Mutant strains of Acinetobacter calcoaceticus possessing additional mandelate dehydrogenases. Identification and preliminary characterization of the enzymes.
Acinetobacter calcoaceticus wild-type strain N.C.I.B. 8250 can grow on only the L(+)-isomer of mandelate but mutant strains have been isolated that can grow on D(-)-mandelate. These mutants contain a novel D(-)-mandelate dehydrogenase in addition to the original L(+)-mandelate dehydrogenase. A second wild-type strain, EBF 65/65, shows the opposite pattern and can grow on D(-)-mandelate but not on L(+)-mandelate; mutants have been isolated that possess an L(+)-mandelate dehydrogenase in addition to the original D(-)-mandelate dehydrogenase and can thus grow on L(+)-mandelate. Both L(+)- and D(-)-mandelate dehydrogenases, whether originally present or evolved, are very similar in many respects: they are membrane-bound and NAD(P)+-independent; their activities have similar dependence on temperature and pH; they are inhibited by oxalate but not by several metal-chelating agents; they are stereospecific in their action and are inhibited by the opposite stereoisomers. D(-)-Mandelate dehydrogenase is much more susceptible than L(+)-mandelate dehydrogenase to inhibition by HgCl2 and p-chloromercuribenzoate and is much more heat-labile.
D000150:Acinetobacter / Q000201:enzymology* / Q000254:growth & development; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D007700:Kinetics; D008333:Mandelic Acids / Q000378:metabolism; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D013237:Stereoisomerism
D008333:Mandelic Acids; D000429:Alcohol Oxidoreductases; C021538:L-mandelate dehydrogenase; C037938:mandelic acid; D010100:Oxygen