Fontbonne H.,BiosCiences ISM2 |
Brisson L.,BiosCiences ISM2 |
Verine A.,French Institute of Health and Medical Research |
Puigserver A.,BiosCiences ISM2 |
And 2 more authors.
Journal of Biochemistry | Year: 2011
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 pnpC8, 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. © The Authors 2010.