Aldehyde dehydrogenase. Maintaining critical active site geometry at motif 8 in the class 3 enzyme.
Alignment of all known, diverse members of the aldehyde dehydrogenase (ALDH) extended family revealed only two strictly conserved, nonglycine residues, a glutamate and a phenylalanine residue. Both occur in one of the highly conserved 'motif' segments and both occupy strategic locations in the tertiary structure at the bottom of the catalytic funnel. In class 3 ALDH, these are Glu333 and Phe335. In addition, Asp247, which is not highly conserved but is characteristic of class 3 ALDHs, hydrogen bonds the main chain between Glu333 and Phe335. These three residues were mutated conservatively. Michaelis constants determined for both NAD/propanal and NADP/benzaldehyde substrate pairs show all three residues to be crucial to effective catalysis, and suggest that the hydrogen bond to Asp247 is a key element in maintaining precise geometry of key elements at the active site.
Hempel
J
J
Department of Biological Sciences, University of Pittsburgh, Pittsburgh 15620, USA. hempel@psc.edu
Kuo
I
I
Perozich
J
J
Wang
B C
BC
Lindahl
R
R
Nicholas
H
H
D000444:Aldehyde Dehydrogenase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D020816:Amino Acid Motifs; D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry; D001665:Binding Sites; D002384:Catalysis; D018076:DNA, Complementary / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry; D006801:Humans; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010649:Phenylalanine / Q000737:chemistry; D051381:Rats
D018076:DNA, Complementary; D001224:Aspartic Acid; D018698:Glutamic Acid; D010649:Phenylalanine; D000444:Aldehyde Dehydrogenase