Drugs online research references
Eur J Biochem. 1992 Apr 1;205(1):383-90.
Large spectral changes accompany the conformational transition of human pancreatic lipase induced by acylation with the inhibitor tetrahydrolipstatin.
Luthi-Peng Q, Winkler FK.
Pharma Division, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
Human pancreatic lipase (HPL) loses more than 80% of its activity when incubated with tetrahydrolipstatin in a buffer containing bile salts. During the inactivation process, large changes are observed in intrinsic tryptophan fluorescence and in the near-ultraviolet circular dichroism. The rate of chemical inactivation is highly comparable to that determined from the time dependence of the spectral changes. It is concluded that HPL undergoes a conformational transition upon inhibitor binding, resulting in a change in the microenvironment of tryptophan residues. Bile salts are needed in this system for effective inactivation of the enzyme by tetrahydrolipstatin, and a large increase in the inactivation rate takes place at about the critical micellar concentration (CMC) of bile salts. The inhibited enzyme can be reactivated by reducing the bile salt concentration to below the CMC, and the changes in tryptophan fluorescence induced by acylation with tetrahydrolipstatin are thereby reversed. This suggests that bile salts above their CMC stabilize the acyl-enzyme complex.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1555598&dopt=Abstract
word match xenical online literature
Eur J Biochem. 1991 Dec 5;202(2):395-400.
Inactivation of pancreatic and gastric lipases by tetrahydrolipstatin and alkyl-dithio-5-(2-nitrobenzoic acid). A kinetic study with 1,2-didecanoyl-sn-glycerol monolayers.
Ransac S, Gargouri Y, Moreau H, Verger R.
Centre de Biochimie et de Biologie Moleculaire, Centre National de Recherche Scientifique, Marseille, France.
We studied the covalent inhibition of lipases by the monolayer technique. We report the inactivation of porcine pancreatic and human and rabbit gastric lipases, acting on mixed monomolecular films of dicaprin containing tetrahydrolipstatin or new hydrophobic disulfide compounds, which can be described as a 'poisoned-interface' system. A kinetic model is presented for depicting the covalent inactivation of lipolytic enzymes at a lipid/water interface. The stoichiometry of the interfacial situation can be described as follows: one lipase molecule embedded among 10(5) substrate molecules will be inactivated to half its initial velocity by the presence of 10 tetrahydrolipstatin molecules. This inactivation was independent of the surface pressure. When tested in the form of mixed films, all the disulfide compounds investigated specifically reduced the hydrolysis of 1,2-didecanoyl-sn-glycerol films by gastric lipases, but did not affect hydrolysis by pancreatic lipase. With this poisoned-interface system, tetrahydrolipstatin was found to be the most potent inactivator, whereas disulfide compounds showed a higher degree of selectivity than tetrahydrolipstatin.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1761041&dopt=Abstract
word match xenical online literature
FEBS Lett. 1991 Jul 29;286(1-2):186-8.
Effects of the lipase inhibitors, Triton WR-1339 and tetrahydrolipstatin, on the synthesis and secretion of lipids by rat hepatocytes.
Hermier D, Hales P, Brindley DN.
Department of Biochemistry, Faculty of Medicine, University of Alberta, Edmonton, Canada.
The lipase inhibitors, Triton WR-1339 and tetrahydrolipstatin, were incubated with rat hepatocytes. Triton WR-1339 increased the recovery of triacylglycerol in the hepatocytes and incubation medium by 31% and 38%, respectively. Tetrahydrolipstatin decreased the accumulation of newly synthesized, and of total triacylglycerol in the medium. This compound might be useful in determining mechanisms involved in intracellular triacylglycerol metabolism and the secretion of very low density lipoproteins.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1864367&dopt=Abstract
word match xenical online literature
Herbs and Pharmaceuticals Online ||
Hair Million herbal formula for hair loss and hair growth ||
Antibiotics and prescription medications online literature ||