title: Hydrophobic interactions between the secondary structures on the molecular surface reinforce the alkaline stability of serine protease.
abstract: We employed random mutagenesis to determine the region of the initial unfolding of hyper-alkaline-sensitive subtilisin, ALP I, that precedes the denaturation of the entire protein under highly alkaline conditions. This region comprises two alpha-helices and a calcium-binding loop. Stabilization of the region caused the stabilization of the entire protein at a high alkaline pH 12. The alkaline stability of this region was most effectively improved by hydrophobic interactions, followed by ionic interactions with Arg residues. The effect of mutations on the improvement was different with regard to the alkaline stability and thermostability. This indicated that different strategies were necessary to improve the alkaline stability and thermostability of the protein.
authors.affiliation: Laboratory of Molecular Enzymology, Division of Life Science, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Oguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Maeda
authors.forename: Keietsu
authors.initials: K
authors.lastname: Abe
authors.forename: Tasuku
authors.initials: T
authors.lastname: Nakajima
authors.forename: Takafumi
authors.initials: T
authors.lastname: Uchida
authors.forename: Youhei
authors.initials: Y
authors.lastname: Yamagata
mesh_terms: D004795:Enzyme Stability; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D009154:Mutation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012697:Serine Endopeptidases / Q000737:chemistry*
chemical_list: D012697:Serine Endopeptidases