Analysis of the stabilization of hen lysozyme by helix macrodipole and charged side chain interaction.
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.
Motoshima
H
H
Graduate School of Pharmaceutical Sciences, Kyushu University 62, Fukuoka.
Mine
S
S
Masumoto
K
K
Abe
Y
Y
Iwashita
H
H
Hashimoto
Y
Y
Chijiiwa
Y
Y
Ueda
T
T
Imoto
T
T
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
D009113:Muramidase