title: Substrate-binding and catalytic roles of Lys194 in the C-terminus in human adenylate kinase by site-directed random mutagenesis.
abstract: Site-directed random mutagenesis of Lys194 residue in the C-terminus of human adenylate kinase (AK) was performed, and six mutants were analyzed by steady-state kinetics. K194-mutants variously affected the apparent Michaelis constants (K(m) values) for ATP and AMP, although the kcat values strikingly decreased. The Lys194 residue appears to interact not only with MgATP2- but also with the AMP2- substrates by salt bridge formation with a nucleotide and to play a functional role in stabilizing the phosphate-transfer during catalysis. Lys194 could be essential for substrate-holdings and in catalysis and not replaceable to the other amino acids.
authors.affiliation: Department of Hygiene, Miyazaki Medical College, Japan. tayabe@post.miyazaki-med.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Ayabe
authors.forename: H
authors.initials: H
authors.lastname: Takenaka
authors.forename: O
authors.initials: O
authors.lastname: Takenaka
authors.forename: T
authors.initials: T
authors.lastname: Onitsuka
authors.forename: K
authors.initials: K
authors.lastname: Shibata
authors.forename: S
authors.initials: S
authors.lastname: Uesugi
authors.forename: M
authors.initials: M
authors.lastname: Hamada
mesh_terms: D000263:Adenylate Kinase / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence / Q000502:physiology; D001483:Base Sequence; D001665:Binding Sites; D006801:Humans; D007700:Kinetics; D008239:Lysine / Q000737:chemistry; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed
chemical_list: D000263:Adenylate Kinase; D008239:Lysine