A catalytic role for threonine-12 of E. coli asparaginase II as established by site-directed mutagenesis.
A threonine-12 to alanine mutant of E. coli asparaginase II (EC 3.5.1.1) has less than 0.01% of the activity of wild-type enzyme. Both tertiary and quaternary structure of the enzyme are essentially unaffected by the mutation; thus the activity loss seems to be the result of a direct impairment of catalytic function. As aspartate is still bound by the mutant enzyme, Thr-12 appears not be involved in substrate binding.
Harms
E
E
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
Wehner
A
A
Aung
H P
HP
Röhm
K H
KH
D001215:Asparaginase / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002384:Catalysis; D004926:Escherichia coli / Q000201:enzymology*; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013912:Threonine / Q000378:metabolism*
D046911:Macromolecular Substances; D013912:Threonine; D001215:Asparaginase