Determination of (S)- and (R)-2-oxo-3-methylvaleric acid in plasma of patients with maple syrup urine disease.
An enzymatic method for the separate measurement of both chiral 2-oxo-3-methylvaleric acid (OMV) compounds, (S)- and (R)-OMV, by NADH-dependent enantioselective amination using leucine dehydrogenase in the presence of a NADH regenerating system is described. This method allows the quantitative determination of all branched-chain 2-oxo acids, simultaneously. In plasma samples from classical maple syrup urine disease patients under therapy the average (R)-OMV/(S)-OMV ratio was 0.35 and great differences in the transamination equilibria of the diastereomeric branched-chain amino acids L-isoleucine and L-alloisoleucine were demonstrated.
Wendel
U
U
Kinderklinik, Heinrich-Heine-Universität, Düsseldorf, FRG.
Even
G
G
Langenbeck
U
U
Schadewaldt
P
P
Hummel
W
W
D000594:Amino Acid Oxidoreductases; D006801:Humans; D007651:Keto Acids / Q000097:blood* / Q000737:chemistry; D050803:Leucine Dehydrogenase; D008375:Maple Syrup Urine Disease / Q000097:blood*; D009243:NAD
D007651:Keto Acids; D009243:NAD; C016211:alpha-keto-beta-methylvaleric acid; D000594:Amino Acid Oxidoreductases; D050803:Leucine Dehydrogenase