Directed evolution to enhance thermostability of galacto-N-biose/lacto-N-biose I phosphorylase.
Koyama, Y., Hidaka, M., Nishimoto, M., Kitaoka, M.(2013) Protein Eng Des Sel 26: 755-761
- PubMed: 24065834 
- DOI: https://doi.org/10.1093/protein/gzt049
- Primary Citation of Related Structures:  
3WFZ - PubMed Abstract: 
Galacto-N-biose/lacto-N-biose I phosphorylase (GLNBP) is the key enzyme in the enzymatic production of lacto-N-biose I. For the purpose of industrial use, we improved the thermostability of GLNBP by evolutionary engineering in which five substitutions in the amino acid sequence were selected from a random mutagenesis GLNBP library constructed using error-prone polymerase chain reaction. Among them, C236Y and D576V mutants showed considerably improved thermostability. Structural analysis of C236Y revealed that the hydroxyl group of Tyr236 forms a hydrogen bond with the carboxyl group of E319. The C236Y and D576V mutations together contributed to the thermostability. The C236Y/D576V mutant exhibited 20°C higher thermostability than the wild type.
Organizational Affiliation: 
National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.