Pure human pancreatic bile-salt-dependent lipase, devoid of its oncofetal glycoform [Mas, E., Abouakil, N., Roudani, S., Miralles, F., Guy-Crotte, O., Figarella, C., Escribano, M. J. & Lombardo, D.(1993) Biochem. J. 289, 609-6151, was analyzed on immobilized concanavalin A (ConA). Two variants were separated : an unabsorbed ConA-unreactive fraction ; and an absorbed ConA-reactive fraction. Carbohydrate compositions of ConA-reactive and ConA-unreactive fractions were not significantly different, and analysis of 'H-labelled oligosaccharides liberated from these fractions on the ConA-Sepharose column indicated that the fractionation of the bile-salt-dependent lipase on this column depends upon oligosaccharide structures. The activity of the ConA-reactive fraction was however much lower, independent of the substrate (4-nitrophenyl hexanoate or cholesteryl esters), than that of the ConA-unreactive fraction. Therefore, catalytic constants for the hydrolysis of 4-nitrophenyl hexanoate were determined; both fractions had quite similar K,,, while the k,,, for the ConA-unreactive fraction was 3-4-fold higher than that of the ConA-reactive fraction. ConA-reactive and ConA-unreactive fractions were shown to have slightly different molecular masses and different amino acid compositions. Cleavage patterns after cyanogen bromide treatment of the ConA-reactive and ConA-unreactive fractions suggested that the ConA-reactive (high M , form) and ConA-unreactive (low M , form) forms could be different isoforms of the bile-saltdependent lipase secreted by the human pancreas.Keywords: bile-salt-dependent lipase; human pancreatic juice ; concanavalin A ; feto-acinar pancreatic protein; glycoform.Bile-salt-dependent lipase (BSDL ; also referred to as carboxylic ester hydrolase or carboxyl ester lipase) catalyzes the hydrolysis of lipid-ester substrates and is the only enzyme of the pancreatic juice capable of hydrolyzing fat-soluble vitamin esters (reviewed in [l-31). This enzyme is found in all examined species [l-41. Moreover the enzyme is also present in milk of some primates (51 and carnivore [6]. The enzyme is a prerequisite for full absorption of cholesterol and vitamins. Because of this important physiological role, studies of factors regulating the activity of BSDL are of great interest. Whatever their origin, BSDL are glycosylated and have an N-glycosylation site at As11187 [7], which is close to Ser194, which is involved in the active site [8]. Previous data indicated that the transfer en bloc of the oligosaccharide precursor to the nascent BSDL is essential for the correct folding of the enzyme and is required for its secretion [9]. In contrast, based on results obtained by site-di- is unclear [12]. In BSDL, 0-linked structures hypothetically mask PEST sequences [13] present on the tandemly repeated sequences [14]. These PEST sequences participate in targeting cell proteins into a degradative pathway [14].We have previously isolated an oncofetal glycoform of BSDL [I 51, further identified as the feto-acinar pancreatic protein...