title: Human bile salt-dependent lipase efficiency on medium-chain acyl-containing substrates: control by sodium taurocholate.
abstract: Bile salt-dependent lipase was purified to homogeneity from lyophilized human milk and used to screen the influence of the acyl chain length (2-16 carbon atoms) on the kinetic constants k(cat) and K(m) of the hydrolysis of para-nitrophenyl (pnp) ester substrates in the presence or absence of sodium taurocholate (NaTC: 0.02-20 mM). The highest k(cat) value (∼3,500 s(-1)) was obtained with pnpC(8) as substrate, whereas the lowest K(m) (<10 µM) was that recorded with pnpC(10). In the absence of NaTC, the maximal catalytic efficiency (k(cat)/K(m)) was obtained with pnpC(8), while in the presence of NaTC k(cat)/K(m) was maximal with pnpC(8), pnpC(10) or pnpC(12). The bile salt activated the enzyme in two successive saturation phases occurring at a micromolar and a millimolar concentration range, respectively. The present data emphasize the suitability of this enzyme for the hydrolysis of medium-chain acyl-containing substrates and throw additional light on how BSDL is activated by NaTC.
authors.affiliation: BiosCiences-ISM2, UMR 6263, CNRS-Université Paul Cézanne-Aix Marseille III, Case 342, Faculté des Sciences et Techniques de Saint Jérôme, Marseille, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Fontbonne
authors.forename: Lydie
authors.initials: L
authors.lastname: Brisson
authors.forename: Alain
authors.initials: A
authors.lastname: Vérine
authors.forename: Antoine
authors.initials: A
authors.lastname: Puigserver
authors.forename: Dominique
authors.initials: D
authors.lastname: Lombardo
authors.forename: El Hassan
authors.initials: el H
authors.lastname: Ajandouz
mesh_terms: D001647:Bile Acids and Salts / Q000378:metabolism; D002384:Catalysis; D004789:Enzyme Activation; D004952:Esters / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008823:Micelles; D008895:Milk, Human / Q000201:enzymology; D009596:Nitrophenols / Q000737:chemistry; D002787:Sterol Esterase / Q000378:metabolism*; D013379:Substrate Specificity; D013656:Taurocholic Acid / Q000378:metabolism*
chemical_list: D001647:Bile Acids and Salts; D004952:Esters; D008823:Micelles; D009596:Nitrophenols; C024719:4-nitrophenyl; D013656:Taurocholic Acid; C054784:bile salt-stimulated lipase; D002787:Sterol Esterase