Human gastric lipase: a sulfhydryl enzyme.
One sulfhydryl group was modified per mol of native human gastric lipase after incubation at pH 8.0 with 5,5'-dithiobis(2-nitrobenzoic acid) for 18 h or with 4,4'-dithiopyridine for 100 min. With both reagents a direct correlation was found between the modification of one sulfhydryl group and the loss of human gastric lipase activity. Incubation of human gastric lipase with a new hydrophobic sulfhydryl reagent dodecyldithio-5-(2-nitrobenzoic acid) in 30-fold molar excess, at pH 3.0, 5.0, and 8.0, induced immediate and complete human gastric lipase inactivation. Unlike 5,5'-dithiobis(2-nitrobenzoic acid) and 4,4'-dithiopyridine, dodecyldithio-5-(2-nitrobenzoic acid) almost instantaneously stopped the course of tributyrin hydrolysis by human gastric lipase. Human gastric lipase can thus be said to be a sulfhydryl enzyme.
Gargouri
Y
Y
Centre de Biochimie et de Biologie Moléculaire, Centre National de la Recherche Scientifique, Marseille, France.
Moreau
H
H
Pieroni
G
G
Verger
R
R
D000465:Algorithms; D004220:Disulfides; D004228:Dithionitrobenzoic Acid; D005750:Gastric Juice / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000032:analysis*; D008066:Lipolysis; D009579:Nitrobenzoates; D011725:Pyridines; D013438:Sulfhydryl Compounds / Q000032:analysis*
D004220:Disulfides; D009579:Nitrobenzoates; D011725:Pyridines; D013438:Sulfhydryl Compounds; C054898:dodecyldithio-5-(2-nitrobenzoic acid); C011136:thionitrobenzoic acid; C007542:4,4'-dipyridyl disulfide; D004228:Dithionitrobenzoic Acid; D008049:Lipase