Alteration in relative activities of phenylalanine dehydrogenase towards different substrates by site-directed mutagenesis.
Glycine-124 and leucine-307 of phenylalanine dehydrogenase from Bacillus sphaericus were altered by site-specific mutagenesis to the corresponding residues in leucine dehydrogenase: alanine and valine, respectively. These two residues have previously been implicated from molecular modelling as important in determining the substrate discrimination of the two enzymes. Single and double mutants displayed lower activities towards L-phenylalanine and enhanced activity towards almost all aliphatic amino acid substrates tested compared to the wild-type, thus confirming the predictions made from molecular modelling.
Seah
S Y
SY
Department of Biochemistry, University College Dublin, Belfield, Ireland.
Britton
K L
KL
Baker
P J
PJ
Rice
D W
DW
Asano
Y
Y
Engel
P C
PC
D000594:Amino Acid Oxidoreductases / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology*; D001483:Base Sequence; D005998:Glycine; D007700:Kinetics; D007930:Leucine; D050803:Leucine Dehydrogenase; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D017354:Point Mutation; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
D000596:Amino Acids; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D000594:Amino Acid Oxidoreductases; D050803:Leucine Dehydrogenase; C022342:phenylalanine oxidase; D007930:Leucine; D005998:Glycine