Effect on catalysis by replacement of catalytic residue from hen egg white lysozyme to Venerupis philippinarum lysozyme*

Yoshito Abe, Mitsuru Kubota, Shinya Takazaki, Yuji Ito, Hiromi Yamamoto, Dongchon Kang, Tadashi Ueda, Taiji Imoto

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Asn46Asp/Asp52Ser or Asn46Glu/Asp52Ser hen egg white lysozyme (HEL) mutant was designed by introducing the substituted catalytic residue Asp46 or Glu46, respectively, based on Venerupis philippinarum (Vp) lysozyme structure as a representative of invertebrate-type (i-type) lyzozyme. These mutations restored the bell-shaped pH-dependency of the enzyme activity from the sigmoidal pH-dependency observed for the Asp52Ser mutant. Furthermore both lysozyme mutants possessed retaining mechanisms like Vp lysozyme and HEL. The Asn46Glu/Asp52Ser mutant, which has a shorter distance between two catalytic residues, formed a glycosyl adduct in the reaction with the N-acetylglucosamine oligomer. Furthermore, we found the accelerated turnover through its glycosyl adduct formation and decomposition. The turnover rate estimated from the glycosyl formation and decomposition rates was only 20% of the observed hydrolysis rate of the substrate. Based on these results, we discussed the catalytic mechanism of lysozymes.

Original languageEnglish
Pages (from-to)1637-1647
Number of pages11
JournalProtein Science
DOIs
Publication statusPublished - Sep 1 2016

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology

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