Suppression of Water as a Nucleophile in Candida antarctica Lipase B Catalysis

• Published in: ChemBioChem
• Main Authors: Larsen, Marianne Wittrup, Zielinska, Dorota F., Martinelle, Mats, Hidalgo, Aurelio, Jensen, Lars Juhl, Bornscheuer, Uwe T., Hult, Karl
• Other Authors: Swedish Research Council, Swedish Foundation for International Cooperation in Research and Higher Education, Swedish Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-VCH 2010
• Subjects: Candida antarctica; Lipase B; Hydrolysis; Library screening; Mutagenesis; Rational design; Transacylation; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/10261/74747; https://doi.org/10.1002/cbic.200900743; https://doi.org/10.13039/501100001728; https://doi.org/10.13039/100013443

A water tunnel in Candida antarctica lipase B that provides the active site with substrate water is hypothesized. A small, focused library created in order to prevent water from entering the active site through the tunnel was screened for increased transacylation over hydrolysis activity. A single mutant, S47L, in which the inner part of the tunnel was blocked, catalysed the transacylation of vinyl butyrate to 20 mm butanol 14 times faster than hydrolysis. The single mutant Q46A, which has a more open outer end of the tunnel, showed an increased hydrolysis rate and a decreased hydrolysis to transacylation ratio compared to the wild-type lipase. Mutants with a blocked tunnel could be very useful in applications in which hydrolysis is unwanted, such as the acylation of highly hydrophilic compounds in the presence of water. Financial support from the Swedish Research Council, The Swedish Foundation for International Cooperation in Research and Higher Educations and The Swedish Institute. Peer reviewed