TY - JOUR
T1 - A comparative kinetic study on human pancreatic and Thermomyces lanuginosa lipases
T2 - Inhibitory effects of tetrahydrolipstatin in the presence of lipid substrates
AU - Tiss, Ali
AU - Lengsfeld, Hans
AU - Verger, Robert
PY - 2010/1/1
Y1 - 2010/1/1
N2 - The inhibitory effects of tetrahydrolipstatin (THL) on the hydrolytic activity of human pancreatic lipase (HPL) and T. lanuginosa lipase (TLL) on various lipidic substrates 'poisoned' with THL as previously described was studied, using either the pH-stat, monomolecular film or oil drop technique. Prior to adding lipase (method C), an ethanolic solution of THL was injected in a tributyrin (TC4) or a purified soybean oil (PSO) emulsion prepared in a pH-stat vessel. Under these conditions, THL was found to be a potent HPL inhibitor. After being dissolved in the pure triglyceride phase (method D), THL also strongly inhibited HPL. However, with TC4 as substrate TLL was efficiently inhibited by THL only when method C was used and not method D. The very different inhibitory effects on HPL and TLL recorded with method D and PSO as substrate were confirmed using the monomolecular film and oil drop techniques. With a monomolecular film of dicaprin (di-C10) as substrate, 1 molecule of THL embedded in 400 000 molecules of di-C10 sufficed to reduce the HPL activity to half of its initial value. HPL was therefore efficiently inhibited by THL with all the methods and substrates tested here. Paradoxically, TLL was inhibited by THL molecules transiently present in the aqueous phase and not by the THL molecules present at the triglyceride/water interface. It should therefore be stressed that the inhibitory effects of THL on each lipase depend strongly on the method and the substrate used.
AB - The inhibitory effects of tetrahydrolipstatin (THL) on the hydrolytic activity of human pancreatic lipase (HPL) and T. lanuginosa lipase (TLL) on various lipidic substrates 'poisoned' with THL as previously described was studied, using either the pH-stat, monomolecular film or oil drop technique. Prior to adding lipase (method C), an ethanolic solution of THL was injected in a tributyrin (TC4) or a purified soybean oil (PSO) emulsion prepared in a pH-stat vessel. Under these conditions, THL was found to be a potent HPL inhibitor. After being dissolved in the pure triglyceride phase (method D), THL also strongly inhibited HPL. However, with TC4 as substrate TLL was efficiently inhibited by THL only when method C was used and not method D. The very different inhibitory effects on HPL and TLL recorded with method D and PSO as substrate were confirmed using the monomolecular film and oil drop techniques. With a monomolecular film of dicaprin (di-C10) as substrate, 1 molecule of THL embedded in 400 000 molecules of di-C10 sufficed to reduce the HPL activity to half of its initial value. HPL was therefore efficiently inhibited by THL with all the methods and substrates tested here. Paradoxically, TLL was inhibited by THL molecules transiently present in the aqueous phase and not by the THL molecules present at the triglyceride/water interface. It should therefore be stressed that the inhibitory effects of THL on each lipase depend strongly on the method and the substrate used.
KW - Inhibition
KW - Lipases
KW - Monomolecular film
KW - Oil drop
KW - Orlistat
KW - pH-stat
KW - Tetrahydrolipstatin
UR - http://www.scopus.com/inward/record.url?scp=71549118849&partnerID=8YFLogxK
U2 - 10.1016/j.molcatb.2009.08.011
DO - 10.1016/j.molcatb.2009.08.011
M3 - Article
AN - SCOPUS:71549118849
VL - 62
SP - 19
EP - 26
JO - Journal of Molecular Catalysis - B Enzymatic
JF - Journal of Molecular Catalysis - B Enzymatic
SN - 1381-1177
IS - 1
ER -