title: Analysis of the stabilization of hen lysozyme by helix macrodipole and charged side chain interaction.
abstract: In the N-terminal region of the alpha-helix of the c-type lysozymes, two Asx residues exist at the 18th and 27th positions. Hen lysozyme has Asp18/Asn27 (18D/27N), and we prepared three mutant lysozymes, Asn18/Asn27 (18N/27N), Asn18/Asp27 (18N/27D), and Asp18/Asp27 (18D/27D). The stability of the wild-type (18D/27N) lysozyme supported the existence of a hydrogen bond between the side chain of Asp18 and the amide group at the N1 position in the alpha-helix, while the stability of the 18N/27D lysozyme supported the presence of the capping box between the Ser24 (N-cap) and Asp27 residues. Although electrostatic repulsion was observed between Asp18 and Asp27 residues in 18D/27D lysozyme, the dissociation of each residue contributed to stabilizing the B-helix in 18D/27D lysozyme through hydrogen bonding and charge-helix macrodipole interaction. This is the first evidence that two neighboring negative charges at the N-terminus of the helix both increased the stability of the protein.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyushu University 62, Fukuoka.
authors.forename: H
authors.initials: H
authors.lastname: Motoshima
authors.forename: S
authors.initials: S
authors.lastname: Mine
authors.forename: K
authors.initials: K
authors.lastname: Masumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Abe
authors.forename: H
authors.initials: H
authors.lastname: Iwashita
authors.forename: Y
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Y
authors.initials: Y
authors.lastname: Chijiiwa
authors.forename: T
authors.initials: T
authors.lastname: Ueda
authors.forename: T
authors.initials: T
authors.lastname: Imoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004795:Enzyme Stability; D005260:Female; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry*; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
chemical_list: D009113:Muramidase