Interfacial Activation of Candida antarctica Lipase B: Combined Evidence from Experiment and Simulation.
Lipase immobilization is frequently used for altering the catalytic properties of these industrially used enzymes. Many lipases bind strongly to hydrophobic surfaces where they undergo interfacial activation. Candida antarctica lipase B (CalB), one of the most commonly used biocatalysts, is frequently discussed as an atypical lipase lacking interfacial activation. Here we show that CalB displays an enhanced catalytic rate for large, bulky substrates when adsorbed to a hydrophobic interface composed of densely packed alkyl chains. We attribute this increased activity of more than 7-fold to a conformational change that yields a more open active site. This hypothesis is supported by molecular dynamics simulations that show a high mobility for a small "lid" (helix α5) close to the active site. Molecular docking calculations confirm that a highly open conformation of this helix is required for binding large, bulky substrates and that this conformation is favored in a hydrophobic environment. Taken together, our combined approach provides clear evidence for the interfacial activation of CalB on highly hydrophobic surfaces. In contrast to other lipases, however, the conformational change only affects large, bulky substrates, leading to the conclusion that CalB acts like an esterase for small substrates and as a lipase for substrates with large alcohol substituents.
Institute for Molecules and Materials, Radboud University , Department of Molecular Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Themistoklis
T
Zisis
Department of Biological Chemistry, University of Michigan Medical School , Ann Arbor, Michigan 48109, United States.
Lydia
L
Freddolino
Institute for Molecules and Materials, Radboud University , Department of Molecular Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Petri
P
Turunen
Institute for Molecules and Materials, Radboud University , Department of Molecular Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Muriel C F
MC
van Teeseling
Institute for Molecules and Materials, Radboud University , Department of Molecular Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Alan E
AE
Rowan
Institute for Molecules and Materials, Radboud University , Department of Molecular Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Kerstin G
KG
Blank
D000327:Adsorption; D002175:Candida / Q000737:chemistry / Q000201:enzymology*; D020134:Catalytic Domain; D004789:Enzyme Activation; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation
D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D008049:Lipase; C431349:lipase B, Candida antarctica