme was inhibited by the presence of the bile salt, sodium taurocholate.