Increase of the protease activity of aqualysin I, a thermostable serine protease, by replacing Asn219 near the catalytic residue Ser222.
Functional role of Asn219 of aqualysin I, a thermostable serine protease from Thermus aquaticus, was investigated by using site-directed mutagenesis. Replacement of Asn219 with serine increased the catalytic efficiency (kcat/Km) for synthetic peptide substrates about twice as much as that of the wild type, while threonine replacement caused a slight decrease in the efficiency. Such replacements resulted in a significant change of kcat rather than Km, indicating that the side chain in the vicinity of the catalytic residue Ser222 affects the catalytic rate constant.
Lin
S J
SJ
Department of Biotechnology, University of Tokyo, Japan.
Kim
D W
DW
Ryugo
Y
Y
Wakagi
T
T
Matsuzawa
H
H
D001216:Asparagine / Q000737:chemistry*; D002384:Catalysis; D004795:Enzyme Stability; D006868:Hydrolysis; D007700:Kinetics; D012694:Serine / Q000737:chemistry*; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D013824:Thermus / Q000201:enzymology
D012694:Serine; D001216:Asparagine; D012697:Serine Endopeptidases; C055102:aqualysin I